From patchwork Tue Nov 22 17:44:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052592 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ACC39C4321E for ; Tue, 22 Nov 2022 17:44:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234058AbiKVRou (ORCPT ); Tue, 22 Nov 2022 12:44:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232554AbiKVRos (ORCPT ); Tue, 22 Nov 2022 12:44:48 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1EB6365F0; Tue, 22 Nov 2022 09:44:48 -0800 (PST) Message-ID: <20221122173648.153480304@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139086; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=vPQpsKvWnASzU3gSCvd8QTllKFezKGed3DBwTOx2RsY=; b=N1JdlAq02OGh1ZaHD7YrDTYMYpCfJwds7yiy47sSsKrsscCku9ZeyGkFcuMMTvaOkg0mBh 9PIu/EEfwcpUmektmw8eBXUbRIeL8LPKNifLEOwbUcHavwajnrvmDsMNnGbo3IQyUdXZE3 fXSH56BsDR1kv3YQrZAOlJRGNJ8q8jTay1HWJcrtsqOAE21A2bq86Iwokid1/4lew92134 cPNG9iXt8FQIj+hPM3lAHZJwoMAl9wuPm0nhRlWwL8b6x5KNFx2wPUBvAez7rHjN+P+FEL y8gVeqCjwX8cKpL7sKtpszLaLpzT+tBYMn517QbefeK8K20Im7s8sN1ptBT8+g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139086; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=vPQpsKvWnASzU3gSCvd8QTllKFezKGed3DBwTOx2RsY=; b=y93AMtrwboI4mg48ccrd69AeqcjYHNWmCsBPWMVYSOFh86bGLdI5qNWUx/E7AoaUQNIPQI 9P/jYXxtnLlR8WAA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 01/17] Documentation: Remove bogus claim about del_timer_sync() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:45 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org del_timer_sync() does not return the number of times it tried to delete the timer which rearms itself. It's clearly documented: The function returns whether it has deactivated a pending timer or not. This part of the documentation is from 2003 where del_timer_sync() really returned the number of deletion attempts for unknown reasons. This code was rewritten in 2005, but the documentation was not updated. Signed-off-by: Thomas Gleixner --- Documentation/kernel-hacking/locking.rst | 3 +-- Documentation/translations/it_IT/kernel-hacking/locking.rst | 4 +--- 2 files changed, 2 insertions(+), 5 deletions(-) --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -1006,8 +1006,7 @@ Another common problem is deleting timer calling add_timer() at the end of their timer function). Because this is a fairly common case which is prone to races, you should use del_timer_sync() (``include/linux/timer.h``) to -handle this case. It returns the number of times the timer had to be -deleted before we finally stopped it from adding itself back in. +handle this case. Locking Speed ============= --- a/Documentation/translations/it_IT/kernel-hacking/locking.rst +++ b/Documentation/translations/it_IT/kernel-hacking/locking.rst @@ -1027,9 +1027,7 @@ Un altro problema è l'eliminazione dei da soli (chiamando add_timer() alla fine della loro esecuzione). Dato che questo è un problema abbastanza comune con una propensione alle corse critiche, dovreste usare del_timer_sync() -(``include/linux/timer.h``) per gestire questo caso. Questa ritorna il -numero di volte che il temporizzatore è stato interrotto prima che -fosse in grado di fermarlo senza che si riavviasse. +(``include/linux/timer.h``) per gestire questo caso. Velocità della sincronizzazione =============================== From patchwork Tue Nov 22 17:44:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052593 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 736DAC433FE for ; Tue, 22 Nov 2022 17:44:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234028AbiKVRow (ORCPT ); Tue, 22 Nov 2022 12:44:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234043AbiKVRou (ORCPT ); Tue, 22 Nov 2022 12:44:50 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F2C01007; Tue, 22 Nov 2022 09:44:49 -0800 (PST) Message-ID: <20221122173648.212328242@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139087; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=n0dkKkggW4roLGRCIUa+7bvzAL1A7Ub2KzNnTnDcHNY=; b=0E277xHlHwEASCx3tpem2m5uapuFuTSTYnfM9klwx6xpeWU795HytfYokSiV52uLoT6i/x WoTFjZnH9Rou3piv/h894XvgsjW3cngyryu4xlrDyNuz1kN6LByQI5p4fMk6CqjA/rH3yY t+XwqWOhLT71ezEPXZQMEsS3CH67nWIYNUHeL+ZW8Ego9g12/8d80IE2LaM/S6pP8pCmaK sS2UeBCp71f5/haB+2t0Pzdxdy/9jUT21uR6oIRhVW4nxDN+AuF6wuPmkA90Ip+EWMXx9A Z7v5JakUq+AFEkrUajjEy/lYjg0D1499DN3AcobPzJECXu7Z3gForkXUo/6Tgg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139087; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=n0dkKkggW4roLGRCIUa+7bvzAL1A7Ub2KzNnTnDcHNY=; b=6quw5LJrGoR+KpCdyTs0STDZEqAy6nHlTz1fYsKRqcumlbeqFT4GQ+JS56ZQ9en6rtO0cI SjKFN3qDApPcoUDw== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 02/17] ARM: spear: Do not use timer namespace for timer_shutdown() function References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:47 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: "Steven Rostedt (Google)" A new "shutdown" timer state is being added to the generic timer code. One of the functions to change the timer into the state is called "timer_shutdown()". This means that there can not be other functions called "timer_shutdown()" as the timer code owns the "timer_*" name space. Rename timer_shutdown() to spear_timer_shutdown() to avoid this conflict. Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Reviewed-by: Guenter Roeck Acked-by: Arnd Bergmann Acked-by: Viresh Kumar Link: https://lkml.kernel.org/r/20221106212701.822440504@goodmis.org Link: https://lore.kernel.org/all/20221105060155.228348078@goodmis.org/ Link: https://lore.kernel.org/r/20221110064146.810953418@goodmis.org --- arch/arm/mach-spear/time.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/arm/mach-spear/time.c b/arch/arm/mach-spear/time.c index e979e2197f8e..5371c824786d 100644 --- a/arch/arm/mach-spear/time.c +++ b/arch/arm/mach-spear/time.c @@ -90,7 +90,7 @@ static void __init spear_clocksource_init(void) 200, 16, clocksource_mmio_readw_up); } -static inline void timer_shutdown(struct clock_event_device *evt) +static inline void spear_timer_shutdown(struct clock_event_device *evt) { u16 val = readw(gpt_base + CR(CLKEVT)); @@ -101,7 +101,7 @@ static inline void timer_shutdown(struct clock_event_device *evt) static int spear_shutdown(struct clock_event_device *evt) { - timer_shutdown(evt); + spear_timer_shutdown(evt); return 0; } @@ -111,7 +111,7 @@ static int spear_set_oneshot(struct clock_event_device *evt) u16 val; /* stop the timer */ - timer_shutdown(evt); + spear_timer_shutdown(evt); val = readw(gpt_base + CR(CLKEVT)); val |= CTRL_ONE_SHOT; @@ -126,7 +126,7 @@ static int spear_set_periodic(struct clock_event_device *evt) u16 val; /* stop the timer */ - timer_shutdown(evt); + spear_timer_shutdown(evt); period = clk_get_rate(gpt_clk) / HZ; period >>= CTRL_PRESCALER16; From patchwork Tue Nov 22 17:44:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052594 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32187C433FE for ; Tue, 22 Nov 2022 17:44:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234244AbiKVRox (ORCPT ); Tue, 22 Nov 2022 12:44:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234139AbiKVRov (ORCPT ); Tue, 22 Nov 2022 12:44:51 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 097BEB7F0; Tue, 22 Nov 2022 09:44:51 -0800 (PST) Message-ID: <20221122173648.271098903@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139089; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=96srhAwXJ3UQoCsDoL5fPAIasWFtP8WUr4N49zZJa6E=; b=Ivj7VoK3DjKbjCxH8WX9OJIELwzqwuS2Wgv4UlZ0L0KwL1gusL26KNWpU9tmNRZPrhuVoY v5max898Ruz7Ba5PtcM66tP/5gzcLWXKZ0svV/j2/j4ety9XGHwnkwrzvA2yNmgN8KM0VQ XTK3hk0drCVm/CGYREuQ0o4pW/1/c5B5TSW3XM4XHnhWFYMH6suIjY6JS/aSpkHDQ7KxzD o/eLYzYvxFnH8hZMnysoFnbnu9XFS+kYEkZYJVR9FpBfTMdi/zXfDgMEiPSvzqg5eFrGU/ MltO0Jear/3kb6TGUDsK326MJgmhq+dPOHBHu5sSq+djXILdOOOe2+ch1yVZ2w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139089; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=96srhAwXJ3UQoCsDoL5fPAIasWFtP8WUr4N49zZJa6E=; b=xL1y+YsCS0L3GDh3vFTdsVG5WGZECuklzuEWFBJC5RbY2ORi7VBoU3YefFYFnJmgX36euO Y4ODl8LD/mwV79Cg== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 03/17] clocksource/drivers/arm_arch_timer: Do not use timer namespace for timer_shutdown() function References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:49 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: "Steven Rostedt (Google)" A new "shutdown" timer state is being added to the generic timer code. One of the functions to change the timer into the state is called "timer_shutdown()". This means that there can not be other functions called "timer_shutdown()" as the timer code owns the "timer_*" name space. Rename timer_shutdown() to arch_timer_shutdown() to avoid this conflict. Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Reviewed-by: Guenter Roeck Acked-by: Marc Zyngier Link: https://lkml.kernel.org/r/20221106212702.002251651@goodmis.org Link: https://lore.kernel.org/all/20221105060155.409832154@goodmis.org/ Link: https://lore.kernel.org/r/20221110064146.981725531@goodmis.org --- drivers/clocksource/arm_arch_timer.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index a7ff77550e17..9c3420a0d19d 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -687,8 +687,8 @@ static irqreturn_t arch_timer_handler_virt_mem(int irq, void *dev_id) return timer_handler(ARCH_TIMER_MEM_VIRT_ACCESS, evt); } -static __always_inline int timer_shutdown(const int access, - struct clock_event_device *clk) +static __always_inline int arch_timer_shutdown(const int access, + struct clock_event_device *clk) { unsigned long ctrl; @@ -701,22 +701,22 @@ static __always_inline int timer_shutdown(const int access, static int arch_timer_shutdown_virt(struct clock_event_device *clk) { - return timer_shutdown(ARCH_TIMER_VIRT_ACCESS, clk); + return arch_timer_shutdown(ARCH_TIMER_VIRT_ACCESS, clk); } static int arch_timer_shutdown_phys(struct clock_event_device *clk) { - return timer_shutdown(ARCH_TIMER_PHYS_ACCESS, clk); + return arch_timer_shutdown(ARCH_TIMER_PHYS_ACCESS, clk); } static int arch_timer_shutdown_virt_mem(struct clock_event_device *clk) { - return timer_shutdown(ARCH_TIMER_MEM_VIRT_ACCESS, clk); + return arch_timer_shutdown(ARCH_TIMER_MEM_VIRT_ACCESS, clk); } static int arch_timer_shutdown_phys_mem(struct clock_event_device *clk) { - return timer_shutdown(ARCH_TIMER_MEM_PHYS_ACCESS, clk); + return arch_timer_shutdown(ARCH_TIMER_MEM_PHYS_ACCESS, clk); } static __always_inline void set_next_event(const int access, unsigned long evt, From patchwork Tue Nov 22 17:44:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052595 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA701C43219 for ; Tue, 22 Nov 2022 17:45:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233379AbiKVRpU (ORCPT ); Tue, 22 Nov 2022 12:45:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234222AbiKVRox (ORCPT ); Tue, 22 Nov 2022 12:44:53 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8D6E12AB3; Tue, 22 Nov 2022 09:44:52 -0800 (PST) Message-ID: <20221122173648.327359885@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139091; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=XkUTDmMIm9+EPawG5WF0ZN1LAtqzHJ1HnPEjTlQs+bs=; b=J3nBFNezDC8uN3ZPfqF3oC/ue8yBWnVxhPJpQZwVsdQ2eXizU6+3VPt/MbZzOc6AyglOei Zt2AmEuAKZnh0qJU+i76Dk9gZy9uUBjgVTjj1ljz1yXXXz3zmiK8jpPpbqxSXKol8nilUc RSH6odc7PeybggsvcyRcPRN0JN5UuHmav8rLUxNmmbAC05P3YnMjq1QHjgeInyTNObDiFU HTWMqdlFUWiTexdziHVD7ZBXs12k783vBwSLjzzi8UV97oIPa/UNb4wuqG0JoZllfxCYw2 8P9A+qRqONzjNCBjN9iXPuJppa9Ijb73fHez3IidGe9E1eKxDLoZ2syEn1XGkA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139091; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=XkUTDmMIm9+EPawG5WF0ZN1LAtqzHJ1HnPEjTlQs+bs=; b=R5tyYplwRwRkuvw3XPzIEGap+FoJrvNzYiWDwUbKs4+7X2ap4Jezy2iZIH2E2ThT9B+75f VIf/GgaA476Wq0Dw== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 04/17] clocksource/drivers/sp804: Do not use timer namespace for timer_shutdown() function References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:50 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: "Steven Rostedt (Google)" A new "shutdown" timer state is being added to the generic timer code. One of the functions to change the timer into the state is called "timer_shutdown()". This means that there can not be other functions called "timer_shutdown()" as the timer code owns the "timer_*" name space. Rename timer_shutdown() to evt_timer_shutdown() to avoid this conflict. Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Reviewed-by: Guenter Roeck Link: https://lkml.kernel.org/r/20221106212702.182883323@goodmis.org Link: https://lore.kernel.org/all/20221105060155.592778858@goodmis.org/ Link: https://lore.kernel.org/r/20221110064147.158230501@goodmis.org --- drivers/clocksource/timer-sp804.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/clocksource/timer-sp804.c b/drivers/clocksource/timer-sp804.c index e6a87f4af2b5..cd1916c05325 100644 --- a/drivers/clocksource/timer-sp804.c +++ b/drivers/clocksource/timer-sp804.c @@ -155,14 +155,14 @@ static irqreturn_t sp804_timer_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } -static inline void timer_shutdown(struct clock_event_device *evt) +static inline void evt_timer_shutdown(struct clock_event_device *evt) { writel(0, common_clkevt->ctrl); } static int sp804_shutdown(struct clock_event_device *evt) { - timer_shutdown(evt); + evt_timer_shutdown(evt); return 0; } @@ -171,7 +171,7 @@ static int sp804_set_periodic(struct clock_event_device *evt) unsigned long ctrl = TIMER_CTRL_32BIT | TIMER_CTRL_IE | TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE; - timer_shutdown(evt); + evt_timer_shutdown(evt); writel(common_clkevt->reload, common_clkevt->load); writel(ctrl, common_clkevt->ctrl); return 0; From patchwork Tue Nov 22 17:44:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052596 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCB2DC4332F for ; Tue, 22 Nov 2022 17:45:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234360AbiKVRpX (ORCPT ); Tue, 22 Nov 2022 12:45:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232997AbiKVRpN (ORCPT ); Tue, 22 Nov 2022 12:45:13 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34249E0EF; Tue, 22 Nov 2022 09:44:54 -0800 (PST) Message-ID: <20221122173648.384019293@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139092; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=99E9RZXEWCqCiftAfx5LaShrhKLLrEVh8g6WFiMjN9M=; b=IvwX0tn17Ty+HwCK4+K/Zt3s+4M7JbDM+Swr7ybPmCPsyzjRIfbCe+clhvH8fWXo5HOWpG 4Z6y6Fnw+n5rK++i1sp2EBLG1H0cD1uvsoHxlHC6z5KKsxYv9+UuMGsO5R25mv+dok7IjL qm2nlbce88UdXA6Sl/InkMUqWYbuZICEfXcgGiRCgAbF1+nhC92ralwpsJzAepqzYFnjmM wZMMTk7OY7k/4LRqEK2Y497fAbvp5EeWphALkohRUNsR5uzC1S+ebqnsOYrfoaD1UuPCib 4D+EyV5IXoljU2XL/4kYqsAiMunBsUwCyW4V3p64a9oQHAhHUt6hIV15VQT/Ew== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139092; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=99E9RZXEWCqCiftAfx5LaShrhKLLrEVh8g6WFiMjN9M=; b=t7Q0ooo70Zc7EfTnirG4ro0vOMJYrf3HStID72Iu2Ouai7aSrFRIIG33ttEht8YbfXzbX3 jOPGgMXZN7t3uIAw== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 05/17] timers: Get rid of del_singleshot_timer_sync() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:52 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org del_singleshot_timer_sync() used to be an optimization for deleting timers which are not rearmed from the timer callback function. This optimization turned out to be broken and got mapped to del_timer_sync() about 17 years ago. Get rid of the undocumented indirection and use del_timer_sync() directly. No functional change. Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck --- drivers/char/tpm/tpm-dev-common.c | 4 ++-- drivers/staging/wlan-ng/hfa384x_usb.c | 4 ++-- drivers/staging/wlan-ng/prism2usb.c | 6 +++--- include/linux/timer.h | 2 -- kernel/time/timer.c | 2 +- net/sunrpc/xprt.c | 2 +- 6 files changed, 9 insertions(+), 11 deletions(-) --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -155,7 +155,7 @@ ssize_t tpm_common_read(struct file *fil out: if (!priv->response_length) { *off = 0; - del_singleshot_timer_sync(&priv->user_read_timer); + del_timer_sync(&priv->user_read_timer); flush_work(&priv->timeout_work); } mutex_unlock(&priv->buffer_mutex); @@ -262,7 +262,7 @@ ssize_t tpm_common_write(struct file *fi void tpm_common_release(struct file *file, struct file_priv *priv) { flush_work(&priv->async_work); - del_singleshot_timer_sync(&priv->user_read_timer); + del_timer_sync(&priv->user_read_timer); flush_work(&priv->timeout_work); file->private_data = NULL; priv->response_length = 0; --- a/drivers/staging/wlan-ng/hfa384x_usb.c +++ b/drivers/staging/wlan-ng/hfa384x_usb.c @@ -1116,8 +1116,8 @@ static int hfa384x_usbctlx_complete_sync if (ctlx == get_active_ctlx(hw)) { spin_unlock_irqrestore(&hw->ctlxq.lock, flags); - del_singleshot_timer_sync(&hw->reqtimer); - del_singleshot_timer_sync(&hw->resptimer); + del_timer_sync(&hw->reqtimer); + del_timer_sync(&hw->resptimer); hw->req_timer_done = 1; hw->resp_timer_done = 1; usb_kill_urb(&hw->ctlx_urb); --- a/drivers/staging/wlan-ng/prism2usb.c +++ b/drivers/staging/wlan-ng/prism2usb.c @@ -170,9 +170,9 @@ static void prism2sta_disconnect_usb(str */ prism2sta_ifstate(wlandev, P80211ENUM_ifstate_disable); - del_singleshot_timer_sync(&hw->throttle); - del_singleshot_timer_sync(&hw->reqtimer); - del_singleshot_timer_sync(&hw->resptimer); + del_timer_sync(&hw->throttle); + del_timer_sync(&hw->reqtimer); + del_timer_sync(&hw->resptimer); /* Unlink all the URBs. This "removes the wheels" * from the entire CTLX handling mechanism. --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -190,8 +190,6 @@ extern int try_to_del_timer_sync(struct # define del_timer_sync(t) del_timer(t) #endif -#define del_singleshot_timer_sync(t) del_timer_sync(t) - extern void init_timers(void); struct hrtimer; extern enum hrtimer_restart it_real_fn(struct hrtimer *); --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1933,7 +1933,7 @@ signed long __sched schedule_timeout(sig timer_setup_on_stack(&timer.timer, process_timeout, 0); __mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING); schedule(); - del_singleshot_timer_sync(&timer.timer); + del_timer_sync(&timer.timer); /* Remove the timer from the object tracker */ destroy_timer_on_stack(&timer.timer); --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1164,7 +1164,7 @@ xprt_request_enqueue_receive(struct rpc_ spin_unlock(&xprt->queue_lock); /* Turn off autodisconnect */ - del_singleshot_timer_sync(&xprt->timer); + del_timer_sync(&xprt->timer); return 0; } From patchwork Tue Nov 22 17:44:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052597 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C0D8C4332F for ; Tue, 22 Nov 2022 17:45:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234268AbiKVRpa (ORCPT ); Tue, 22 Nov 2022 12:45:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233498AbiKVRpS (ORCPT ); Tue, 22 Nov 2022 12:45:18 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D382B65F0; Tue, 22 Nov 2022 09:44:55 -0800 (PST) Message-ID: <20221122173648.442211558@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=idu06WOJve3djJAPc7BtVv8nMt9NfLYdyVD3CA4QRcI=; b=ZYvUvpFjYwMgT90NqNqJBAbZfVeA9cpTH1StBL/7CEhaN1Eq0Dd2LV2hvVdA6iYh+VHsI8 cpetnVScKynrAMAhftuD15H4UgmFS2eeZsYfUBJkiQy59KnMQmBDDla7WfWPkkqjz3+REB ynTYR1170fjBoPjitNb3xtKOD6uqeQcXWuKV2Cbb/3ekBYOQH9tEBfbF8H48YGtHWrP9ZS aTw+sTG3Xd4vEM8RtxB+VpLpwlIpeu3xCPoRIuidkXwpPqtJ5oCsZK9I5wtY/He7YMMDrY ldAn5GL9cQtjsXDUINMmI9pQWCTsQ+xJv1Bz94gSOeN+XYT9eDeu+XQsTOrXKg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=idu06WOJve3djJAPc7BtVv8nMt9NfLYdyVD3CA4QRcI=; b=Uqc/eiX6vOdogzxNUrmROEQVX+aY9FcykUIR2w245p5xg67epAVFF2IuQAObckDw+Tdtch s+j0sOk47YO1grDA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 06/17] timers: Replace BUG_ON()s References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:53 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The timer code still has a few BUG_ON()s left which are crashing the kernel in situations where it still can recover or simply refuse to take an action. Remove the one in the hotplug callback which checks for the CPU being offline. If that happens then the whole hotplug machinery will explode in colourful ways. Replace the rest with WARN_ON_ONCE() and conditional returns where appropriate. Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck --- kernel/time/timer.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1193,7 +1193,8 @@ EXPORT_SYMBOL(timer_reduce); */ void add_timer(struct timer_list *timer) { - BUG_ON(timer_pending(timer)); + if (WARN_ON_ONCE(timer_pending(timer))) + return; __mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING); } EXPORT_SYMBOL(add_timer); @@ -1210,7 +1211,8 @@ void add_timer_on(struct timer_list *tim struct timer_base *new_base, *base; unsigned long flags; - BUG_ON(timer_pending(timer) || !timer->function); + if (WARN_ON_ONCE(timer_pending(timer) || !timer->function)) + return; new_base = get_timer_cpu_base(timer->flags, cpu); @@ -2017,8 +2019,6 @@ int timers_dead_cpu(unsigned int cpu) struct timer_base *new_base; int b, i; - BUG_ON(cpu_online(cpu)); - for (b = 0; b < NR_BASES; b++) { old_base = per_cpu_ptr(&timer_bases[b], cpu); new_base = get_cpu_ptr(&timer_bases[b]); @@ -2035,7 +2035,8 @@ int timers_dead_cpu(unsigned int cpu) */ forward_timer_base(new_base); - BUG_ON(old_base->running_timer); + WARN_ON_ONCE(old_base->running_timer); + old_base->running_timer = NULL; for (i = 0; i < WHEEL_SIZE; i++) migrate_timer_list(new_base, old_base->vectors + i); From patchwork Tue Nov 22 17:44:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052598 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7594FC4332F for ; Tue, 22 Nov 2022 17:45:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234315AbiKVRpn (ORCPT ); Tue, 22 Nov 2022 12:45:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234306AbiKVRpV (ORCPT ); Tue, 22 Nov 2022 12:45:21 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7198A781B1; Tue, 22 Nov 2022 09:44:57 -0800 (PST) Message-ID: <20221122173648.501792201@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139096; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ZX6HSxA/fzywS26fdVBXIAqlyqEavuJZwMJ+1GlZUJE=; b=Uq4N/5Kq2rTIh2JXEZXuPxfOVWS0gFxZtIFLQc1pSPfWuTvNNfJy/Dzq0QImJxGBfq3fE0 Hp33OrEiK7oR/iq2UpBNbmnrMG+CbxXTXhMR+MILa5NCR01AM6FinflhMsLZbVqz+jPN7N yFVY/emNB3uUOawQJkWUCd309mv4+aZSPPkEth6ImxrVW+xRnqFZevwIccbdfrv344grqR Pe1cyBe3BQ0vjiRFOnm0e/V7/Ca9jt/4PiBZ6uTKCq3CGruqXVcaEv/+CQ8NdAOWhmk3sL 3SLgNEp52MlPuIHolCVLCvGkDCFB9pbm8aJ4IqOU/nFttAHoSFJLByEbA1ihxw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139096; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ZX6HSxA/fzywS26fdVBXIAqlyqEavuJZwMJ+1GlZUJE=; b=WLEMe+0gph+V95PFjvurR1K3iNHD9ctXojNI4KVxnvllVDftjqDzYWtAaGM5k4yl6EXTC5 0KC6PcZutiuYevDw== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 07/17] timers: Update kernel-doc for various functions References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:55 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The kernel-doc of timer related functions is partially uncomprehensible word salad. Rewrite it to make it useful. Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck --- V2: Refined comments (Steven) --- kernel/time/timer.c | 148 ++++++++++++++++++++++++++++++---------------------- 1 file changed, 88 insertions(+), 60 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1121,14 +1121,16 @@ static inline int } /** - * mod_timer_pending - modify a pending timer's timeout - * @timer: the pending timer to be modified - * @expires: new timeout in jiffies - * - * mod_timer_pending() is the same for pending timers as mod_timer(), - * but will not re-activate and modify already deleted timers. - * - * It is useful for unserialized use of timers. + * mod_timer_pending - Modify a pending timer's timeout + * @timer: The pending timer to be modified + * @expires: New absolute timeout in jiffies + * + * mod_timer_pending() is the same for pending timers as mod_timer(), but + * will not activate inactive timers. + * + * Return: + * * %0 - The timer was inactive and not modified + * * %1 - The timer was active and requeued to expire at @expires */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) { @@ -1137,24 +1139,27 @@ int mod_timer_pending(struct timer_list EXPORT_SYMBOL(mod_timer_pending); /** - * mod_timer - modify a timer's timeout - * @timer: the timer to be modified - * @expires: new timeout in jiffies - * - * mod_timer() is a more efficient way to update the expire field of an - * active timer (if the timer is inactive it will be activated) + * mod_timer - Modify a timer's timeout + * @timer: The timer to be modified + * @expires: New absolute timeout in jiffies * * mod_timer(timer, expires) is equivalent to: * * del_timer(timer); timer->expires = expires; add_timer(timer); * + * mod_timer() is more efficient than the above open coded sequence. In + * case that the timer is inactive, the del_timer() part is a NOP. The + * timer is in any case activated with the new expiry time @expires. + * * Note that if there are multiple unserialized concurrent users of the * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * - * The function returns whether it has modified a pending timer or not. - * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an - * active timer returns 1.) + * Return: + * * %0 - The timer was inactive and started + * * %1 - The timer was active and requeued to expire at @expires or + * the timer was active and not modified because @expires did + * not change the effective expiry time */ int mod_timer(struct timer_list *timer, unsigned long expires) { @@ -1165,11 +1170,18 @@ EXPORT_SYMBOL(mod_timer); /** * timer_reduce - Modify a timer's timeout if it would reduce the timeout * @timer: The timer to be modified - * @expires: New timeout in jiffies + * @expires: New absolute timeout in jiffies * * timer_reduce() is very similar to mod_timer(), except that it will only - * modify a running timer if that would reduce the expiration time (it will - * start a timer that isn't running). + * modify an enqueued timer if that would reduce the expiration time. If + * @timer is not enqueued it starts the timer. + * + * Return: + * * %0 - The timer was inactive and started + * * %1 - The timer was active and requeued to expire at @expires or + * the timer was active and not modified because @expires + * did not change the effective expiry time such that the + * timer would expire earlier than already scheduled */ int timer_reduce(struct timer_list *timer, unsigned long expires) { @@ -1178,18 +1190,18 @@ int timer_reduce(struct timer_list *time EXPORT_SYMBOL(timer_reduce); /** - * add_timer - start a timer - * @timer: the timer to be added + * add_timer - Start a timer + * @timer: The timer to be started * - * The kernel will do a ->function(@timer) callback from the - * timer interrupt at the ->expires point in the future. The - * current time is 'jiffies'. + * Start @timer to expire at @timer->expires in the future. @timer->expires + * is the absolute expiry time measured in 'jiffies'. When the timer expires + * timer->function(timer) will be invoked from soft interrupt context. * - * The timer's ->expires, ->function fields must be set prior calling this - * function. + * The @timer->expires and @timer->function fields must be set prior + * to calling this function. * - * Timers with an ->expires field in the past will be executed in the next - * timer tick. + * If @timer->expires is already in the past @timer will be queued to + * expire at the next timer tick. */ void add_timer(struct timer_list *timer) { @@ -1200,11 +1212,12 @@ void add_timer(struct timer_list *timer) EXPORT_SYMBOL(add_timer); /** - * add_timer_on - start a timer on a particular CPU - * @timer: the timer to be added - * @cpu: the CPU to start it on + * add_timer_on - Start a timer on a particular CPU + * @timer: The timer to be started + * @cpu: The CPU to start it on * - * This is not very scalable on SMP. Double adds are not possible. + * This can only operate on an inactive timer. Attempts to invoke this on + * an active timer are rejected with a warning. */ void add_timer_on(struct timer_list *timer, int cpu) { @@ -1240,15 +1253,18 @@ void add_timer_on(struct timer_list *tim EXPORT_SYMBOL_GPL(add_timer_on); /** - * del_timer - deactivate a timer. - * @timer: the timer to be deactivated - * - * del_timer() deactivates a timer - this works on both active and inactive - * timers. + * del_timer - Deactivate a timer. + * @timer: The timer to be deactivated * - * The function returns whether it has deactivated a pending timer or not. - * (ie. del_timer() of an inactive timer returns 0, del_timer() of an - * active timer returns 1.) + * The function only deactivates a pending timer, but contrary to + * del_timer_sync() it does not take into account whether the timers + * callback function is concurrently executed on a different CPU or not. + * It neither prevents rearming of the timer. If @timer can be rearmed + * concurrently then the return value of this function is meaningless. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated */ int del_timer(struct timer_list *timer) { @@ -1270,10 +1286,19 @@ EXPORT_SYMBOL(del_timer); /** * try_to_del_timer_sync - Try to deactivate a timer - * @timer: timer to delete + * @timer: Timer to deactivate * - * This function tries to deactivate a timer. Upon successful (ret >= 0) - * exit the timer is not queued and the handler is not running on any CPU. + * This function tries to deactivate a timer. On success the timer is not + * queued and the timer callback function is not running on any CPU. + * + * This function does not guarantee that the timer cannot be rearmed right + * after dropping the base lock. That needs to be prevented by the calling + * code if necessary. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated + * * %-1 - The timer callback function is running on a different CPU */ int try_to_del_timer_sync(struct timer_list *timer) { @@ -1369,23 +1394,19 @@ static inline void del_timer_wait_runnin #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) /** - * del_timer_sync - deactivate a timer and wait for the handler to finish. - * @timer: the timer to be deactivated - * - * This function only differs from del_timer() on SMP: besides deactivating - * the timer it also makes sure the handler has finished executing on other - * CPUs. + * del_timer_sync - Deactivate a timer and wait for the handler to finish. + * @timer: The timer to be deactivated * * Synchronization rules: Callers must prevent restarting of the timer, * otherwise this function is meaningless. It must not be called from * interrupt contexts unless the timer is an irqsafe one. The caller must - * not hold locks which would prevent completion of the timer's - * handler. The timer's handler must not call add_timer_on(). Upon exit the - * timer is not queued and the handler is not running on any CPU. - * - * Note: For !irqsafe timers, you must not hold locks that are held in - * interrupt context while calling this function. Even if the lock has - * nothing to do with the timer in question. Here's why:: + * not hold locks which would prevent completion of the timer's callback + * function. The timer's handler must not call add_timer_on(). Upon exit + * the timer is not queued and the handler is not running on any CPU. + * + * For !irqsafe timers, the caller must not hold locks that are held in + * interrupt context. Even if the lock has nothing to do with the timer in + * question. Here's why:: * * CPU0 CPU1 * ---- ---- @@ -1399,10 +1420,17 @@ static inline void del_timer_wait_runnin * while (base->running_timer == mytimer); * * Now del_timer_sync() will never return and never release somelock. - * The interrupt on the other CPU is waiting to grab somelock but - * it has interrupted the softirq that CPU0 is waiting to finish. + * The interrupt on the other CPU is waiting to grab somelock but it has + * interrupted the softirq that CPU0 is waiting to finish. * - * The function returns whether it has deactivated a pending timer or not. + * This function cannot guarantee that the timer is not rearmed again by + * some concurrent or preempting code, right after it dropped the base + * lock. If there is the possibility of a concurrent rearm then the return + * value of the function is meaningless. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated */ int del_timer_sync(struct timer_list *timer) { From patchwork Tue Nov 22 17:44:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052599 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C05E9C43219 for ; Tue, 22 Nov 2022 17:45:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233978AbiKVRpp (ORCPT ); Tue, 22 Nov 2022 12:45:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234366AbiKVRp2 (ORCPT ); Tue, 22 Nov 2022 12:45:28 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A9E8D9F; Tue, 22 Nov 2022 09:44:59 -0800 (PST) Message-ID: <20221122173648.560770928@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139097; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=EMpM2Y9+AZ3Mkc+gVMKWk6eghahsVVjAJyXVQ6CR7oc=; b=jOfQSKgiI43Mey5tMtwdwq5HcuqumunlijHH9jFhIuNmnqNMa09hn7oPyucrb3Fb7Hy247 sBgZzHiczM2XHBKwQ/4ZYgkb4s+rZsXYUF3Hlb5PGQpHYZMAcnEqweoxl780oo2E/ncE12 TMxE0d0PhCN97Le4qcdR6JQdxsiQn14ANd53XDmF449szrYZKxUH2Pb664Sf0h4nlVhh0T iVDuKH07E3dFD9TiKVSrbxfy62RC2mLgBJFWStGvY+tVP7RsoeKUtLxXtgQdSFS8Eax6aP QOpN12SrPjoFzA6VWLkFtiCkDix5G133PH+yLVfd6KG+DRNqCUrt/OQ4vhBXxA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139097; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=EMpM2Y9+AZ3Mkc+gVMKWk6eghahsVVjAJyXVQ6CR7oc=; b=BWp8Zh//+2G8dMEG6BXVGDbM34z0AVD4jWkQgirweP06NXhIGCtYfEjeg8i9J72JprjMmF MOrJTm31/GbXkIBg== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 08/17] timers: Use del_timer_sync() even on UP References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:57 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org del_timer_sync() is assumed to be pointless on uniprocessor systems and can be mapped to del_timer() because in theory del_timer() can never be invoked while the timer callback function is executed. This is not entirely true because del_timer() can be invoked from interrupt context and therefore hit in the middle of a running timer callback. Contrary to that del_timer_sync() is not allowed to be invoked from interrupt context unless the affected timer is marked with TIMER_IRQSAFE. del_timer_sync() has proper checks in place to detect such a situation. Give up on the UP optimization and make del_timer_sync() unconditionally available. Co-developed-by: Steven Rostedt Signed-off-by: Steven Rostedt Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org --- include/linux/timer.h | 7 +------ kernel/time/timer.c | 2 -- 2 files changed, 1 insertion(+), 8 deletions(-) --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -183,12 +183,7 @@ extern int timer_reduce(struct timer_lis extern void add_timer(struct timer_list *timer); extern int try_to_del_timer_sync(struct timer_list *timer); - -#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) - extern int del_timer_sync(struct timer_list *timer); -#else -# define del_timer_sync(t) del_timer(t) -#endif +extern int del_timer_sync(struct timer_list *timer); extern void init_timers(void); struct hrtimer; --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1392,7 +1392,6 @@ static inline void timer_sync_wait_runni static inline void del_timer_wait_running(struct timer_list *timer) { } #endif -#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) /** * del_timer_sync - Deactivate a timer and wait for the handler to finish. * @timer: The timer to be deactivated @@ -1473,7 +1472,6 @@ int del_timer_sync(struct timer_list *ti return ret; } EXPORT_SYMBOL(del_timer_sync); -#endif static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *), From patchwork Tue Nov 22 17:44:58 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052601 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED99CC43217 for ; Tue, 22 Nov 2022 17:45:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234539AbiKVRps (ORCPT ); Tue, 22 Nov 2022 12:45:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234425AbiKVRp3 (ORCPT ); Tue, 22 Nov 2022 12:45:29 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A90347AF7A; Tue, 22 Nov 2022 09:45:00 -0800 (PST) Message-ID: <20221122173648.619071341@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139099; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=loWOeteSDfXqDwCwhR8PkMj0fJ4Wcn9TP/qRmPXVBa4=; b=0hGO5Wk0pIFm1S0qXeQ7PdXOz5PGq9RcqJf+EmVCFF9bex2AVxb7gkfQnxHICeUi7/Ofuh 48V9LXYVsWvLvrvtLAc0iwSq/iSlDCxv91iy9EKhkMlJsVs5rEkw8/mNfElda3OynSfpol LI8lc6naiyJ1JLUj0ip9QTVlns8m+Ac4IZW7XvnECZ6oE45BuisMRZyJRaEwaMadBWEPDc 2lgqKklCAGeS+HNbHTasKvZQ7hypSXUsAmYEOPBviKCesT1hq21R5jefyA8lK78lPHXWaV 8VS1tyDeFLdoLFs3Rj3jvJ3ij/YuZ3PJ3ksst1VziEqbsO9wSs1odqw2PynWjw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139099; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=loWOeteSDfXqDwCwhR8PkMj0fJ4Wcn9TP/qRmPXVBa4=; b=kzKXKPXw/BGYqj/wvLmudmM7Vc295HgkEEBR1suH31GOdddL+BaN6HBZIeYF6GHCSfOgG7 6M9XpNmCuBPLjoAQ== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 09/17] timers: Rename del_timer_sync() to timer_delete_sync() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:44:58 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The timer related functions do not have a strict timer_ prefixed namespace which is really annoying. Rename del_timer_sync() to timer_delete_sync() and provide del_timer_sync() as a wrapper. Document that del_timer_sync() is not for new code. Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt (Google) Tested-by: Guenter Roeck --- include/linux/timer.h | 15 ++++++++++++++- kernel/time/timer.c | 18 +++++++++--------- 2 files changed, 23 insertions(+), 10 deletions(-) --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -183,7 +183,20 @@ extern int timer_reduce(struct timer_lis extern void add_timer(struct timer_list *timer); extern int try_to_del_timer_sync(struct timer_list *timer); -extern int del_timer_sync(struct timer_list *timer); +extern int timer_delete_sync(struct timer_list *timer); + +/** + * del_timer_sync - Delete a pending timer and wait for a running callback + * @timer: The timer to be deleted + * + * See timer_delete_sync() for detailed explanation. + * + * Do not use in new code. Use timer_delete_sync() instead. + */ +static inline int del_timer_sync(struct timer_list *timer) +{ + return timer_delete_sync(timer); +} extern void init_timers(void); struct hrtimer; --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1083,7 +1083,7 @@ static inline int /* * We are trying to schedule the timer on the new base. * However we can't change timer's base while it is running, - * otherwise del_timer_sync() can't detect that the timer's + * otherwise timer_delete_sync() can't detect that the timer's * handler yet has not finished. This also guarantees that the * timer is serialized wrt itself. */ @@ -1257,7 +1257,7 @@ EXPORT_SYMBOL_GPL(add_timer_on); * @timer: The timer to be deactivated * * The function only deactivates a pending timer, but contrary to - * del_timer_sync() it does not take into account whether the timers + * timer_delete_sync() it does not take into account whether the timers * callback function is concurrently executed on a different CPU or not. * It neither prevents rearming of the timer. If @timer can be rearmed * concurrently then the return value of this function is meaningless. @@ -1393,7 +1393,7 @@ static inline void del_timer_wait_runnin #endif /** - * del_timer_sync - Deactivate a timer and wait for the handler to finish. + * timer_delete_sync - Deactivate a timer and wait for the handler to finish. * @timer: The timer to be deactivated * * Synchronization rules: Callers must prevent restarting of the timer, @@ -1415,10 +1415,10 @@ static inline void del_timer_wait_runnin * spin_lock_irq(somelock); * * spin_lock(somelock); - * del_timer_sync(mytimer); + * timer_delete_sync(mytimer); * while (base->running_timer == mytimer); * - * Now del_timer_sync() will never return and never release somelock. + * Now timer_delete_sync() will never return and never release somelock. * The interrupt on the other CPU is waiting to grab somelock but it has * interrupted the softirq that CPU0 is waiting to finish. * @@ -1431,7 +1431,7 @@ static inline void del_timer_wait_runnin * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -int del_timer_sync(struct timer_list *timer) +int timer_delete_sync(struct timer_list *timer) { int ret; @@ -1471,7 +1471,7 @@ int del_timer_sync(struct timer_list *ti return ret; } -EXPORT_SYMBOL(del_timer_sync); +EXPORT_SYMBOL(timer_delete_sync); static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *), @@ -1493,8 +1493,8 @@ static void call_timer_fn(struct timer_l #endif /* * Couple the lock chain with the lock chain at - * del_timer_sync() by acquiring the lock_map around the fn() - * call here and in del_timer_sync(). + * timer_delete_sync() by acquiring the lock_map around the fn() + * call here and in timer_delete_sync(). */ lock_map_acquire(&lockdep_map); From patchwork Tue Nov 22 17:45:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052600 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC6FAC4321E for ; Tue, 22 Nov 2022 17:45:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234532AbiKVRpq (ORCPT ); Tue, 22 Nov 2022 12:45:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234423AbiKVRp3 (ORCPT ); Tue, 22 Nov 2022 12:45:29 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DF427D51E; Tue, 22 Nov 2022 09:45:02 -0800 (PST) Message-ID: <20221122173648.679936164@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139100; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=1Q8N97xZ72xYy6vaaOLnyE0AxAlIzspsYSXG7581VxQ=; b=IkD8ianPoPQldqkb3P9hR8nlIuHVqEK6gsxCD0j71FFDedH2uho5vWyvLz+Mq+EYVTG0Pl OwFR45jUL/j9LDD8rBl+552yobOcxn+8xuKQeeGANg27GP/QwCZVOIj/KiNxqbFJt+wwZE UHx8KLgVNnFaAHK40vW0/SIxalv938uEETX9ps7oZQOm0MmKD70z2MBnOmvS2vcEQP6+sa CazvwU2GXkqt8wFkRZ9tLY/YaQI1AqTEePpOsKCV9DOKFkWqyAt9HC6SCjY93mfl2E2T2v nMT5KVujR9X7NI4UhbCoaoe0dQg7HVAUdBQIAJ/TY2NWv5VlVSe6IzsKF9zftQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139100; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=1Q8N97xZ72xYy6vaaOLnyE0AxAlIzspsYSXG7581VxQ=; b=9BIIdv4TvKJqzaHSdYedMWcor4slJm9zpeR2PZ5ms6tHSxp7lUbb90kMBJCRQrZCMelDMS /nOYXb6GFrm1BqAA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 10/17] timers: Rename del_timer() to timer_delete() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:00 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The timer related functions do not have a strict timer_ prefixed namespace which is really annoying. Rename del_timer() to timer_delete() and provide del_timer() as a wrapper. Document that del_timer() is not for new code. Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt (Google) Tested-by: Guenter Roeck --- include/linux/timer.h | 15 ++++++++++++++- kernel/time/timer.c | 6 +++--- 2 files changed, 17 insertions(+), 4 deletions(-) --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -169,7 +169,6 @@ static inline int timer_pending(const st } extern void add_timer_on(struct timer_list *timer, int cpu); -extern int del_timer(struct timer_list * timer); extern int mod_timer(struct timer_list *timer, unsigned long expires); extern int mod_timer_pending(struct timer_list *timer, unsigned long expires); extern int timer_reduce(struct timer_list *timer, unsigned long expires); @@ -184,6 +183,7 @@ extern void add_timer(struct timer_list extern int try_to_del_timer_sync(struct timer_list *timer); extern int timer_delete_sync(struct timer_list *timer); +extern int timer_delete(struct timer_list *timer); /** * del_timer_sync - Delete a pending timer and wait for a running callback @@ -198,6 +198,19 @@ static inline int del_timer_sync(struct return timer_delete_sync(timer); } +/** + * del_timer - Delete a pending timer + * @timer: The timer to be deleted + * + * See timer_delete() for detailed explanation. + * + * Do not use in new code. Use timer_delete() instead. + */ +static inline int del_timer(struct timer_list *timer) +{ + return timer_delete(timer); +} + extern void init_timers(void); struct hrtimer; extern enum hrtimer_restart it_real_fn(struct hrtimer *); --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1253,7 +1253,7 @@ void add_timer_on(struct timer_list *tim EXPORT_SYMBOL_GPL(add_timer_on); /** - * del_timer - Deactivate a timer. + * timer_delete - Deactivate a timer. * @timer: The timer to be deactivated * * The function only deactivates a pending timer, but contrary to @@ -1266,7 +1266,7 @@ EXPORT_SYMBOL_GPL(add_timer_on); * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -int del_timer(struct timer_list *timer) +int timer_delete(struct timer_list *timer) { struct timer_base *base; unsigned long flags; @@ -1282,7 +1282,7 @@ int del_timer(struct timer_list *timer) return ret; } -EXPORT_SYMBOL(del_timer); +EXPORT_SYMBOL(timer_delete); /** * try_to_del_timer_sync - Try to deactivate a timer From patchwork Tue Nov 22 17:45:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052602 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DBA6C4332F for ; Tue, 22 Nov 2022 17:46:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234568AbiKVRqF (ORCPT ); Tue, 22 Nov 2022 12:46:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233878AbiKVRpl (ORCPT ); Tue, 22 Nov 2022 12:45:41 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA4A27CB84; Tue, 22 Nov 2022 09:45:03 -0800 (PST) Message-ID: <20221122173648.737720888@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139102; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=y8/Vu8FUleXD3Q2rM81FfgxNTEn3ZV50/HwHiGfKzVY=; b=FseicS90xmf4gF1/tgcarYUG2IWEALo5wjRDB5bPlMl5usMOp61n8lHSQXUIyyfy+AVZWt iM/QqKgTQH8STr2H2lrM9Xq1hciVp6V5y8RujYnhgjUAsZdI3wCpwrpVzG88Oc9b1skgsr odLIAshZxWvWhd8Jx5W1nb7nWzQh6x2BBkIp5R0L6DbPU8bNLhu0KgFqQBv1DOo45wOKAw ZXnzBWLDK/DC85WTrCTi5cUnDvM3UFLDHRDYdXhfkArYoxZxp8w1+2JhIeTmpfWgRAsm29 z3xJzrfkUdt1RG7KN0QX7t5oh/oofsc3JWYZr+e5OPmrlxLj/mo7o8b6hyf6TA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139102; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=y8/Vu8FUleXD3Q2rM81FfgxNTEn3ZV50/HwHiGfKzVY=; b=U3tuUlrXkU0PYik4DgaMpL9uwmedgy2Vu16MaSbtxwVzRVFHlkPCeYS3NdwrZUK+ht15f+ pjQXICn3DDkGOBCA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 11/17] Documentation: Replace del_timer/del_timer_sync() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:01 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Adjust to the new preferred function names. Suggested-by: Steven Rostedt Signed-off-by: Thomas Gleixner --- Documentation/RCU/Design/Requirements/Requirements.rst | 2 +- Documentation/core-api/local_ops.rst | 2 +- Documentation/kernel-hacking/locking.rst | 11 +++++------ Documentation/timers/hrtimers.rst | 2 +- Documentation/translations/it_IT/kernel-hacking/locking.rst | 10 +++++----- Documentation/translations/zh_CN/core-api/local_ops.rst | 2 +- 6 files changed, 14 insertions(+), 15 deletions(-) --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1858,7 +1858,7 @@ unloaded. After a given module has been one of its functions results in a segmentation fault. The module-unload functions must therefore cancel any delayed calls to loadable-module functions, for example, any outstanding mod_timer() must be dealt -with via del_timer_sync() or similar. +with via timer_delete_sync() or similar. Unfortunately, there is no way to cancel an RCU callback; once you invoke call_rcu(), the callback function is eventually going to be --- a/Documentation/core-api/local_ops.rst +++ b/Documentation/core-api/local_ops.rst @@ -191,7 +191,7 @@ Here is a sample module which implements static void __exit test_exit(void) { - del_timer_sync(&test_timer); + timer_delete_sync(&test_timer); } module_init(test_init); --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -967,7 +967,7 @@ If you want to destroy the entire collec while (list) { struct foo *next = list->next; - del_timer(&list->timer); + timer_delete(&list->timer); kfree(list); list = next; } @@ -981,7 +981,7 @@ the lock after we spin_unlock_bh(), and the element (which has already been freed!). This can be avoided by checking the result of -del_timer(): if it returns 1, the timer has been deleted. +timer_delete(): if it returns 1, the timer has been deleted. If 0, it means (in this case) that it is currently running, so we can do:: @@ -990,7 +990,7 @@ If 0, it means (in this case) that it is while (list) { struct foo *next = list->next; - if (!del_timer(&list->timer)) { + if (!timer_delete(&list->timer)) { /* Give timer a chance to delete this */ spin_unlock_bh(&list_lock); goto retry; @@ -1005,8 +1005,7 @@ If 0, it means (in this case) that it is Another common problem is deleting timers which restart themselves (by calling add_timer() at the end of their timer function). Because this is a fairly common case which is prone to races, you should -use del_timer_sync() (``include/linux/timer.h``) to -handle this case. +use timer_delete_sync() (``include/linux/timer.h``) to handle this case. Locking Speed ============= @@ -1334,7 +1333,7 @@ lock. - kfree() -- add_timer() and del_timer() +- add_timer() and timer_delete() Mutex API reference =================== --- a/Documentation/timers/hrtimers.rst +++ b/Documentation/timers/hrtimers.rst @@ -118,7 +118,7 @@ existing timer wheel code, as it is matu was not really a win, due to the different data structures. Also, the hrtimer functions now have clearer behavior and clearer names - such as hrtimer_try_to_cancel() and hrtimer_cancel() [which are roughly -equivalent to del_timer() and del_timer_sync()] - so there's no direct +equivalent to timer_delete() and timer_delete_sync()] - so there's no direct 1:1 mapping between them on the algorithmic level, and thus no real potential for code sharing either. --- a/Documentation/translations/it_IT/kernel-hacking/locking.rst +++ b/Documentation/translations/it_IT/kernel-hacking/locking.rst @@ -990,7 +990,7 @@ Se volete eliminare l'intera collezione while (list) { struct foo *next = list->next; - del_timer(&list->timer); + timer_delete(&list->timer); kfree(list); list = next; } @@ -1003,7 +1003,7 @@ e prenderà il *lock* solo dopo spin_unl di eliminare il suo oggetto (che però è già stato eliminato). Questo può essere evitato controllando il valore di ritorno di -del_timer(): se ritorna 1, il temporizzatore è stato già +timer_delete(): se ritorna 1, il temporizzatore è stato già rimosso. Se 0, significa (in questo caso) che il temporizzatore è in esecuzione, quindi possiamo fare come segue:: @@ -1012,7 +1012,7 @@ rimosso. Se 0, significa (in questo caso while (list) { struct foo *next = list->next; - if (!del_timer(&list->timer)) { + if (!timer_delete(&list->timer)) { /* Give timer a chance to delete this */ spin_unlock_bh(&list_lock); goto retry; @@ -1026,7 +1026,7 @@ rimosso. Se 0, significa (in questo caso Un altro problema è l'eliminazione dei temporizzatori che si riavviano da soli (chiamando add_timer() alla fine della loro esecuzione). Dato che questo è un problema abbastanza comune con una propensione -alle corse critiche, dovreste usare del_timer_sync() +alle corse critiche, dovreste usare timer_delete_sync() (``include/linux/timer.h``) per gestire questo caso. Velocità della sincronizzazione @@ -1372,7 +1372,7 @@ contesto, o trattenendo un qualsiasi *lo - kfree() -- add_timer() e del_timer() +- add_timer() e timer_delete() Riferimento per l'API dei Mutex =============================== --- a/Documentation/translations/zh_CN/core-api/local_ops.rst +++ b/Documentation/translations/zh_CN/core-api/local_ops.rst @@ -185,7 +185,7 @@ UP之间没有不同的行为，在你� static void __exit test_exit(void) { - del_timer_sync(&test_timer); + timer_delete_sync(&test_timer); } module_init(test_init); From patchwork Tue Nov 22 17:45:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052603 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65CA1C433FE for ; Tue, 22 Nov 2022 17:46:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234588AbiKVRqI (ORCPT ); Tue, 22 Nov 2022 12:46:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234281AbiKVRpl (ORCPT ); Tue, 22 Nov 2022 12:45:41 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 624A77D501; Tue, 22 Nov 2022 09:45:05 -0800 (PST) Message-ID: <20221122173648.793640919@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139104; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=EajXJEzifJO2k3UDHuOk2BYCYQZRqzlObtc+LJK0BY4=; b=4qp6Ri4H+/fn2hAu4yl6rudwb18lvNrlDHP1RAa1J3h7fh8X3hnSoEEpTRSXuZsbGJD0cO U+TTXU2Oosy7AA3wOXkhWY83jco6qccmDLHM0Q87uQDUzXSbubDb9JLaZIECZ8/+6CHDfY I8S7c7yKbRvqStUVlThPnz/x+WzRq2dTVAUSkC56MiT0cyi6UpxhJZbLFfo6Qqo+9bjtYx U180hmYUzyFzFk+3OZHhkKncuWBOCwGC333cReiWhLR8I4XCqnLZLLwBGpmaNtJVqTxgAC GPVxGKu09LBmHZbaqIX6XVcdkx/wWn2neu3/aiZmud+unE0XGp6S8kNBt/4XKw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139104; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=EajXJEzifJO2k3UDHuOk2BYCYQZRqzlObtc+LJK0BY4=; b=JpNvIWeSy9xrBPNn4gfk7Ak7Gpwm4IyMV6VPS/4JjGs3JpEGB2IJHu29W7xv/tTc/XRnZA VPZ+uOAvYzFPUyCQ== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 12/17] timers: Silently ignore timers with a NULL function References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:03 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers is not trivial. In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so it to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request. In preparation for that replace the warnings in the relevant code pathes with checks for timer->function == NULL and discard the rearm request silently. Add debug_assert_init() instead of the WARN_ON_ONCE(!timer->function) checks so that debug objects can warn about non-initialized timers. If developers fail to enable debug objects and then waste lots of time to figure out why their non-initialized timer is not firing, they deserve it. Co-developed-by: Steven Rostedt Signed-off-by: Steven Rostedt Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org --- V2: Use continue instead of return and amend the return value docs (Steven) --- kernel/time/timer.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 55 insertions(+), 5 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1017,7 +1017,7 @@ static inline int unsigned int idx = UINT_MAX; int ret = 0; - BUG_ON(!timer->function); + debug_assert_init(timer); /* * This is a common optimization triggered by the networking code - if @@ -1044,6 +1044,14 @@ static inline int * dequeue/enqueue dance. */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base); if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) && @@ -1070,6 +1078,14 @@ static inline int } } else { base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base); } @@ -1128,8 +1144,12 @@ static inline int * mod_timer_pending() is the same for pending timers as mod_timer(), but * will not activate inactive timers. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and not modified + * * %0 - The timer was inactive and not modified or was is in + * shutdown state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) @@ -1155,8 +1175,12 @@ EXPORT_SYMBOL(mod_timer_pending); * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * + * If @timer->function == NULL then the start operation is silently + * discarded, the return value is 0 and meaningless. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was is in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires did * not change the effective expiry time @@ -1176,8 +1200,12 @@ EXPORT_SYMBOL(mod_timer); * modify an enqueued timer if that would reduce the expiration time. If * @timer is not enqueued it starts the timer. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was is in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires * did not change the effective expiry time such that the @@ -1202,6 +1230,9 @@ EXPORT_SYMBOL(timer_reduce); * * If @timer->expires is already in the past @timer will be queued to * expire at the next timer tick. + * + * If @timer->function == NULL then the start operation is silently + * discarded. */ void add_timer(struct timer_list *timer) { @@ -1218,13 +1249,18 @@ EXPORT_SYMBOL(add_timer); * * This can only operate on an inactive timer. Attempts to invoke this on * an active timer are rejected with a warning. + * + * If @timer->function == NULL then the start operation is silently + * discarded. */ void add_timer_on(struct timer_list *timer, int cpu) { struct timer_base *new_base, *base; unsigned long flags; - if (WARN_ON_ONCE(timer_pending(timer) || !timer->function)) + debug_assert_init(timer); + + if (WARN_ON_ONCE(timer_pending(timer))) return; new_base = get_timer_cpu_base(timer->flags, cpu); @@ -1235,6 +1271,13 @@ void add_timer_on(struct timer_list *tim * wrong base locked. See lock_timer_base(). */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated while + * holding base lock to prevent a race against the shutdown code. + */ + if (!timer->function) + goto out_unlock; + if (base != new_base) { timer->flags |= TIMER_MIGRATING; @@ -1248,6 +1291,7 @@ void add_timer_on(struct timer_list *tim debug_timer_activate(timer); internal_add_timer(base, timer); +out_unlock: raw_spin_unlock_irqrestore(&base->lock, flags); } EXPORT_SYMBOL_GPL(add_timer_on); @@ -1537,6 +1581,12 @@ static void expire_timers(struct timer_b fn = timer->function; + if (WARN_ON_ONCE(!fn)) { + /* Should never happen. Emphasis on should! */ + base->running_timer = NULL; + continue; + } + if (timer->flags & TIMER_IRQSAFE) { raw_spin_unlock(&base->lock); call_timer_fn(timer, fn, baseclk); From patchwork Tue Nov 22 17:45:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052604 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DEC00C43217 for ; Tue, 22 Nov 2022 17:46:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234511AbiKVRqW (ORCPT ); Tue, 22 Nov 2022 12:46:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234517AbiKVRpo (ORCPT ); Tue, 22 Nov 2022 12:45:44 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85AC782BC3; Tue, 22 Nov 2022 09:45:08 -0800 (PST) Message-ID: <20221122173648.849454220@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=FhfrDrd2SIdwsUU/mnu4VC/j8yhsPAhYg8PH8x3o4f8=; b=h3OzbbsnMY4WNTR5FAlmXYF3ZNnCD+EoUf+SIaR/RJ+zceXB7RwDR1GVgOsDYFiD5+GNQg 0hRhNcwGp2q0wDxf8rLFKPzFykNuzCpuMZ9pzMkkcVphJYINcpVT8RDBNAb5VUXSiMRLqc xSac9Ufm311E13DVjcT5RSbMpADzuf4ffSxL8RfhAKnDsAscOiUe9jpRU0LjjRLFp3o0Wr FRMsJckn5xLvVZeqhIvioGh4vrcWXmbHObObkzaOvD/rAcP3lE+oTl0vjaC+p/nhv2D/Rr EMI81eh3bdvvOcRZuaBjEzkO837ywnYxRm8tXliLIgYHzElF+JvPIK3g9otuNg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=FhfrDrd2SIdwsUU/mnu4VC/j8yhsPAhYg8PH8x3o4f8=; b=ms+XQH5b7Yjshnr/nlQBJV0Zwry/ked33KWOhWX6J0W5ARgT/K4i7lNc1T9FW3Nw/2oiq/ L5ux23S1X8+1KrAw== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 13/17] timers: Split [try_to_]del_timer[_sync]() to prepare for shutdown mode References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:05 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers is not trivial. In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so it to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request. Split the inner workings of try_do_del_timer_sync(), del_timer_sync() and del_timer() into helper functions to prepare for implementing the shutdown functionality. No functional change. Co-developed-by: Steven Rostedt Signed-off-by: Steven Rostedt Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org --- kernel/time/timer.c | 143 +++++++++++++++++++++++++++++++++------------------- 1 file changed, 92 insertions(+), 51 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1297,20 +1297,14 @@ void add_timer_on(struct timer_list *tim EXPORT_SYMBOL_GPL(add_timer_on); /** - * timer_delete - Deactivate a timer. + * __timer_delete - Internal function: Deactivate a timer. * @timer: The timer to be deactivated * - * The function only deactivates a pending timer, but contrary to - * timer_delete_sync() it does not take into account whether the timers - * callback function is concurrently executed on a different CPU or not. - * It neither prevents rearming of the timer. If @timer can be rearmed - * concurrently then the return value of this function is meaningless. - * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -int timer_delete(struct timer_list *timer) +static int __timer_delete(struct timer_list *timer) { struct timer_base *base; unsigned long flags; @@ -1326,25 +1320,37 @@ int timer_delete(struct timer_list *time return ret; } -EXPORT_SYMBOL(timer_delete); /** - * try_to_del_timer_sync - Try to deactivate a timer - * @timer: Timer to deactivate + * timer_delete - Deactivate a timer. + * @timer: The timer to be deactivated * - * This function tries to deactivate a timer. On success the timer is not - * queued and the timer callback function is not running on any CPU. + * The function only deactivates a pending timer, but contrary to + * timer_delete_sync() it does not take into account whether the timers + * callback function is concurrently executed on a different CPU or not. + * It neither prevents rearming of the timer. If @timer can be rearmed + * concurrently then the return value of this function is meaningless. * - * This function does not guarantee that the timer cannot be rearmed right - * after dropping the base lock. That needs to be prevented by the calling - * code if necessary. + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated + */ +int timer_delete(struct timer_list *timer) +{ + return __timer_delete(timer); +} +EXPORT_SYMBOL(timer_delete); + +/** + * __try_to_del_timer_sync - Internal function: Try to deactivate a timer + * @timer: Timer to deactivate * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated * * %-1 - The timer callback function is running on a different CPU */ -int try_to_del_timer_sync(struct timer_list *timer) +static int __try_to_del_timer_sync(struct timer_list *timer) { struct timer_base *base; unsigned long flags; @@ -1361,6 +1367,27 @@ int try_to_del_timer_sync(struct timer_l return ret; } + +/** + * try_to_del_timer_sync - Try to deactivate a timer + * @timer: Timer to deactivate + * + * This function tries to deactivate a timer. On success the timer is not + * queued and the timer callback function is not running on any CPU. + * + * This function does not guarantee that the timer cannot be rearmed right + * after dropping the base lock. That needs to be prevented by the calling + * code if necessary. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated + * * %-1 - The timer callback function is running on a different CPU + */ +int try_to_del_timer_sync(struct timer_list *timer) +{ + return __try_to_del_timer_sync(timer); +} EXPORT_SYMBOL(try_to_del_timer_sync); #ifdef CONFIG_PREEMPT_RT @@ -1437,45 +1464,15 @@ static inline void del_timer_wait_runnin #endif /** - * timer_delete_sync - Deactivate a timer and wait for the handler to finish. + * __timer_delete_sync - Internal function: Deactivate a timer and wait + * for the handler to finish. * @timer: The timer to be deactivated * - * Synchronization rules: Callers must prevent restarting of the timer, - * otherwise this function is meaningless. It must not be called from - * interrupt contexts unless the timer is an irqsafe one. The caller must - * not hold locks which would prevent completion of the timer's callback - * function. The timer's handler must not call add_timer_on(). Upon exit - * the timer is not queued and the handler is not running on any CPU. - * - * For !irqsafe timers, the caller must not hold locks that are held in - * interrupt context. Even if the lock has nothing to do with the timer in - * question. Here's why:: - * - * CPU0 CPU1 - * ---- ---- - * - * call_timer_fn(); - * base->running_timer = mytimer; - * spin_lock_irq(somelock); - * - * spin_lock(somelock); - * timer_delete_sync(mytimer); - * while (base->running_timer == mytimer); - * - * Now timer_delete_sync() will never return and never release somelock. - * The interrupt on the other CPU is waiting to grab somelock but it has - * interrupted the softirq that CPU0 is waiting to finish. - * - * This function cannot guarantee that the timer is not rearmed again by - * some concurrent or preempting code, right after it dropped the base - * lock. If there is the possibility of a concurrent rearm then the return - * value of the function is meaningless. - * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -int timer_delete_sync(struct timer_list *timer) +static int __timer_delete_sync(struct timer_list *timer) { int ret; @@ -1505,7 +1502,7 @@ int timer_delete_sync(struct timer_list lockdep_assert_preemption_enabled(); do { - ret = try_to_del_timer_sync(timer); + ret = __try_to_del_timer_sync(timer); if (unlikely(ret < 0)) { del_timer_wait_running(timer); @@ -1515,6 +1512,50 @@ int timer_delete_sync(struct timer_list return ret; } + +/** + * timer_delete_sync - Deactivate a timer and wait for the handler to finish. + * @timer: The timer to be deactivated + * + * Synchronization rules: Callers must prevent restarting of the timer, + * otherwise this function is meaningless. It must not be called from + * interrupt contexts unless the timer is an irqsafe one. The caller must + * not hold locks which would prevent completion of the timer's callback + * function. The timer's handler must not call add_timer_on(). Upon exit + * the timer is not queued and the handler is not running on any CPU. + * + * For !irqsafe timers, the caller must not hold locks that are held in + * interrupt context. Even if the lock has nothing to do with the timer in + * question. Here's why:: + * + * CPU0 CPU1 + * ---- ---- + * + * call_timer_fn(); + * base->running_timer = mytimer; + * spin_lock_irq(somelock); + * + * spin_lock(somelock); + * timer_delete_sync(mytimer); + * while (base->running_timer == mytimer); + * + * Now timer_delete_sync() will never return and never release somelock. + * The interrupt on the other CPU is waiting to grab somelock but it has + * interrupted the softirq that CPU0 is waiting to finish. + * + * This function cannot guarantee that the timer is not rearmed again by + * some concurrent or preempting code, right after it dropped the base + * lock. If there is the possibility of a concurrent rearm then the return + * value of the function is meaningless. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated + */ +int timer_delete_sync(struct timer_list *timer) +{ + return __timer_delete_sync(timer); +} EXPORT_SYMBOL(timer_delete_sync); static void call_timer_fn(struct timer_list *timer, From patchwork Tue Nov 22 17:45:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052605 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B67CBC433FE for ; Tue, 22 Nov 2022 17:46:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234617AbiKVRqs (ORCPT ); Tue, 22 Nov 2022 12:46:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234544AbiKVRpv (ORCPT ); Tue, 22 Nov 2022 12:45:51 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8019083E8C; Tue, 22 Nov 2022 09:45:10 -0800 (PST) Message-ID: <20221122173648.905642518@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139107; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=gLm+gmP0TNvnfR1qBgbuyBoK4dp/86Lr9+9waFntgGQ=; b=Z8kspEIOfKATJs3UcxRwM2k75pgP9SyKsjso6xmQ4Gb8pZbon41jWgoAn6o8RHzM+IGTf7 p71csn/qeHc1mBbaeWIxnQYZlDzz9EDLqDC0NBdbQ61oGgJUezFHRGibwIvkmupI8ePAuT l987Iz3GI1+ECpkdUZtHqbgeiD5zLneNUj+DUMXcql5asx9DTwuV+eDjGkpl2Z7raTPxzz beF9khE+7WLElTgYyuTCA8Z02O0zGv5bAGSL4/aVYXnwSkHGcAtBBetm9gJ+ioUj6vozzQ Bb/EA5AnPFXyRgOTWjXlGjEJNkH9HIPqDQU186sDSEmvSxfbASyrxxERX2O4sg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139107; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=gLm+gmP0TNvnfR1qBgbuyBoK4dp/86Lr9+9waFntgGQ=; b=6yNDs5N38sDa/es5IbFSeFCswzyh3jR8EEkQ1PCdia7bpV8wtTy3hONJV982ayPuvg/3OR j5Z9vcP7HRjoTYBA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 14/17] timers: Add shutdown mechanism to the internal functions References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:06 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers is not trivial. In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so it to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request. Add a shutdown argument to the relevant internal functions which makes the actual deactivation code set timer->function to NULL which in turn prevents rearming of the timer. Co-developed-by: Steven Rostedt Signed-off-by: Steven Rostedt Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org --- V2: Add missing commata (Steven) --- kernel/time/timer.c | 64 ++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 55 insertions(+), 9 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1297,14 +1297,21 @@ void add_timer_on(struct timer_list *tim EXPORT_SYMBOL_GPL(add_timer_on); /** - * __timer_delete - Internal function: Deactivate a timer. + * __timer_delete - Internal function: Deactivate a timer * @timer: The timer to be deactivated + * @shutdown: If true, this indicates that the timer is about to be + * shutdown permanently. + * + * If @shutdown is true then @timer->function is set to NULL under the + * timer base lock which prevents further rearming of the time. In that + * case any attempt to rearm @timer after this function returns will be + * silently ignored. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -static int __timer_delete(struct timer_list *timer) +static int __timer_delete(struct timer_list *timer, bool shutdown) { struct timer_base *base; unsigned long flags; @@ -1312,9 +1319,22 @@ static int __timer_delete(struct timer_l debug_assert_init(timer); - if (timer_pending(timer)) { + /* + * If @shutdown is set then the lock has to be taken whether the + * timer is pending or not to protect against a concurrent rearm + * which might hit between the lockless pending check and the lock + * aquisition. By taking the lock it is ensured that such a newly + * enqueued timer is dequeued and cannot end up with + * timer->function == NULL in the expiry code. + * + * If timer->function is currently executed, then this makes sure + * that the callback cannot requeue the timer. + */ + if (timer_pending(timer) || shutdown) { base = lock_timer_base(timer, &flags); ret = detach_if_pending(timer, base, true); + if (shutdown) + timer->function = NULL; raw_spin_unlock_irqrestore(&base->lock, flags); } @@ -1338,20 +1358,31 @@ EXPORT_SYMBOL(timer_delete); */ int timer_delete(struct timer_list *timer) { - return __timer_delete(timer); + return __timer_delete(timer, false); } EXPORT_SYMBOL(timer_delete); /** * __try_to_del_timer_sync - Internal function: Try to deactivate a timer * @timer: Timer to deactivate + * @shutdown: If true, this indicates that the timer is about to be + * shutdown permanently. + * + * If @shutdown is true then @timer->function is set to NULL under the + * timer base lock which prevents further rearming of the timer. Any + * attempt to rearm @timer after this function returns will be silently + * ignored. + * + * This function cannot guarantee that the timer cannot be rearmed + * right after dropping the base lock if @shutdown is false. That + * needs to be prevented by the calling code if necessary. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated * * %-1 - The timer callback function is running on a different CPU */ -static int __try_to_del_timer_sync(struct timer_list *timer) +static int __try_to_del_timer_sync(struct timer_list *timer, bool shutdown) { struct timer_base *base; unsigned long flags; @@ -1363,6 +1394,8 @@ static int __try_to_del_timer_sync(struc if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); + if (shutdown) + timer->function = NULL; raw_spin_unlock_irqrestore(&base->lock, flags); @@ -1387,7 +1420,7 @@ static int __try_to_del_timer_sync(struc */ int try_to_del_timer_sync(struct timer_list *timer) { - return __try_to_del_timer_sync(timer); + return __try_to_del_timer_sync(timer, false); } EXPORT_SYMBOL(try_to_del_timer_sync); @@ -1468,12 +1501,25 @@ static inline void del_timer_wait_runnin * __timer_delete_sync - Internal function: Deactivate a timer and wait * for the handler to finish. * @timer: The timer to be deactivated + * @shutdown: If true, @timer->function will be set to NULL under the + * timer base lock which prevents rearming of @timer + * + * If @shutdown is not set the timer can be rearmed later. If the timer can + * be rearmed concurrently, i.e. after dropping the base lock then the + * return value is meaningless. + * + * If @shutdown is set then @timer->function is set to NULL under timer + * base lock which prevents rearming of the timer. Any attempt to rearm + * a shutdown timer is silently ignored. + * + * If the timer should be reused after shutdown it has to be initialized + * again. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -static int __timer_delete_sync(struct timer_list *timer) +static int __timer_delete_sync(struct timer_list *timer, bool shutdown) { int ret; @@ -1503,7 +1549,7 @@ static int __timer_delete_sync(struct ti lockdep_assert_preemption_enabled(); do { - ret = __try_to_del_timer_sync(timer); + ret = __try_to_del_timer_sync(timer, shutdown); if (unlikely(ret < 0)) { del_timer_wait_running(timer); @@ -1555,7 +1601,7 @@ static int __timer_delete_sync(struct ti */ int timer_delete_sync(struct timer_list *timer) { - return __timer_delete_sync(timer); + return __timer_delete_sync(timer, false); } EXPORT_SYMBOL(timer_delete_sync); From patchwork Tue Nov 22 17:45:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052624 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81A10C433FE for ; Tue, 22 Nov 2022 17:47:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234554AbiKVRrE (ORCPT ); Tue, 22 Nov 2022 12:47:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233845AbiKVRqE (ORCPT ); Tue, 22 Nov 2022 12:46:04 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08ABA84314; Tue, 22 Nov 2022 09:45:12 -0800 (PST) Message-ID: <20221122173648.962476045@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=WsaxXCiIFZLvl2a+KHGq5BIIa2ad2oCSb0Kkrc+3rTI=; b=QZk3ePmcX54lYpuvD1la8aLDDNqbzt6ROoaV+JUErElnam4yZVY7Gx80SJQzUMOCXIz2Ht sTUqSOD9RkmSIvbEMhh8mA5IYB5hGkCk6PjLUL6H0fGyPYdl/ZfZJXTSXHawgDiMEPVZ1j ie/zZBLnqS7PjUC6hJ78XWcK9Zm67qla9eOD6aBhrBpUAijqU/F9iKSV3wPdSTsAigwbcu rvNOujtqnK+2NiNZRlNwB+cLlDK3AB2SWEoBhTb39UDW0jtd7hMrFDINLhByaWBOIEfBbF 4EIz1Vlu5JztZJ2Ux52LEK0oenA9lzlyzBl5opymWRLLuTZOLBZRR1H8xmAMdw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=WsaxXCiIFZLvl2a+KHGq5BIIa2ad2oCSb0Kkrc+3rTI=; b=UpHhSaR7cw/qvjS025tDoaAw171dk6c6hrHbhMpv01LkMLvO0plj4En4dkHCviNYoGoAui KZXUTLpMfnOGZ+BA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 15/17] timers: Provide timer_shutdown[_sync]() References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:08 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers is not trivial. In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so it to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request. Expose new interfaces for this: timer_shutdown_sync() and timer_shutdown(). timer_shutdown_sync() has the same functionality as timer_delete_sync() plus the NULL-ification of the timer function. timer_shutdown() has the same functionality as timer_delete() plus the NULL-ification of the timer function. In both cases the rearming of the timer is prevented by silently discarding rearm attempts due to timer->function being NULL. Co-developed-by: Steven Rostedt Signed-off-by: Steven Rostedt Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org --- include/linux/timer.h | 2 + kernel/time/timer.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -184,6 +184,8 @@ extern void add_timer(struct timer_list extern int try_to_del_timer_sync(struct timer_list *timer); extern int timer_delete_sync(struct timer_list *timer); extern int timer_delete(struct timer_list *timer); +extern int timer_shutdown_sync(struct timer_list *timer); +extern int timer_shutdown(struct timer_list *timer); /** * del_timer_sync - Delete a pending timer and wait for a running callback --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1363,6 +1363,27 @@ int timer_delete(struct timer_list *time EXPORT_SYMBOL(timer_delete); /** + * timer_shutdown - Deactivate a timer and prevent rearming + * @timer: The timer to be deactivated + * + * The function does not wait for an eventually running timer callback on a + * different CPU but it prevents rearming of the timer. Any attempt to arm + * @timer after this function returns will be silently ignored. + * + * This function is useful for teardown code and should only be used when + * timer_shutdown_sync() cannot be invoked due to locking or context constraints. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending + */ +int timer_shutdown(struct timer_list *timer) +{ + return __timer_delete(timer, true); +} +EXPORT_SYMBOL_GPL(timer_shutdown); + +/** * __try_to_del_timer_sync - Internal function: Try to deactivate a timer * @timer: Timer to deactivate * @shutdown: If true, this indicates that the timer is about to be @@ -1595,6 +1616,9 @@ static int __timer_delete_sync(struct ti * lock. If there is the possibility of a concurrent rearm then the return * value of the function is meaningless. * + * If such a guarantee is needed, e.g. for teardown situations then use + * timer_shutdown_sync() instead. + * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated @@ -1605,6 +1629,48 @@ int timer_delete_sync(struct timer_list } EXPORT_SYMBOL(timer_delete_sync); +/** + * timer_shutdown_sync - Shutdown a timer and prevent rearming + * @timer: The timer to be shutdown + * + * When the function returns it is guaranteed that: + * - @timer is not queued + * - The callback function of @timer is not running + * - @timer cannot be enqueued again. Any attempt to rearm + * @timer is silently ignored. + * + * See timer_delete_sync() for synchronization rules. + * + * This function is useful for final teardown of an infrastructure where + * the timer is subject to a circular dependency problem. + * + * A common pattern for this is a timer and a workqueue where the timer can + * schedule work and work can arm the timer. On shutdown the workqueue must + * be destroyed and the timer must be prevented from rearming. Unless the + * code has conditionals like 'if (mything->in_shutdown)' to prevent that + * there is no way to get this correct with timer_delete_sync(). + * + * timer_shutdown_sync() is solving the problem. The correct ordering of + * calls in this case is: + * + * timer_shutdown_sync(&mything->timer); + * workqueue_destroy(&mything->workqueue); + * + * After this 'mything' can be safely freed. + * + * This obviously requires that the timer is not required to be functional + * for the rest of the shutdown operation. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending + */ +int timer_shutdown_sync(struct timer_list *timer) +{ + return __timer_delete_sync(timer, true); +} +EXPORT_SYMBOL_GPL(timer_shutdown_sync); + static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *), unsigned long baseclk) From patchwork Tue Nov 22 17:45:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052625 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 073C8C4332F for ; Tue, 22 Nov 2022 17:47:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234651AbiKVRrM (ORCPT ); Tue, 22 Nov 2022 12:47:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234570AbiKVRqG (ORCPT ); Tue, 22 Nov 2022 12:46:06 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B18F84331; Tue, 22 Nov 2022 09:45:12 -0800 (PST) Message-ID: <20221122173649.018971915@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139110; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=87QZpCh0faCKJGN7E79B+YLvDwCLrhCyE7zZDe+9ZyU=; b=wtECrHcC+cQJKedJl/ID7HXmlF6xyPU87K1kIEWbWThYdz0SdPyIMyKiTohxMyXNZSN03+ lNqkCwWLR/rNJrh7piFsu58WJuoaS4Klh40CVnY9khH4RfaxRvaylrH3qNJNRIuYslFmQG WzWnDENmC+bBjqzmhuJ2EjyX1ycQ+14FeNBBllrPV9ndwhgQkie3iH2Cn8jB6u2hT9B6tn vT/LV+B8iyUdS97JWLQ6uebM5DtVQVHQdhRSJeX/g6s4adiQmXIwkXIGfUdCi6xrJ+x0Zt 9x4WfDQ1950Vev1ue9cVttlHp44YB2TJrNEbNEPKBzR1PpCda1PPeRQS6+6Nxg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139110; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=87QZpCh0faCKJGN7E79B+YLvDwCLrhCyE7zZDe+9ZyU=; b=jZfQFAaa7z5EeBEPsw/N6W/viHAdTgwJVIkjofEh/cCCE12KwADUYOs2/fkJk2Dvqo3t03 h3cUnBpFVKqYrOAA== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 16/17] timers: Update the documentation to reflect on the new timer_shutdown() API References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:10 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: "Steven Rostedt (Google)" In order to make sure that a timer is not re-armed after it is stopped before freeing, a new shutdown state is added to the timer code. The API timer_shutdown_sync() and timer_shutdown() must be called before the object that holds the timer can be freed. Update the documentation to reflect this new workflow. [ tglx: Updated to the new semantics and updated the zh_CN version ] Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org --- Documentation/RCU/Design/Requirements/Requirements.rst | 2 +- Documentation/core-api/local_ops.rst | 2 +- Documentation/kernel-hacking/locking.rst | 5 +++++ Documentation/translations/zh_CN/core-api/local_ops.rst | 2 +- 4 files changed, 8 insertions(+), 3 deletions(-) --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1858,7 +1858,7 @@ unloaded. After a given module has been one of its functions results in a segmentation fault. The module-unload functions must therefore cancel any delayed calls to loadable-module functions, for example, any outstanding mod_timer() must be dealt -with via timer_delete_sync() or similar. +with via timer_shutdown_sync() or similar. Unfortunately, there is no way to cancel an RCU callback; once you invoke call_rcu(), the callback function is eventually going to be --- a/Documentation/core-api/local_ops.rst +++ b/Documentation/core-api/local_ops.rst @@ -191,7 +191,7 @@ Here is a sample module which implements static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init); --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -1007,6 +1007,11 @@ calling add_timer() at the end of their Because this is a fairly common case which is prone to races, you should use timer_delete_sync() (``include/linux/timer.h``) to handle this case. +Before freeing a timer, timer_shutdown() or timer_shutdown_sync() should be +called which will keep it from being rearmed. Any subsequent attempt to +rearm the timer will be silently ignored by the core code. + + Locking Speed ============= --- a/Documentation/translations/zh_CN/core-api/local_ops.rst +++ b/Documentation/translations/zh_CN/core-api/local_ops.rst @@ -185,7 +185,7 @@ UP之间没有不同的行为，在你� static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init); From patchwork Tue Nov 22 17:45:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13052626 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1DB6C433FE for ; Tue, 22 Nov 2022 17:47:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234583AbiKVRrk (ORCPT ); Tue, 22 Nov 2022 12:47:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234579AbiKVRqH (ORCPT ); Tue, 22 Nov 2022 12:46:07 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7DA2F38; Tue, 22 Nov 2022 09:45:13 -0800 (PST) Message-ID: <20221122173649.075273417@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669139112; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=oI5vClIK5VXyvU77WUUhvfXGhlYe4fvxRaN99XtMgVU=; b=egHu6FhzMGVOkguJ5qXG7yxjl71SA9AN/e6OvsPp9OMLx+nax1Y5Y9fc6fC8+/ZD5Kmsd4 9JgWIHHx91GqueaKBEyztDSGaDLgRJskkRxKdrxIq+GPdZnFz1mlxi/6sscbm0Aye8JRin SOm/Eh6ur6kMYMYDzkA4ioJO9VEFe/om6lMSxytWm+Uw0cuMgcA+EHuVxuX7g7UaJn60er UBWBZbGKIgxWbFwckSJGkUK4fLjYXHi/fZOwnvAh5Ij3tx9F+mAEFycBmDBaDRxPCkxm4s cdIcDm2w3xDCUjTN1z0yy7zYu4kH48kS698M/fW0HGs4l6QLQo5sxiMCk+9A7w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669139112; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=oI5vClIK5VXyvU77WUUhvfXGhlYe4fvxRaN99XtMgVU=; b=KD+ZBXbLsEWmaF1zCfxVndsPLd6sfamM4FuZleyD1L6ZQ9G+52BN/vWvU+sSvxVSiTE2/v VEKFOqrnzE423TBg== From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Steven Rostedt , Anna-Maria Behnsen , Peter Zijlstra , Stephen Boyd , Guenter Roeck , Andrew Morton , Julia Lawall , Arnd Bergmann , Viresh Kumar , Marc Zyngier , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: [patch V2 17/17] Bluetooth: hci_qca: Fix the teardown problem for real References: <20221122171312.191765396@linutronix.de> MIME-Version: 1.0 Date: Tue, 22 Nov 2022 18:45:11 +0100 (CET) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org While discussing solutions for the teardown problem which results from circular dependencies between timers and workqueues, where timers schedule work from their timer callback and workqueues arm the timers from work items, it was discovered that the recent fix to the QCA code is incorrect. That commit fixes the obvious problem of using del_timer() instead of del_timer_sync() and reorders the teardown calls to destroy_workqueue(wq); del_timer_sync(t); This makes it less likely to explode, but it's still broken: destroy_workqueue(wq); /* After this point @wq cannot be touched anymore */ ---> timer expires queue_work(wq) <---- Results in a NULl pointer dereference deep in the work queue core code. del_timer_sync(t); Use the new timer_shutdown_sync() function to ensure that the timers are disarmed, no timer callbacks are running and the timers cannot be armed again. This restores the original teardown sequence: timer_shutdown_sync(t); destroy_workqueue(wq); which is now correct because the timer core silently ignores potential rearming attempts which can happen when destroy_workqueue() drains pending work before mopping up the workqueue. Fixes: 72ef98445aca ("Bluetooth: hci_qca: Use del_timer_sync() before freeing") Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Acked-by: Luiz Augusto von Dentz Cc: Marcel Holtmann Cc: Johan Hedberg Cc: linux-bluetooth@vger.kernel.org Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: netdev@vger.kernel.org Link: https://lore.kernel.org/all/87iljhsftt.ffs@tglx --- drivers/bluetooth/hci_qca.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/bluetooth/hci_qca.c +++ b/drivers/bluetooth/hci_qca.c @@ -696,9 +696,15 @@ static int qca_close(struct hci_uart *hu skb_queue_purge(&qca->tx_wait_q); skb_queue_purge(&qca->txq); skb_queue_purge(&qca->rx_memdump_q); + /* + * Shut the timers down so they can't be rearmed when + * destroy_workqueue() drains pending work which in turn might try + * to arm a timer. After shutdown rearm attempts are silently + * ignored by the timer core code. + */ + timer_shutdown_sync(&qca->tx_idle_timer); + timer_shutdown_sync(&qca->wake_retrans_timer); destroy_workqueue(qca->workqueue); - del_timer_sync(&qca->tx_idle_timer); - del_timer_sync(&qca->wake_retrans_timer); qca->hu = NULL; kfree_skb(qca->rx_skb);