From patchwork Thu Mar 7 15:58:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabien DESSENNE X-Patchwork-Id: 10843297 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D553317E9 for ; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BBAF32B0B0 for ; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B88962AD0D; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 480942A76D for ; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726166AbfCGP6s (ORCPT ); Thu, 7 Mar 2019 10:58:48 -0500 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:5471 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726249AbfCGP6s (ORCPT ); Thu, 7 Mar 2019 10:58:48 -0500 Received: from pps.filterd (m0046037.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x27FkSNF025831; Thu, 7 Mar 2019 16:58:42 +0100 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 2r315usxvn-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Thu, 07 Mar 2019 16:58:42 +0100 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id D1C4B31; Thu, 7 Mar 2019 15:58:40 +0000 (GMT) Received: from Webmail-eu.st.com (Safex1hubcas24.st.com [10.75.90.94]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id B4345531C; Thu, 7 Mar 2019 15:58:40 +0000 (GMT) Received: from SAFEX1HUBCAS23.st.com (10.75.90.47) by Safex1hubcas24.st.com (10.75.90.94) with Microsoft SMTP Server (TLS) id 14.3.361.1; Thu, 7 Mar 2019 16:58:40 +0100 Received: from localhost (10.129.4.33) by webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.361.1; Thu, 7 Mar 2019 16:58:40 +0100 From: Fabien Dessenne To: Ohad Ben-Cohen , Bjorn Andersson , Jonathan Corbet , , , CC: Fabien Dessenne , Benjamin Gaignard , Alexandre Torgue Subject: [PATCH 1/2] hwspinlock: document the hwspinlock 'raw' API Date: Thu, 7 Mar 2019 16:58:22 +0100 Message-ID: <1551974303-24542-2-git-send-email-fabien.dessenne@st.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551974303-24542-1-git-send-email-fabien.dessenne@st.com> References: <1551974303-24542-1-git-send-email-fabien.dessenne@st.com> MIME-Version: 1.0 X-Originating-IP: [10.129.4.33] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-07_08:,, signatures=0 Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Document the hwspin_lock_timeout_raw(), hwspin_trylock_raw() and hwspin_unlock_raw() API. Signed-off-by: Fabien Dessenne --- Documentation/hwspinlock.txt | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt index ed640a2..c3403f9 100644 --- a/Documentation/hwspinlock.txt +++ b/Documentation/hwspinlock.txt @@ -136,6 +136,23 @@ The function will never sleep. :: + int hwspin_lock_timeout_raw(struct hwspinlock *hwlock, unsigned int timeout); + +Lock a previously-assigned hwspinlock with a timeout limit (specified in +msecs). If the hwspinlock is already taken, the function will busy loop +waiting for it to be released, but give up when the timeout elapses. + +Caution: User must protect the routine of getting hardware lock with mutex +or spinlock to avoid dead-lock, that will let user can do some time-consuming +or sleepable operations under the hardware lock. + +Returns 0 when successful and an appropriate error code otherwise (most +notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs). + +The function will never sleep. + +:: + int hwspin_trylock(struct hwspinlock *hwlock); @@ -186,6 +203,21 @@ The function will never sleep. :: + int hwspin_trylock_raw(struct hwspinlock *hwlock); + +Attempt to lock a previously-assigned hwspinlock, but immediately fail if +it is already taken. + +Caution: User must protect the routine of getting hardware lock with mutex +or spinlock to avoid dead-lock, that will let user can do some time-consuming +or sleepable operations under the hardware lock. + +Returns 0 on success and an appropriate error code otherwise (most +notably -EBUSY if the hwspinlock was already taken). +The function will never sleep. + +:: + void hwspin_unlock(struct hwspinlock *hwlock); Unlock a previously-locked hwspinlock. Always succeed, and can be called @@ -222,6 +254,16 @@ the given flags. This function will never sleep. :: + void hwspin_unlock_raw(struct hwspinlock *hwlock); + +Unlock a previously-locked hwspinlock. + +The caller should **never** unlock an hwspinlock which is already unlocked. +Doing so is considered a bug (there is no protection against this). +This function will never sleep. + +:: + int hwspin_lock_get_id(struct hwspinlock *hwlock); Retrieve id number of a given hwspinlock. This is needed when an From patchwork Thu Mar 7 15:58:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabien DESSENNE X-Patchwork-Id: 10843295 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8EDEA1575 for ; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 746312ACDC for ; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 59E9A2A9F4; Thu, 7 Mar 2019 15:59:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 382F92E23B for ; Thu, 7 Mar 2019 15:59:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726393AbfCGP6v (ORCPT ); Thu, 7 Mar 2019 10:58:51 -0500 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:34183 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbfCGP6s (ORCPT ); Thu, 7 Mar 2019 10:58:48 -0500 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x27FkcsM001047; Thu, 7 Mar 2019 16:58:42 +0100 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 2r2ng25n7s-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Thu, 07 Mar 2019 16:58:42 +0100 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 00FCB3A; Thu, 7 Mar 2019 15:58:41 +0000 (GMT) Received: from Webmail-eu.st.com (Safex1hubcas22.st.com [10.75.90.92]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id C8C465323; Thu, 7 Mar 2019 15:58:41 +0000 (GMT) Received: from SAFEX1HUBCAS23.st.com (10.75.90.47) by Safex1hubcas22.st.com (10.75.90.92) with Microsoft SMTP Server (TLS) id 14.3.361.1; Thu, 7 Mar 2019 16:58:41 +0100 Received: from localhost (10.129.4.33) by webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.361.1; Thu, 7 Mar 2019 16:58:41 +0100 From: Fabien Dessenne To: Ohad Ben-Cohen , Bjorn Andersson , Jonathan Corbet , , , CC: Fabien Dessenne , Benjamin Gaignard , Alexandre Torgue Subject: [PATCH 2/2] hwspinlock: add the 'in_atomic' API Date: Thu, 7 Mar 2019 16:58:23 +0100 Message-ID: <1551974303-24542-3-git-send-email-fabien.dessenne@st.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551974303-24542-1-git-send-email-fabien.dessenne@st.com> References: <1551974303-24542-1-git-send-email-fabien.dessenne@st.com> MIME-Version: 1.0 X-Originating-IP: [10.129.4.33] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-07_08:,, signatures=0 Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add the 'in_atomic' mode which can be called from an atomic context. This mode relies on the existing 'raw' mode (no lock, no preemption/irq disabling) with the difference that the timeout is not based on jiffies (jiffies won't increase when irq are disabled) but handled with busy-waiting udelay() calls. Signed-off-by: Fabien Dessenne --- Documentation/hwspinlock.txt | 39 +++++++++++++++++++++++ drivers/hwspinlock/hwspinlock_core.c | 43 +++++++++++++++++-------- include/linux/hwspinlock.h | 61 ++++++++++++++++++++++++++++++++++-- 3 files changed, 127 insertions(+), 16 deletions(-) diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt index c3403f9..6f03713 100644 --- a/Documentation/hwspinlock.txt +++ b/Documentation/hwspinlock.txt @@ -153,6 +153,22 @@ The function will never sleep. :: + int hwspin_lock_timeout_in_atomic(struct hwspinlock *hwlock, unsigned int to); + +Lock a previously-assigned hwspinlock with a timeout limit (specified in +msecs). If the hwspinlock is already taken, the function will busy loop +waiting for it to be released, but give up when the timeout elapses. + +This function shall be called only from an atomic context and the timeout +value shall not exceed a few msecs. + +Returns 0 when successful and an appropriate error code otherwise (most +notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs). + +The function will never sleep. + +:: + int hwspin_trylock(struct hwspinlock *hwlock); @@ -218,6 +234,19 @@ The function will never sleep. :: + int hwspin_trylock_in_atomic(struct hwspinlock *hwlock); + +Attempt to lock a previously-assigned hwspinlock, but immediately fail if +it is already taken. + +This function shall be called only from an atomic context. + +Returns 0 on success and an appropriate error code otherwise (most +notably -EBUSY if the hwspinlock was already taken). +The function will never sleep. + +:: + void hwspin_unlock(struct hwspinlock *hwlock); Unlock a previously-locked hwspinlock. Always succeed, and can be called @@ -264,6 +293,16 @@ This function will never sleep. :: + void hwspin_unlock_in_atomic(struct hwspinlock *hwlock); + +Unlock a previously-locked hwspinlock. + +The caller should **never** unlock an hwspinlock which is already unlocked. +Doing so is considered a bug (there is no protection against this). +This function will never sleep. + +:: + int hwspin_lock_get_id(struct hwspinlock *hwlock); Retrieve id number of a given hwspinlock. This is needed when an diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c index 2bad40d..1d61fad 100644 --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -9,6 +9,7 @@ #define pr_fmt(fmt) "%s: " fmt, __func__ +#include #include #include #include @@ -23,6 +24,9 @@ #include "hwspinlock_internal.h" +/* retry delay used in atomic context */ +#define HWSPINLOCK_RETRY_DELAY_US 100 + /* radix tree tags */ #define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */ @@ -68,11 +72,11 @@ static DEFINE_MUTEX(hwspinlock_tree_lock); * user need some time-consuming or sleepable operations under the hardware * lock, they need one sleepable lock (like mutex) to protect the operations. * - * If the mode is not HWLOCK_RAW, upon a successful return from this function, - * preemption (and possibly interrupts) is disabled, so the caller must not - * sleep, and is advised to release the hwspinlock as soon as possible. This is - * required in order to minimize remote cores polling on the hardware - * interconnect. + * If the mode is neither HWLOCK_IN_ATOMIC nor HWLOCK_RAW, upon a successful + * return from this function, preemption (and possibly interrupts) is disabled, + * so the caller must not sleep, and is advised to release the hwspinlock as + * soon as possible. This is required in order to minimize remote cores polling + * on the hardware interconnect. * * The user decides whether local interrupts are disabled or not, and if yes, * whether he wants their previous state to be saved. It is up to the user @@ -112,6 +116,7 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) ret = spin_trylock_irq(&hwlock->lock); break; case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: ret = 1; break; default: @@ -136,6 +141,7 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) spin_unlock_irq(&hwlock->lock); break; case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: /* Nothing to do */ break; default: @@ -179,11 +185,14 @@ EXPORT_SYMBOL_GPL(__hwspin_trylock); * user need some time-consuming or sleepable operations under the hardware * lock, they need one sleepable lock (like mutex) to protect the operations. * - * If the mode is not HWLOCK_RAW, upon a successful return from this function, - * preemption is disabled (and possibly local interrupts, too), so the caller - * must not sleep, and is advised to release the hwspinlock as soon as possible. - * This is required in order to minimize remote cores polling on the - * hardware interconnect. + * If the mode is HWLOCK_IN_ATOMIC (called from an atomic context) the timeout + * is handled with busy-waiting delays, hence shall not exceed few msecs. + * + * If the mode is neither HWLOCK_IN_ATOMIC nor HWLOCK_RAW, upon a successful + * return from this function, preemption (and possibly interrupts) is disabled, + * so the caller must not sleep, and is advised to release the hwspinlock as + * soon as possible. This is required in order to minimize remote cores polling + * on the hardware interconnect. * * The user decides whether local interrupts are disabled or not, and if yes, * whether he wants their previous state to be saved. It is up to the user @@ -198,7 +207,7 @@ int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to, int mode, unsigned long *flags) { int ret; - unsigned long expire; + unsigned long expire, atomic_delay = 0; expire = msecs_to_jiffies(to) + jiffies; @@ -212,8 +221,15 @@ int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to, * The lock is already taken, let's check if the user wants * us to try again */ - if (time_is_before_eq_jiffies(expire)) - return -ETIMEDOUT; + if (mode == HWLOCK_IN_ATOMIC) { + udelay(HWSPINLOCK_RETRY_DELAY_US); + atomic_delay += HWSPINLOCK_RETRY_DELAY_US; + if (atomic_delay > to * 1000) + return -ETIMEDOUT; + } else { + if (time_is_before_eq_jiffies(expire)) + return -ETIMEDOUT; + } /* * Allow platform-specific relax handlers to prevent @@ -276,6 +292,7 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) spin_unlock_irq(&hwlock->lock); break; case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: /* Nothing to do */ break; default: diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h index 0afe693..bfe7c1f 100644 --- a/include/linux/hwspinlock.h +++ b/include/linux/hwspinlock.h @@ -14,9 +14,10 @@ #include /* hwspinlock mode argument */ -#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */ -#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */ -#define HWLOCK_RAW 0x03 +#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */ +#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */ +#define HWLOCK_RAW 0x03 +#define HWLOCK_IN_ATOMIC 0x04 /* Called while in atomic context */ struct device; struct device_node; @@ -223,6 +224,23 @@ static inline int hwspin_trylock_raw(struct hwspinlock *hwlock) } /** + * hwspin_trylock_in_atomic() - attempt to lock a specific hwspinlock + * @hwlock: an hwspinlock which we want to trylock + * + * This function attempts to lock an hwspinlock, and will immediately fail + * if the hwspinlock is already taken. + * + * This function shall be called only from an atomic context. + * + * Returns 0 if we successfully locked the hwspinlock, -EBUSY if + * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid. + */ +static inline int hwspin_trylock_in_atomic(struct hwspinlock *hwlock) +{ + return __hwspin_trylock(hwlock, HWLOCK_IN_ATOMIC, NULL); +} + +/** * hwspin_trylock() - attempt to lock a specific hwspinlock * @hwlock: an hwspinlock which we want to trylock * @@ -313,6 +331,28 @@ int hwspin_lock_timeout_raw(struct hwspinlock *hwlock, unsigned int to) } /** + * hwspin_lock_timeout_in_atomic() - lock an hwspinlock with timeout limit + * @hwlock: the hwspinlock to be locked + * @to: timeout value in msecs + * + * This function locks the underlying @hwlock. If the @hwlock + * is already taken, the function will busy loop waiting for it to + * be released, but give up when @timeout msecs have elapsed. + * + * This function shall be called only from an atomic context and the timeout + * value shall not exceed a few msecs. + * + * Returns 0 when the @hwlock was successfully taken, and an appropriate + * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still + * busy after @timeout msecs). The function will never sleep. + */ +static inline +int hwspin_lock_timeout_in_atomic(struct hwspinlock *hwlock, unsigned int to) +{ + return __hwspin_lock_timeout(hwlock, to, HWLOCK_IN_ATOMIC, NULL); +} + +/** * hwspin_lock_timeout() - lock an hwspinlock with timeout limit * @hwlock: the hwspinlock to be locked * @to: timeout value in msecs @@ -387,6 +427,21 @@ static inline void hwspin_unlock_raw(struct hwspinlock *hwlock) } /** + * hwspin_unlock_in_atomic() - unlock hwspinlock + * @hwlock: a previously-acquired hwspinlock which we want to unlock + * + * This function will unlock a specific hwspinlock. + * + * @hwlock must be already locked (e.g. by hwspin_trylock()) before calling + * this function: it is a bug to call unlock on a @hwlock that is already + * unlocked. + */ +static inline void hwspin_unlock_in_atomic(struct hwspinlock *hwlock) +{ + __hwspin_unlock(hwlock, HWLOCK_IN_ATOMIC, NULL); +} + +/** * hwspin_unlock() - unlock hwspinlock * @hwlock: a previously-acquired hwspinlock which we want to unlock *