From patchwork Mon Dec 30 10:44:37 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 3418881 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 4F373C02DC for ; Mon, 30 Dec 2013 10:45:21 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7601D200E5 for ; Mon, 30 Dec 2013 10:45:16 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 45D3F200DC for ; Mon, 30 Dec 2013 10:45:15 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VxaLO-0001XI-6m; Mon, 30 Dec 2013 10:45:10 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VxaLL-0004Id-Ry; Mon, 30 Dec 2013 10:45:07 +0000 Received: from mail-wg0-f47.google.com ([74.125.82.47]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VxaLF-0004Hc-Lh for linux-arm-kernel@lists.infradead.org; Mon, 30 Dec 2013 10:45:06 +0000 Received: by mail-wg0-f47.google.com with SMTP id n12so9861914wgh.2 for ; Mon, 30 Dec 2013 02:44:40 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=wpIdU4mZ0VOrdI+YZYxcpTDGcmDOECjxaYKbxXDByhM=; b=kfcJZmLIWasSI2+ox8G2nAsq2U1AtzzsF0yeJ5z+mFMXPVvV7kfB6yTwpeYvaK7G2p CyUAU4FUIAHdyrsbjQJseDCcB08HoPLpeDmw8ms5OYHfDpMwdALvPN+Yxlm4WVolrAkq GpUV4MN593gxvsbMVqozxcmwanvUfaGBWBON+rIpIItiv3syPTrp5MsbEBDtuuO0j4HP TGh7VmjuPlWvEykkXEdbC6j4YvVo+aZrHsRgpKA95Zlbh0r+w7CcAXTHCySmPFTrXGw5 EKCuVF+bB9RF3JI1jwQ/HSIWSSyJ8krA7Mf+xZOP6RCbOZG0424k4yctnig4wRiZiOl6 VGZQ== X-Gm-Message-State: ALoCoQnwtj1xQ7o3Q/rHh01Ktz2kHrQwU4jmOZre9EI7fTJhHTJ7j9bKPf2QiU4t37EbVd5iBW39 X-Received: by 10.180.73.173 with SMTP id m13mr35405427wiv.28.1388400280105; Mon, 30 Dec 2013 02:44:40 -0800 (PST) Received: from localhost.localdomain (pur13-1-78-242-214-186.fbx.proxad.net. [78.242.214.186]) by mx.google.com with ESMTPSA id p10sm25457927wje.12.2013.12.30.02.44.38 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 30 Dec 2013 02:44:39 -0800 (PST) From: Daniel Lezcano To: mingo@kernel.org, tglx@linutronix.de Subject: [PATCH] clocksource: cadence_ttc: Fix mutex taken inside interrupt context Date: Mon, 30 Dec 2013 11:44:37 +0100 Message-Id: <1388400277-13038-1-git-send-email-daniel.lezcano@linaro.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <52C14E45.5040403@linaro.org> References: <52C14E45.5040403@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131230_054501_922304_7183E1E3 X-CRM114-Status: GOOD ( 15.64 ) X-Spam-Score: -2.6 (--) Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, soren.brinkmann@xilinx.com X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Soren Brinkmann When the kernel is compiled with: CONFIG_HIGH_RES_TIMERS=no CONFIG_HZ_PERIODIC=yes CONFIG_DEBUG_ATOMIC_SLEEP=yes The following WARN appears: WARNING: CPU: 1 PID: 0 at linux/kernel/mutex.c:856 mutex_trylock+0x70/0x1fc() DEBUG_LOCKS_WARN_ON(in_interrupt()) Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.12.0-xilinx-dirty #93 [] (unwind_backtrace+0x0/0x11c) from [] (show_stack+0x10/0x14) [] (show_stack+0x10/0x14) from [] (dump_stack+0x7c/0xc0) [] (dump_stack+0x7c/0xc0) from [] (warn_slowpath_common+0x60/0x84) [] (warn_slowpath_common+0x60/0x84) from [] (warn_slowpath_fmt+0x2c/0x3c) [] (warn_slowpath_fmt+0x2c/0x3c) from [] (mutex_trylock+0x70/0x1fc) [] (mutex_trylock+0x70/0x1fc) from [] (clk_prepare_lock+0xc/0xe4) [] (clk_prepare_lock+0xc/0xe4) from [] (clk_get_rate+0xc/0x44) [] (clk_get_rate+0xc/0x44) from [] (ttc_set_mode+0x34/0x78) [] (ttc_set_mode+0x34/0x78) from [] (clockevents_set_mode+0x28/0x5c) [] (clockevents_set_mode+0x28/0x5c) from [] (tick_broadcast_on_off+0x190/0x1c0) [] (tick_broadcast_on_off+0x190/0x1c0) from [] (clockevents_notify+0x58/0x1ac) [] (clockevents_notify+0x58/0x1ac) from [] (cpuidle_setup_broadcast_timer+0x20/0x24) [] (cpuidle_setup_broadcast_timer+0x20/0x24) from [] (generic_smp_call_function_single_interrupt+0) [] (generic_smp_call_function_single_interrupt+0xe0/0x130) from [] (handle_IPI+0x88/0x118) [] (handle_IPI+0x88/0x118) from [] (gic_handle_irq+0x58/0x60) [] (gic_handle_irq+0x58/0x60) from [] (__irq_svc+0x44/0x78) Exception stack(0xef099fa0 to 0xef099fe8) 9fa0: 00000001 ef092100 00000000 ef092100 ef098000 00000015 c0399f2c c0579d74 9fc0: 0000406a 413fc090 00000000 00000000 00000000 ef099fe8 c00666ec c000f46c 9fe0: 20000113 ffffffff [] (__irq_svc+0x44/0x78) from [] (arch_cpu_idle+0x34/0x3c) [] (arch_cpu_idle+0x34/0x3c) from [] (cpu_startup_entry+0xa8/0x10c) [] (cpu_startup_entry+0xa8/0x10c) from [<000085a4>] (0x85a4) We are in an interrupt context (IPI) and we are calling clk_get_rate in the set_mode function which in turn ends up by getting a mutex... Even if that does not hang, it is a potential kernel deadlock. It is not allowed to call clk_get_rate() from interrupt context. To avoid such calls the timer input frequency is stored in the driver's data struct which makes it accessible to the driver in any context. [dlezcano] completed the changelog with the WARN trace and added a more detailed description. Tested on zync zc702. Acked-by: Daniel Lezcano Tested-by: Daniel Lezcano Signed-off-by: Soren Brinkmann Signed-off-by: Daniel Lezcano --- drivers/clocksource/cadence_ttc_timer.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c index b2bb3a4b..a92350b 100644 --- a/drivers/clocksource/cadence_ttc_timer.c +++ b/drivers/clocksource/cadence_ttc_timer.c @@ -67,11 +67,13 @@ * struct ttc_timer - This definition defines local timer structure * * @base_addr: Base address of timer + * @freq: Timer input clock frequency * @clk: Associated clock source * @clk_rate_change_nb Notifier block for clock rate changes */ struct ttc_timer { void __iomem *base_addr; + unsigned long freq; struct clk *clk; struct notifier_block clk_rate_change_nb; }; @@ -196,9 +198,8 @@ static void ttc_set_mode(enum clock_event_mode mode, switch (mode) { case CLOCK_EVT_MODE_PERIODIC: - ttc_set_interval(timer, - DIV_ROUND_CLOSEST(clk_get_rate(ttce->ttc.clk), - PRESCALE * HZ)); + ttc_set_interval(timer, DIV_ROUND_CLOSEST(ttce->ttc.freq, + PRESCALE * HZ)); break; case CLOCK_EVT_MODE_ONESHOT: case CLOCK_EVT_MODE_UNUSED: @@ -273,6 +274,8 @@ static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base) return; } + ttccs->ttc.freq = clk_get_rate(ttccs->ttc.clk); + ttccs->ttc.clk_rate_change_nb.notifier_call = ttc_rate_change_clocksource_cb; ttccs->ttc.clk_rate_change_nb.next = NULL; @@ -298,16 +301,14 @@ static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base) __raw_writel(CNT_CNTRL_RESET, ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET); - err = clocksource_register_hz(&ttccs->cs, - clk_get_rate(ttccs->ttc.clk) / PRESCALE); + err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE); if (WARN_ON(err)) { kfree(ttccs); return; } ttc_sched_clock_val_reg = base + TTC_COUNT_VAL_OFFSET; - setup_sched_clock(ttc_sched_clock_read, 16, - clk_get_rate(ttccs->ttc.clk) / PRESCALE); + setup_sched_clock(ttc_sched_clock_read, 16, ttccs->ttc.freq / PRESCALE); } static int ttc_rate_change_clockevent_cb(struct notifier_block *nb, @@ -334,6 +335,9 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb, ndata->new_rate / PRESCALE); local_irq_restore(flags); + /* update cached frequency */ + ttc->freq = ndata->new_rate; + /* fall through */ } case PRE_RATE_CHANGE: @@ -367,6 +371,7 @@ static void __init ttc_setup_clockevent(struct clk *clk, if (clk_notifier_register(ttcce->ttc.clk, &ttcce->ttc.clk_rate_change_nb)) pr_warn("Unable to register clock notifier.\n"); + ttcce->ttc.freq = clk_get_rate(ttcce->ttc.clk); ttcce->ttc.base_addr = base; ttcce->ce.name = "ttc_clockevent"; @@ -396,7 +401,7 @@ static void __init ttc_setup_clockevent(struct clk *clk, } clockevents_config_and_register(&ttcce->ce, - clk_get_rate(ttcce->ttc.clk) / PRESCALE, 1, 0xfffe); + ttcce->ttc.freq / PRESCALE, 1, 0xfffe); } /**