From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anand Moon Subject: [PATCH] pwm: Avoid double mutex lock on pwm_enable Date: Fri, 20 Nov 2015 16:59:00 +0000 Message-ID: <1448038740-2811-1-git-send-email-linux.amoon@gmail.com> Return-path: Sender: linux-samsung-soc-owner@vger.kernel.org To: Guenter Roeck , Thierry Reding , Krzysztof Kozlowski , Javier Martinez Canillas , Anand Moon Cc: linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org List-Id: linux-pwm@vger.kernel.org Commit d1cd21427747f15920cd726f5f67a07880e7dee4 (pwm: Set enable state properly on failed call to enable) introduce double lock of mutex on pwm_enable Changes fix the following debug lock warning. [ 2.701720] WARNING: CPU: 3 PID: 0 at kernel/locking/mutex.c:526 __mutex_lock_slowpath+0x3bc/0x404() [ 2.701731] DEBUG_LOCKS_WARN_ON(in_interrupt()) [ 2.701737] Modules linked in: [ 2.701748] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0-rc1-xu4f #24 [ 2.701753] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [ 2.701787] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 2.701808] [] (show_stack) from [] (dump_stack+0x84/0xc4) [ 2.701824] [] (dump_stack) from [] (warn_slowpath_common+0x80/0xb0) [ 2.701836] [] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x30/0x40) [ 2.701849] [] (warn_slowpath_fmt) from [] (__mutex_lock_slowpath+0x3bc/0x404) [ 2.701864] [] (__mutex_lock_slowpath) from [] (mutex_lock+0xc/0x24) [ 2.701884] [] (mutex_lock) from [] (pwm_enable+0x20/0x7c) [ 2.701903] [] (pwm_enable) from [] (led_heartbeat_function+0x74/0x144) [ 2.701919] [] (led_heartbeat_function) from [] (call_timer_fn+0x24/0x98) [ 2.701932] [] (call_timer_fn) from [] (run_timer_softirq+0x160/0x21c) [ 2.701946] [] (run_timer_softirq) from [] (__do_softirq+0x110/0x228) [ 2.701959] [] (__do_softirq) from [] (irq_exit+0xc0/0xfc) [ 2.701976] [] (irq_exit) from [] (__handle_domain_irq+0x80/0xec) [ 2.701990] [] (__handle_domain_irq) from [] (gic_handle_irq+0x54/0x94) [ 2.702001] [] (gic_handle_irq) from [] (__irq_svc+0x54/0x90) [ 2.702008] Exception stack(0xee8bdf88 to 0xee8bdfd0) [ 2.702019] df80: 00000001 00000000 00000000 c001b720 ee8bc000 c0573354 [ 2.702031] dfa0: 00000000 00000000 ee8bdfe0 c07f92e4 c08004b4 c08004bc f0806640 ee8bdfd8 [ 2.702039] dfc0: c0010180 c0010184 60000013 ffffffff [ 2.702053] [] (__irq_svc) from [] (arch_cpu_idle+0x38/0x3c) [ 2.702073] [] (arch_cpu_idle) from [] (cpu_startup_entry+0x1ec/0x270) [ 2.702086] [] (cpu_startup_entry) from [<4000956c>] (0x4000956c) [ 2.702093] ---[ end trace 539af70491f4f1a9 ]--- Signed-off-by: Anand Moon --- drivers/pwm/core.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index d24ca5f..b8f035a 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -506,16 +506,12 @@ int pwm_enable(struct pwm_device *pwm) if (!pwm) return -EINVAL; - mutex_lock(&pwm->lock); - if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) { err = pwm->chip->ops->enable(pwm->chip, pwm); if (err) clear_bit(PWMF_ENABLED, &pwm->flags); } - mutex_unlock(&pwm->lock); - return err; } EXPORT_SYMBOL_GPL(pwm_enable); -- 2.1.4