Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756259AbaGaIAh (ORCPT ); Thu, 31 Jul 2014 04:00:37 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:45349 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755824AbaGaIAg (ORCPT ); Thu, 31 Jul 2014 04:00:36 -0400 From: Chintan Pandya To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Chintan Pandya , Thomas Gleixner , John Stultz , Peter Zijlstra , Ingo Molnar , Hugh Dickins Subject: [PATCH v3 1/2] timer: provide an api for deferrable timeout Date: Thu, 31 Jul 2014 13:29:50 +0530 Message-Id: <1406793591-26793-2-git-send-email-cpandya@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org schedule_timeout wakes up the CPU from IDLE state. For some use cases it is not desirable, hence introduce a convenient API (schedule_timeout_deferrable_interruptible) on similar pattern which uses a deferrable timer. Signed-off-by: Chintan Pandya Cc: Thomas Gleixner Cc: John Stultz Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Hugh Dickins --- Changes: V2-->V3: - Big comment moved from static function to exported function - Using __setup_timer_on_stack for better readability V2: - this patch has been newly introduced in patch v2 include/linux/sched.h | 2 ++ kernel/time/timer.c | 73 +++++++++++++++++++++++++++++++-------------------- 2 files changed, 47 insertions(+), 28 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 89f531e..10b154e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -377,6 +377,8 @@ extern int in_sched_functions(unsigned long addr); #define MAX_SCHEDULE_TIMEOUT LONG_MAX extern signed long schedule_timeout(signed long timeout); extern signed long schedule_timeout_interruptible(signed long timeout); +extern signed long +schedule_timeout_deferrable_interruptible(signed long timeout); extern signed long schedule_timeout_killable(signed long timeout); extern signed long schedule_timeout_uninterruptible(signed long timeout); asmlinkage void schedule(void); diff --git a/kernel/time/timer.c b/kernel/time/timer.c index aca5dfe..f4c4082 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1431,33 +1431,8 @@ static void process_timeout(unsigned long __data) wake_up_process((struct task_struct *)__data); } -/** - * schedule_timeout - sleep until timeout - * @timeout: timeout value in jiffies - * - * Make the current task sleep until @timeout jiffies have - * elapsed. The routine will return immediately unless - * the current task state has been set (see set_current_state()). - * - * You can set the task state as follows - - * - * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to - * pass before the routine returns. The routine will return 0 - * - * %TASK_INTERRUPTIBLE - the routine may return early if a signal is - * delivered to the current task. In this case the remaining time - * in jiffies will be returned, or 0 if the timer expired in time - * - * The current task state is guaranteed to be TASK_RUNNING when this - * routine returns. - * - * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule - * the CPU away without a bound on the timeout. In this case the return - * value will be %MAX_SCHEDULE_TIMEOUT. - * - * In all cases the return value is guaranteed to be non-negative. - */ -signed long __sched schedule_timeout(signed long timeout) +static signed long +__sched __schedule_timeout(signed long timeout, unsigned long flag) { struct timer_list timer; unsigned long expire; @@ -1493,7 +1468,9 @@ signed long __sched schedule_timeout(signed long timeout) expire = timeout + jiffies; - setup_timer_on_stack(&timer, process_timeout, (unsigned long)current); + __setup_timer_on_stack(&timer, process_timeout, (unsigned long)current, + flag); + __mod_timer(&timer, expire, false, TIMER_NOT_PINNED); schedule(); del_singleshot_timer_sync(&timer); @@ -1506,12 +1483,52 @@ signed long __sched schedule_timeout(signed long timeout) out: return timeout < 0 ? 0 : timeout; } + +/** + * schedule_timeout - sleep until timeout + * @timeout: timeout value in jiffies + * + * Make the current task sleep until @timeout jiffies have + * elapsed. The routine will return immediately unless + * the current task state has been set (see set_current_state()). + * + * You can set the task state as follows - + * + * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to + * pass before the routine returns. The routine will return 0 + * + * %TASK_INTERRUPTIBLE - the routine may return early if a signal is + * delivered to the current task. In this case the remaining time + * in jiffies will be returned, or 0 if the timer expired in time + * + * The current task state is guaranteed to be TASK_RUNNING when this + * routine returns. + * + * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule + * the CPU away without a bound on the timeout. In this case the return + * value will be %MAX_SCHEDULE_TIMEOUT. + * + * In all cases the return value is guaranteed to be non-negative. + */ +signed long __sched schedule_timeout(signed long timeout) +{ + return __schedule_timeout(timeout, 0); +} EXPORT_SYMBOL(schedule_timeout); /* * We can use __set_current_state() here because schedule_timeout() calls * schedule() unconditionally. */ + +signed long +__sched schedule_timeout_deferrable_interruptible(signed long timeout) +{ + __set_current_state(TASK_INTERRUPTIBLE); + return __schedule_timeout(timeout, TIMER_DEFERRABLE); +} +EXPORT_SYMBOL(schedule_timeout_deferrable_interruptible); + signed long __sched schedule_timeout_interruptible(signed long timeout) { __set_current_state(TASK_INTERRUPTIBLE); -- Chintan Pandya QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/