Re: [PATCH v3 1/2] timer: provide an api for deferrable timeout

[Chintan Pandya]

Ping !! Anything open for me to do here ?

On 07/31/2014 01:29 PM, Chintan Pandya wrote:
> 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<cpandya@xxxxxxxxxxxxxx>
> Cc: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
> Cc: John Stultz<john.stultz@xxxxxxxxxx>
> Cc: Peter Zijlstra<peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar<mingo@xxxxxxxxxx>
> Cc: Hugh Dickins<hughd@xxxxxxxxxx>
> ---
> 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

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