2008-08-05 15:29:24

by Oleg Nesterov

Subject: [PATCH 2/2] posix-timers: lock_timer: make it readable

Cleanup. Imho makes the code much more understandable. At least this
patch lessens both the source and compiled code.

Signed-off-by: Oleg Nesterov <[email protected]>

--- 26-rc2/kernel/posix-timers.c~10_LOCK_TIMER 2008-08-05 17:56:33.000000000 +0400
+++ 26-rc2/kernel/posix-timers.c 2008-08-05 18:53:19.000000000 +0400
@@ -557,7 +557,7 @@ out:
* the find to the timer lock. To avoid a dead lock, the timer id MUST
* be release with out holding the timer lock.
*/
-static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
+static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
{
struct k_itimer *timr;
/*
@@ -565,23 +565,20 @@ static struct k_itimer * lock_timer(time
* flags part over to the timer lock. Must not let interrupts in
* while we are moving the lock.
*/
-
spin_lock_irqsave(&idr_lock, *flags);
- timr = idr_find(&posix_timers_id, (int) timer_id);
+ timr = idr_find(&posix_timers_id, (int)timer_id);
if (timr) {
spin_lock(&timr->it_lock);
-
- if (!timr->it_process ||
- !same_thread_group(timr->it_process, current)) {
- spin_unlock(&timr->it_lock);
- spin_unlock_irqrestore(&idr_lock, *flags);
- timr = NULL;
- } else
+ if (timr->it_process &&
+ same_thread_group(timr->it_process, current)) {
spin_unlock(&idr_lock);
- } else
- spin_unlock_irqrestore(&idr_lock, *flags);
+ return timr;
+ }
+ spin_unlock(&timr->it_lock);
+ }
+ spin_unlock_irqrestore(&idr_lock, *flags);

- return timr;
+ return NULL;
}

/*

2008-08-05 15:36:49

by Oleg Nesterov

Subject: Re: [PATCH 2/2] posix-timers: lock_timer: make it readable

On 08/05, Oleg Nesterov wrote:
>
> Cleanup. Imho makes the code much more understandable. At least this
> patch lessens both the source and compiled code.

To simplify the review, I am posting the code with this patch applied.

static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
{
struct k_itimer *timr;
/*
* Watch out here. We do a irqsave on the idr_lock and pass the
* flags part over to the timer lock. Must not let interrupts in
* while we are moving the lock.
*/
spin_lock_irqsave(&idr_lock, *flags);
timr = idr_find(&posix_timers_id, (int)timer_id);
if (timr) {
spin_lock(&timr->it_lock);
if (timr->it_process &&
same_thread_group(timr->it_process, current)) {
spin_unlock(&idr_lock);
return timr;
}
spin_unlock(&timr->it_lock);
}
spin_unlock_irqrestore(&idr_lock, *flags);

return NULL;
}

Oleg.