Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Fri, 7 Jun 2013 15:07:23 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] wait: introduce prepare_to_wait_event() |
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Hi Tejun,
On 06/06, Tejun Heo wrote: > > Which tree are the patches based on? I'm getting conflicts on > linus#master, mmotd and next.
Hmm. linus#master. I just verified that the patches apply cleanly after git-pull.
> Reviewed-by: Tejun Heo <tj@kernel.org>
Thanks,
> But a couple nits. > > > +int > > I don't think we need to keep the unnecessary line break here. All > other functions in the file don't do it except for the two > prepare_to_wait functions. No need to give the weirdos more power. :)
Yes, I tried to follow the style around the new helper, but the extra line is not needed.
Please see v2 below, no other changes.
> > +prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state) > > +{ > > + if (signal_pending_state(state, current)) > > + return -ERESTARTSYS; > > + > > + wait->private = current; > > + wait->func = autoremove_wake_function; > > + prepare_to_wait(q, wait, state); > > I wonder whether it'd be worthwhile to make prepare_to_wait() inline > so that it can be inlined into the above. I think gcc is smart enough > to emit inline for in-file stuff and then build a proper function for > external references. No biggie. Just wondering.
Not sure... As you can see from this patch, I like -Os more than -O2 ;)
------------------------------------------------------------------------------ Subject: [PATCH v2 2/2] wait: introduce prepare_to_wait_event()
Add the new helper, prepare_to_wait_event() which should only be used by wait_event_common/etc.
prepare_to_wait_event() returns -ERESTARTSYS if signal_pending_state() is true, otherwise it calls prepare_to_wait(). This allows to uninline the signal-pending checks in wait_event_*.
Also, it can initialize wait->private/func. We do not care they were already initialized, the values are the same. This also shaves a couple of insns from the inlined code.
Unlike the previous change, this patch "reliably" shrinks the size of generated code for every wait_event*() call.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Tejun Heo <tj@kernel.org> --- include/linux/wait.h | 22 +++++++++++----------- kernel/wait.c | 13 +++++++++++++ 2 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h index 392c54d..a2314dd 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -176,28 +176,27 @@ wait_queue_head_t *bit_waitqueue(void *, int); #define __wait_no_timeout(tout) \ (__builtin_constant_p(tout) && (tout) == MAX_SCHEDULE_TIMEOUT) -/* uglified signal_pending_state() optimized for constant state */ -#define __wait_signal_pending(state) \ - ((state == TASK_INTERRUPTIBLE) ? signal_pending(current) : \ - (state == TASK_KILLABLE) ? fatal_signal_pending(current) : \ - 0) +#define __wait_interruptible(state) \ + (!__builtin_constant_p(state) || \ + state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) #define __wait_event_common(wq, condition, state, tout) \ ({ \ - DEFINE_WAIT(__wait); \ - long __ret = 0, __tout = tout; \ + long __ret, __tout = tout; \ + wait_queue_t __wait; \ + \ + INIT_LIST_HEAD(&__wait.task_list); \ + __wait.flags = 0; \ \ for (;;) { \ - prepare_to_wait(&wq, &__wait, state); \ + __ret = prepare_to_wait_event(&wq, &__wait, state); \ if (condition) { \ __ret = __wait_no_timeout(tout) ?: __tout ?: 1; \ break; \ } \ \ - if (__wait_signal_pending(state)) { \ - __ret = -ERESTARTSYS; \ + if (__wait_interruptible(state) && __ret) \ break; \ - } \ \ if (__wait_no_timeout(tout)) \ schedule(); \ @@ -781,6 +780,7 @@ extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, * Waitqueues which are removed from the waitqueue_head at wakeup time */ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state); +int prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state); void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state); void finish_wait(wait_queue_head_t *q, wait_queue_t *wait); void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, diff --git a/kernel/wait.c b/kernel/wait.c index 6698e0c..3b8619a 100644 --- a/kernel/wait.c +++ b/kernel/wait.c @@ -78,6 +78,19 @@ prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state) } EXPORT_SYMBOL(prepare_to_wait); +int prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state) +{ + if (signal_pending_state(state, current)) + return -ERESTARTSYS; + + wait->private = current; + wait->func = autoremove_wake_function; + prepare_to_wait(q, wait, state); + + return 0; +} +EXPORT_SYMBOL(prepare_to_wait_event); + void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) { -- 1.5.5.1
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