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| author | Oleg Nesterov <oleg@redhat.com> | 2013-10-07 18:18:24 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-10-16 14:22:18 +0200 |
| commit | c2d816443ef305aba8eaf0bf368f4d3d87494f06 (patch) | |
| tree | 0331463c4ea621c1467e83894a9cebf3a91cb136 /kernel/wait.c | |
| parent | 8922915b38cd8b72f8e5af614b95be71d1d299d4 (diff) | |
| download | lwn-c2d816443ef305aba8eaf0bf368f4d3d87494f06.tar.gz lwn-c2d816443ef305aba8eaf0bf368f4d3d87494f06.zip | |
sched/wait: Introduce prepare_to_wait_event()
Add the new helper, prepare_to_wait_event() which should only be used
by ___wait_event().
prepare_to_wait_event() returns -ERESTARTSYS if signal_pending_state()
is true, otherwise it does prepare_to_wait/exclusive. This allows to
uninline the signal-pending checks in wait_event*() macros.
Also, it can initialize wait->private/func. We do not care if they were
already initialized, the values are the same. This also shaves a couple
of insns from the inlined code.
This obviously makes prepare_*() path a little bit slower, but we are
likely going to sleep anyway, so I think it makes sense to shrink .text:
text data bss dec hex filename
===================================================
before: 5126092 2959248 10117120 18202460 115bf5c vmlinux
after: 5124618 2955152 10117120 18196890 115a99a vmlinux
on my build.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131007161824.GA29757@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/wait.c')
| -rw-r--r-- | kernel/wait.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/wait.c b/kernel/wait.c index d550920e040c..de21c6305a44 100644 --- a/kernel/wait.c +++ b/kernel/wait.c @@ -92,6 +92,30 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) } EXPORT_SYMBOL(prepare_to_wait_exclusive); +long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state) +{ + unsigned long flags; + + if (signal_pending_state(state, current)) + return -ERESTARTSYS; + + wait->private = current; + wait->func = autoremove_wake_function; + + spin_lock_irqsave(&q->lock, flags); + if (list_empty(&wait->task_list)) { + if (wait->flags & WQ_FLAG_EXCLUSIVE) + __add_wait_queue_tail(q, wait); + else + __add_wait_queue(q, wait); + } + set_current_state(state); + spin_unlock_irqrestore(&q->lock, flags); + + return 0; +} +EXPORT_SYMBOL(prepare_to_wait_event); + /** * finish_wait - clean up after waiting in a queue * @q: waitqueue waited on |