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epoll: simplify ep_poll_safewake() for CONFIG_DEBUG_LOCK_ALLOC 

Currently, ep_poll_safewake() in the CONFIG_DEBUG_LOCK_ALLOC case uses
ep_call_nested() in order to pass the correct subclass argument to
spin_lock_irqsave_nested().  However, ep_call_nested() adds unnecessary
checks for epoll depth and loops that are already verified when doing
EPOLL_CTL_ADD.  This mirrors a conversion that was done for
!CONFIG_DEBUG_LOCK_ALLOC in: commit 37b5e5212a ("epoll: remove
ep_call_nested() from ep_eventpoll_poll()")

Link: http://lkml.kernel.org/r/1567628549-11501-1-git-send-email-jbaron@akamai.com
Signed-off-by: Jason Baron <jbaron@akamai.com>
Reviewed-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Baron 2019-12-04 16:52:12 -08:00 committed by Linus Torvalds
parent cd28b11904
commit f6520c5208
1 changed files with 13 additions and 23 deletions
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36
fs/eventpoll.c
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@ -551,28 +551,23 @@ static int ep_call_nested(struct nested_calls *ncalls,
*/ */
#ifdef CONFIG_DEBUG_LOCK_ALLOC #ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct nested_calls poll_safewake_ncalls; static DEFINE_PER_CPU(int, wakeup_nest);
static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests)
{
unsigned long flags;
wait_queue_head_t *wqueue = (wait_queue_head_t *)cookie;
spin_lock_irqsave_nested(&wqueue->lock, flags, call_nests + 1);
wake_up_locked_poll(wqueue, EPOLLIN);
spin_unlock_irqrestore(&wqueue->lock, flags);
return 0;
}
static void ep_poll_safewake(wait_queue_head_t *wq) static void ep_poll_safewake(wait_queue_head_t *wq)
{ {
int this_cpu = get_cpu(); unsigned long flags;
int subclass;
ep_call_nested(&poll_safewake_ncalls, local_irq_save(flags);
ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu); preempt_disable();
subclass = __this_cpu_read(wakeup_nest);
put_cpu(); spin_lock_nested(&wq->lock, subclass + 1);
__this_cpu_inc(wakeup_nest);
wake_up_locked_poll(wq, POLLIN);
__this_cpu_dec(wakeup_nest);
spin_unlock(&wq->lock);
local_irq_restore(flags);
preempt_enable();
} }
#else #else
@ -2370,11 +2365,6 @@ static int __init eventpoll_init(void)
*/ */
ep_nested_calls_init(&poll_loop_ncalls); ep_nested_calls_init(&poll_loop_ncalls);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/* Initialize the structure used to perform safe poll wait head wake ups */
ep_nested_calls_init(&poll_safewake_ncalls);
#endif
/* /*
* We can have many thousands of epitems, so prevent this from * We can have many thousands of epitems, so prevent this from
* using an extra cache line on 64-bit (and smaller) CPUs * using an extra cache line on 64-bit (and smaller) CPUs