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 37b5e5212a44 ("epoll: remove
ep_call_nested() from ep_eventpoll_poll()")Signed-off-by: Jason Baron <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Roman Penyaev <[email protected]> Cc: Al Viro <[email protected]> Cc: Eric Wong <[email protected]> Cc: Andrew Morton <[email protected]> --- fs/eventpoll.c | 36 +++++++++++++----------------------- 1 file changed, 13 insertions(+), 23 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index d7f1f50..a9b2737 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -551,28 +551,23 @@ static int ep_call_nested(struct nested_calls *ncalls, */ #ifdef CONFIG_DEBUG_LOCK_ALLOC -static struct nested_calls poll_safewake_ncalls; - -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 DEFINE_PER_CPU(int, wakeup_nest); static void ep_poll_safewake(wait_queue_head_t *wq) { - int this_cpu = get_cpu(); - - ep_call_nested(&poll_safewake_ncalls, - ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu); + unsigned long flags; + int subclass; - put_cpu(); + local_irq_save(flags); + preempt_disable(); + subclass = __this_cpu_read(wakeup_nest); + 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 @@ -2370,11 +2365,6 @@ static int __init eventpoll_init(void) */ 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 * using an extra cache line on 64-bit (and smaller) CPUs -- 2.7.4
