epoll: simplify ep_poll_safewake() for CONFIG_DEBUG_LOCK_ALLOC (f6520c52) · Commits · 戴 / test

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 ("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>

fs/eventpoll.c

+13 −23

Original line number	Diff line number	Diff line
		@@ -551,28 +551,23 @@ out_unlock:
		*/
		#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

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