From: Eric Dumazet <edumazet@google.com>
Date: Wed, 11 Sep 2013 21:24:06 +0000 (-0700)
Subject: epoll: add a reschedule point in ep_free()
X-Git-Tag: firefly_0821_release~176^2~5340^2~106
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=91cf5ab60ff82ecf4550a596867787c1e360dd3f;p=firefly-linux-kernel-4.4.55.git

epoll: add a reschedule point in ep_free()

ep_free() might iterate on a huge set of epitems and hold cpu too long.
Add two cond_resched() in order to yield cpu to other tasks.  This is safe
as we only hold mutexes in this function.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 293f86741ddb..473e09da7d02 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -740,6 +740,7 @@ static void ep_free(struct eventpoll *ep)
 		epi = rb_entry(rbp, struct epitem, rbn);
 
 		ep_unregister_pollwait(ep, epi);
+		cond_resched();
 	}
 
 	/*
@@ -754,6 +755,7 @@ static void ep_free(struct eventpoll *ep)
 	while ((rbp = rb_first(&ep->rbr)) != NULL) {
 		epi = rb_entry(rbp, struct epitem, rbn);
 		ep_remove(ep, epi);
+		cond_resched();
 	}
 	mutex_unlock(&ep->mtx);