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 293f86741ddb08a0bc625c3a7fdccbbe96ad7486..473e09da7d02d3396273221f3094824c91f3b030 100644 (file)
--- 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);