]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
epoll: remove unnecessary xchg
authorTony Battersby <tonyb@cybernetics.com>
Tue, 31 Mar 2009 22:24:15 +0000 (15:24 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 1 Apr 2009 15:59:19 +0000 (08:59 -0700)
commitd1bc90dd5d037079f96b3327f943eb6ae8ef7491
tree0380bd32cee23815b214d81a12b618140c544799
parentd0305882825784e74f68a56eee6c3a812a99f235
epoll: remove unnecessary xchg

xchg in ep_unregister_pollwait() is unnecessary because it is protected by
either epmutex or ep->mtx (the same protection as ep_remove()).

If xchg was necessary, it would be insufficient to protect against
problems: if multiple concurrent calls to ep_unregister_pollwait() were
possible then a second caller that returns without doing anything because
nwait == 0 could return before the waitqueues are removed by the first
caller, which looks like it could lead to problematic races with
ep_poll_callback().

So remove xchg and add comments about the locking.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/eventpoll.c