Hi all, The alternate patch from Eric works well too. Even though I didn't see a performance boost compared with the old version, this one is clearer to me. Thanks your guys. Cheers! --Jason On Tue, Jan 1, 2013 at 5:53 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, Jan 1, 2013 at 1:17 PM, Eric Wong <normalperson@xxxxxxxx> wrote: >>> >>> An alternate version (limited to epoll) would be: >>> >>> diff --git a/fs/eventpoll.c b/fs/eventpoll.c >>> index cd96649..ca5f3d0 100644 >>> --- a/fs/eventpoll.c >>> +++ b/fs/eventpoll.c >>> @@ -1299,6 +1299,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even >>> * Get current event bits. We can safely use the file* here because >>> * its usage count has been increased by the caller of this function. >>> */ >>> + smp_mb(); >>> revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt); >>> >>> /* >> >> I was wrong, rereading 626cf236608505d376e4799adb4f7eb00a8594af, >> I think this race existed before. >> >> Perhaps my alternate patch above is a better fix. > > Please document the barrier that this mb() pairs with, and then give > an explanation for the fix in the commit message, and I'll happily > take it. Even if it's just duplicating the comments above the > wq_has_sleeper() function, except modified for the ep_modify() case. > > Of course, it would be good to get verification from Jason and Andreas > that the alternate patch also works for them. > > Linus -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
