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From: Davidlohr Bueso <dave@stgolabs.net>
To: Hou Tao <houtao1@huawei.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	viro@zeniv.linux.org.uk, jbaron@akamai.com, oleg@redhat.com,
	koct9i@gmail.com
Subject: Re: [RFC][PATCH 1/8] epoll: remove epmutex from ep_free() & eventpoll_release_file()
Date: Sat, 28 Oct 2017 06:58:54 -0700	[thread overview]
Message-ID: <20171028135854.mpdcngbkozssucrs@linux-n805> (raw)
In-Reply-To: <1509195507-29037-2-git-send-email-houtao1@huawei.com>

On Sat, 28 Oct 2017, Hou Tao wrote:

>Remove the global epmutex from ep_free() and eventpoll_release_file().
>In the later patches, we will add locks with a smaller granularity
>to serve the same purposes of epmutex.
>
>Signed-off-by: Hou Tao <houtao1@huawei.com>
>---
> fs/eventpoll.c | 4 ----
> 1 file changed, 4 deletions(-)
>
>diff --git a/fs/eventpoll.c b/fs/eventpoll.c
>index 2fabd19..26ab0c5 100644
>--- a/fs/eventpoll.c
>+++ b/fs/eventpoll.c
>@@ -835,7 +835,6 @@ static void ep_free(struct eventpoll *ep)
> 	 * anymore. The only hit might come from eventpoll_release_file() but
> 	 * holding "epmutex" is sufficient here.
> 	 */
^^
What about this comment (and the equivalent one in eventpoll_release_file()?

>-	mutex_lock(&epmutex);

...even if you fix it in a later patch, this patch breaks bisection. Now
we just race between ep_free() and eventpoll_release_file(). This patch
should be folded in, no?

Thanks,
Davidlohr

  reply	other threads:[~2017-10-28 13:59 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-28 12:58 [RFC][PATCH 0/8] epoll: remove epmutex from ep_free() and eventpoll_release_file() for non-nested case Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 1/8] epoll: remove epmutex from ep_free() & eventpoll_release_file() Hou Tao
2017-10-28 13:58   ` Davidlohr Bueso [this message]
2017-10-30  7:09     ` Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 2/8] epoll: remove ep from visited_list when freeing ep Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 3/8] epoll: remove file from tfile_check_list when releasing file Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 4/8] epoll: free eventpoll by rcu to provide existence guarantee Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 5/8] epoll: iterate epi in file->f_ep_links by using list_first_or_null_rcu Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 6/8] epoll: ensure the validity of ep when removing epi in eventpoll_release_file() Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 7/8] epoll: prevent the double-free of " Hou Tao
2017-10-28 12:58 ` [RFC][PATCH 8/8] epoll: protect the iteration of ep->rbr by ep->mtx in ep_free() Hou Tao
2017-10-31 13:01 ` [RFC][PATCH 0/8] epoll: remove epmutex from ep_free() and eventpoll_release_file() for non-nested case Davidlohr Bueso

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