Re: [RFC][PATCH 1/8] epoll: remove epmutex from ep_free() & eventpoll_release_file()

[Davidlohr Bueso]

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@xxxxxxxxxx>
> ---
> 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