linux-kernel - [RFC][PATCH 1/8] epoll: remove epmutex from ep_free() & eventpoll_release

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Date:   Sat, 28 Oct 2017 20:58:20 +0800
From:   Hou Tao <houtao1@...wei.com>
To:     <linux-fsdevel@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <viro@...iv.linux.org.uk>,
        <jbaron@...mai.com>, <oleg@...hat.com>, <dave@...olabs.net>,
        <koct9i@...il.com>
Subject: [RFC][PATCH 1/8] epoll: remove epmutex from ep_free() & eventpoll_release_file()

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@...wei.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.
 	 */
-	mutex_lock(&epmutex);
 
 	/*
 	 * Walks through the whole tree by unregistering poll callbacks.
@@ -863,7 +862,6 @@ static void ep_free(struct eventpoll *ep)
 	}
 	mutex_unlock(&ep->mtx);
 
-	mutex_unlock(&epmutex);
 	mutex_destroy(&ep->mtx);
 	free_uid(ep->user);
 	wakeup_source_unregister(ep->ws);
@@ -1013,14 +1011,12 @@ void eventpoll_release_file(struct file *file)
 	 *
 	 * Besides, ep_remove() acquires the lock, so we can't hold it here.
 	 */
-	mutex_lock(&epmutex);
 	list_for_each_entry_safe(epi, next, &file->f_ep_links, fllink) {
 		ep = epi->ep;
 		mutex_lock_nested(&ep->mtx, 0);
 		ep_remove(ep, epi);
 		mutex_unlock(&ep->mtx);
 	}
-	mutex_unlock(&epmutex);
 }
 
 static int ep_alloc(struct eventpoll **pep)
-- 
2.7.5