lkml.org 
[lkml]   [2018]   [Dec]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/3] epoll: make sure all elements in ready list are in FIFO order
Date
All coming events are stored in FIFO order and this is also should be
applicable to ->ovflist, which originally is stack, i.e. LIFO.

Thus to keep correct FIFO order ->ovflist should reversed by adding
elements to the head of the read list but not to the tail.

Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
fs/eventpoll.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 2329f96469e2..3627c2e07149 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -722,7 +722,11 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
* contain them, and the list_splice() below takes care of them.
*/
if (!ep_is_linked(epi)) {
- list_add_tail(&epi->rdllink, &ep->rdllist);
+ /*
+ * ->ovflist is LIFO, so we have to reverse it in order
+ * to keep in FIFO.
+ */
+ list_add(&epi->rdllink, &ep->rdllist);
ep_pm_stay_awake(epi);
}
}
--
2.19.1
\
 
 \ /
  Last update: 2018-12-12 12:05    [W:0.076 / U:24.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site