From: Roman Penyaev <rpenyaev@suse.de>
To: unlisted-recipients:; (no To-header on input)
Cc: Roman Penyaev <rpenyaev@suse.de>, Jason Baron <jbaron@akamai.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/4] epoll: make sure all elements in ready list are in FIFO order
Date: Thu, 3 Jan 2019 16:01:01 +0100 [thread overview]
Message-ID: <20190103150104.17128-2-rpenyaev@suse.de> (raw)
In-Reply-To: <20190103150104.17128-1-rpenyaev@suse.de>
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>
Reviewed-by: 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
next prev parent reply other threads:[~2019-01-03 15:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-03 15:01 [PATCH v2 0/4] use rwlock in order to reduce ep_poll_callback() contention Roman Penyaev
2019-01-03 15:01 ` Roman Penyaev [this message]
2019-01-03 15:01 ` [PATCH v2 2/4] epoll: loosen irq safety in ep_poll_callback() Roman Penyaev
2019-01-03 15:01 ` [PATCH v2 3/4] epoll: unify awaking of wakeup source on ep_poll_callback() path Roman Penyaev
2019-01-03 15:01 ` [PATCH v2 4/4] epoll: use rwlock in order to reduce ep_poll_callback() contention Roman Penyaev
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