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authorRoman Penyaev <rpenyaev@suse.de>2019-03-07 16:28:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-07 18:32:01 -0800
commitc3e320b61581ef7919269ca242ff13951ccfc763 (patch)
treecf1ae4fcfbee8a5d18e109ba1cec26e0fe0114ec
parentc141175d011f18252abb9aa8b018c4e93c71d64b (diff)
download96b-common-c3e320b61581ef7919269ca242ff13951ccfc763.tar.gz
epoll: unify awaking of wakeup source on ep_poll_callback() path
Original comment "Activate ep->ws since epi->ws may get deactivated at any time" indeed sounds loud, but it is incorrect, because the path where we check epi->ws is a path where insert to ovflist happens, i.e. ep_scan_ready_list() has taken ep->mtx and waits for this callback to finish, thus ep_modify() (which unregisters wakeup source) waits for ep_scan_ready_list(). Here in this patch I simply call ep_pm_stay_awake_rcu(), which is a bit extra for this path (indirectly protected by main ep->mtx, so even rcu is not needed), but I do not want to create another naked __ep_pm_stay_awake() variant only for this particular case, so rcu variant is just better for all the cases. Link: http://lkml.kernel.org/r/20190103150104.17128-4-rpenyaev@suse.de 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: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/eventpoll.c9
1 files changed, 1 insertions, 8 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 60f6b2712f5e..53c3d4677dd4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1162,14 +1162,7 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
if (epi->next == EP_UNACTIVE_PTR) {
epi->next = READ_ONCE(ep->ovflist);
WRITE_ONCE(ep->ovflist, epi);
- if (epi->ws) {
- /*
- * Activate ep->ws since epi->ws may get
- * deactivated at any time.
- */
- __pm_stay_awake(ep->ws);
- }
-
+ ep_pm_stay_awake_rcu(epi);
}
goto out_unlock;
}