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| author | Roman Penyaev <rpenyaev@suse.de> | 2019-03-08 03:28:49 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-08 05:32:01 +0300 |
| commit | c3e320b61581ef7919269ca242ff13951ccfc763 (patch) | |
| tree | cf1ae4fcfbee8a5d18e109ba1cec26e0fe0114ec /fs/eventpoll.c | |
| parent | c141175d011f18252abb9aa8b018c4e93c71d64b (diff) | |
| download | linux-c3e320b61581ef7919269ca242ff13951ccfc763.tar.xz | |
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>
Diffstat (limited to 'fs/eventpoll.c')
| -rw-r--r-- | fs/eventpoll.c | 9 |
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; } |