The patch titled
Subject: sched/wait: assert the wait_queue_head lock is held in __wake_up_common
has been added to the -mm tree. Its filename is
sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common.patch
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------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: sched/wait: assert the wait_queue_head lock is held in __wake_up_common
Patch series "waitqueue lockdep annotation".
This series adds a strategic lockdep_assert_held to __wake_up_common to
ensure callers really do hold the wait_queue_head lock when calling the
unlocked wake_up variants. It turns out epoll did not do this for a
fairly common path (hit all the time by systemd during bootup), so the
second patch fixed this instance as well.
This patch (of 2):
Better ensure we actually hold the lock using lockdep than just commenting
on it. Due to the various exported _locked interfaces it is far too easy
to get the locking wrong.
Link: http://lkml.kernel.org/r/20171130142037.19339-2-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched/wait.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN kernel/sched/wait.c~sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common kernel/sched/wait.c
--- a/kernel/sched/wait.c~sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common
+++ a/kernel/sched/wait.c
@@ -76,6 +76,8 @@ static int __wake_up_common(struct wait_
wait_queue_entry_t *curr, *next;
int cnt = 0;
+ lockdep_assert_held(&wq_head->lock);
+
if (bookmark && (bookmark->flags & WQ_FLAG_BOOKMARK)) {
curr = list_next_entry(bookmark, entry);
_
Patches currently in -mm which might be from hch@xxxxxx are
sched-wait-assert-the-wait_queue_head-lock-is-held-in-__wake_up_common.patch
epoll-use-proper-wake_up-variant-in-ep_poll_callback.patch
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