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| author | Jann Horn <jannh@google.com> | 2025-01-29 20:53:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-03-22 12:54:16 -0700 |
| commit | 30a40b59259443035b3450cd8b562e586a446d14 (patch) | |
| tree | 7d0420a0c5a0c80a5705cf5c2cb9cff776ba803e /kernel | |
| parent | c39bd0df25b4760806e7e63d79b5407d9d098158 (diff) | |
| download | linux-30a40b59259443035b3450cd8b562e586a446d14.tar.gz linux-30a40b59259443035b3450cd8b562e586a446d14.tar.bz2 linux-30a40b59259443035b3450cd8b562e586a446d14.zip | |
sched: Clarify wake_up_q()'s write to task->wake_q.next
[ Upstream commit bcc6244e13b4d4903511a1ea84368abf925031c0 ]
Clarify that wake_up_q() does an atomic write to task->wake_q.next, after
which a concurrent __wake_q_add() can immediately overwrite
task->wake_q.next again.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250129-sched-wakeup-prettier-v1-1-2f51f5f663fa@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9803f10a082a..1f817d0c5d2d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1058,9 +1058,10 @@ void wake_up_q(struct wake_q_head *head) struct task_struct *task; task = container_of(node, struct task_struct, wake_q); - /* Task can safely be re-inserted now: */ node = node->next; - task->wake_q.next = NULL; + /* pairs with cmpxchg_relaxed() in __wake_q_add() */ + WRITE_ONCE(task->wake_q.next, NULL); + /* Task can safely be re-inserted now. */ /* * wake_up_process() executes a full barrier, which pairs with |