diff options
| author | Jann Horn <jannh@google.com> | 2025-01-29 20:53:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-03-22 12:56:47 -0700 |
| commit | 44eee071fa6a21d8840c0051693018de541409b6 (patch) | |
| tree | df11b4f43dc910a0841923bd16fb61d7bf2292f2 | |
| parent | d8f12a29670c24a2df5de0d4a7761b8ad9218dd4 (diff) | |
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>
| -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 86cb6db08168..4b5878b2fdd0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1057,9 +1057,10 @@ 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 |