The following commit has been merged into the sched/core branch of tip:
Commit-ID: ef73d6a4ef0b35524125c3cfc6deafc26a0c966a
Gitweb: https://git.kernel.org/tip/ef73d6a4ef0b35524125c3cfc6deafc26a0c966a
Author: Arve Hjønnevåg <arve@xxxxxxxxxxx>
AuthorDate: Fri, 02 Jun 2023 21:23:46
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 16 Jun 2023 17:08:01 +02:00
sched/wait: Fix a kthread_park race with wait_woken()
kthread_park and wait_woken have a similar race that
kthread_stop and wait_woken used to have before it was fixed in
commit cb6538e740d7 ("sched/wait: Fix a kthread race with
wait_woken()"). Extend that fix to also cover kthread_park.
[jstultz: Made changes suggested by Peter to optimize
memory loads]
Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>
Signed-off-by: John Stultz <jstultz@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230602212350.535358-1-jstultz@xxxxxxxxxx
---
include/linux/kthread.h | 1 +
kernel/kthread.c | 10 ++++++++++
kernel/sched/wait.c | 7 +------
3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 30e5bec..f1f95a7 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -89,6 +89,7 @@ int kthread_stop(struct task_struct *k);
bool kthread_should_stop(void);
bool kthread_should_park(void);
bool __kthread_should_park(struct task_struct *k);
+bool kthread_should_stop_or_park(void);
bool kthread_freezable_should_stop(bool *was_frozen);
void *kthread_func(struct task_struct *k);
void *kthread_data(struct task_struct *k);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 490792b..07a0570 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -182,6 +182,16 @@ bool kthread_should_park(void)
}
EXPORT_SYMBOL_GPL(kthread_should_park);
+bool kthread_should_stop_or_park(void)
+{
+ struct kthread *kthread = __to_kthread(current);
+
+ if (!kthread)
+ return false;
+
+ return kthread->flags & (BIT(KTHREAD_SHOULD_STOP) | BIT(KTHREAD_SHOULD_PARK));
+}
+
/**
* kthread_freezable_should_stop - should this freezable kthread return now?
* @was_frozen: optional out parameter, indicates whether %current was frozen
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 133b747..48c53e4 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -425,11 +425,6 @@ int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, i
}
EXPORT_SYMBOL(autoremove_wake_function);
-static inline bool is_kthread_should_stop(void)
-{
- return (current->flags & PF_KTHREAD) && kthread_should_stop();
-}
-
/*
* DEFINE_WAIT_FUNC(wait, woken_wake_func);
*
@@ -459,7 +454,7 @@ long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout)
* or woken_wake_function() sees our store to current->state.
*/
set_current_state(mode); /* A */
- if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
+ if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !kthread_should_stop_or_park())
timeout = schedule_timeout(timeout);
__set_current_state(TASK_RUNNING);
|