The patch titled
Subject: kthread_worker: split code for canceling the delayed work timer
has been removed from the -mm tree. Its filename was
kthread_worker-split-code-for-canceling-the-delayed-work-timer.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Petr Mladek <pmladek@xxxxxxxx>
Subject: kthread_worker: split code for canceling the delayed work timer
Patch series "kthread_worker: Fix race between kthread_mod_delayed_work()
and kthread_cancel_delayed_work_sync()".
This patchset fixes the race between kthread_mod_delayed_work() and
kthread_cancel_delayed_work_sync() including proper return value handling.
This patch (of 2):
Simple code refactoring as a preparation step for fixing a race between
kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync().
It does not modify the existing behavior.
Link: https://lkml.kernel.org/r/20210610133051.15337-2-pmladek@xxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: <jenhaochen@xxxxxxxxxx>
Cc: Martin Liu <liumartin@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kthread.c | 46 ++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)
--- a/kernel/kthread.c~kthread_worker-split-code-for-canceling-the-delayed-work-timer
+++ a/kernel/kthread.c
@@ -1093,6 +1093,33 @@ void kthread_flush_work(struct kthread_w
EXPORT_SYMBOL_GPL(kthread_flush_work);
/*
+ * Make sure that the timer is neither set nor running and could
+ * not manipulate the work list_head any longer.
+ *
+ * The function is called under worker->lock. The lock is temporary
+ * released but the timer can't be set again in the meantime.
+ */
+static void kthread_cancel_delayed_work_timer(struct kthread_work *work,
+ unsigned long *flags)
+{
+ struct kthread_delayed_work *dwork =
+ container_of(work, struct kthread_delayed_work, work);
+ struct kthread_worker *worker = work->worker;
+
+ /*
+ * del_timer_sync() must be called to make sure that the timer
+ * callback is not running. The lock must be temporary released
+ * to avoid a deadlock with the callback. In the meantime,
+ * any queuing is blocked by setting the canceling counter.
+ */
+ work->canceling++;
+ raw_spin_unlock_irqrestore(&worker->lock, *flags);
+ del_timer_sync(&dwork->timer);
+ raw_spin_lock_irqsave(&worker->lock, *flags);
+ work->canceling--;
+}
+
+/*
* This function removes the work from the worker queue. Also it makes sure
* that it won't get queued later via the delayed work's timer.
*
@@ -1106,23 +1133,8 @@ static bool __kthread_cancel_work(struct
unsigned long *flags)
{
/* Try to cancel the timer if exists. */
- if (is_dwork) {
- struct kthread_delayed_work *dwork =
- container_of(work, struct kthread_delayed_work, work);
- struct kthread_worker *worker = work->worker;
-
- /*
- * del_timer_sync() must be called to make sure that the timer
- * callback is not running. The lock must be temporary released
- * to avoid a deadlock with the callback. In the meantime,
- * any queuing is blocked by setting the canceling counter.
- */
- work->canceling++;
- raw_spin_unlock_irqrestore(&worker->lock, *flags);
- del_timer_sync(&dwork->timer);
- raw_spin_lock_irqsave(&worker->lock, *flags);
- work->canceling--;
- }
+ if (is_dwork)
+ kthread_cancel_delayed_work_timer(work, flags);
/*
* Try to remove the work from a worker list. It might either
_
Patches currently in -mm which might be from pmladek@xxxxxxxx are
kthread_worker-fix-return-value-when-kthread_mod_delayed_work-races-with-kthread_cancel_delayed_work_sync.patch
