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| author | Oleg Nesterov <oleg@redhat.com> | 2017-06-30 13:13:59 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-07-25 10:08:58 -0700 |
| commit | f274f1e72d7171c80c8c790040e47a23a74796b6 (patch) | |
| tree | 1e69960fc748abd6fd3454a9a782851f200ff92f /kernel/task_work.c | |
| parent | 3ef0c7a730de0bae03d86c19570af764fa3c4445 (diff) | |
| download | lwn-f274f1e72d7171c80c8c790040e47a23a74796b6.tar.gz lwn-f274f1e72d7171c80c8c790040e47a23a74796b6.zip | |
task_work: Replace spin_unlock_wait() with lock/unlock pair
There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair. This commit therefore replaces the spin_unlock_wait() call in
task_work_run() with a spin_lock_irq() and a spin_unlock_irq() aruond
the cmpxchg() dequeue loop. This should be safe from a performance
perspective because ->pi_lock is local to the task and because calls to
the other side of the race, task_work_cancel(), should be rare.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/task_work.c')
| -rw-r--r-- | kernel/task_work.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/kernel/task_work.c b/kernel/task_work.c index d513051fcca2..836a72a66fba 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -96,20 +96,16 @@ void task_work_run(void) * work->func() can do task_work_add(), do not set * work_exited unless the list is empty. */ + raw_spin_lock_irq(&task->pi_lock); do { work = READ_ONCE(task->task_works); head = !work && (task->flags & PF_EXITING) ? &work_exited : NULL; } while (cmpxchg(&task->task_works, work, head) != work); + raw_spin_unlock_irq(&task->pi_lock); if (!work) break; - /* - * Synchronize with task_work_cancel(). It can't remove - * the first entry == work, cmpxchg(task_works) should - * fail, but it can play with *work and other entries. - */ - raw_spin_unlock_wait(&task->pi_lock); do { next = work->next; |