diff options
| -rw-r--r-- | include/linux/task_work.h | 3 | ||||
| -rw-r--r-- | kernel/task_work.c | 22 |
2 files changed, 17 insertions, 8 deletions
diff --git a/include/linux/task_work.h b/include/linux/task_work.h index fb46b03b1852..ca5a1cf27dae 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -18,8 +18,7 @@ void task_work_run(void); static inline void exit_task_work(struct task_struct *task) { - if (unlikely(task->task_works)) - task_work_run(); + task_work_run(); } #endif /* _LINUX_TASK_WORK_H */ diff --git a/kernel/task_work.c b/kernel/task_work.c index f13ec0bda1d5..65bd3c92d6f3 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -2,16 +2,17 @@ #include <linux/task_work.h> #include <linux/tracehook.h> +static struct callback_head work_exited; /* all we need is ->next == NULL */ + int task_work_add(struct task_struct *task, struct callback_head *work, bool notify) { struct callback_head *head; - /* - * Not inserting the new work if the task has already passed - * exit_task_work() is the responisbility of callers. - */ + do { head = ACCESS_ONCE(task->task_works); + if (unlikely(head == &work_exited)) + return -ESRCH; work->next = head; } while (cmpxchg(&task->task_works, head, work) != head); @@ -30,7 +31,7 @@ task_work_cancel(struct task_struct *task, task_work_func_t func) * If cmpxchg() fails we continue without updating pprev. * Either we raced with task_work_add() which added the * new entry before this work, we will find it again. Or - * we raced with task_work_run(), *pprev == NULL. + * we raced with task_work_run(), *pprev == NULL/exited. */ raw_spin_lock_irqsave(&task->pi_lock, flags); while ((work = ACCESS_ONCE(*pprev))) { @@ -51,7 +52,16 @@ void task_work_run(void) struct callback_head *work, *head, *next; for (;;) { - work = xchg(&task->task_works, NULL); + /* + * work->func() can do task_work_add(), do not set + * work_exited unless the list is empty. + */ + do { + work = ACCESS_ONCE(task->task_works); + head = !work && (task->flags & PF_EXITING) ? + &work_exited : NULL; + } while (cmpxchg(&task->task_works, work, head) != work); + if (!work) break; /* |