task_work: documentation
No functional changes, just comments. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -4,6 +4,23 @@
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static struct callback_head work_exited; /* all we need is ->next == NULL */
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/**
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* task_work_add - ask the @task to execute @work->func()
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* @task: the task which should run the callback
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* @work: the callback to run
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* @notify: send the notification if true
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*
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* Queue @work for task_work_run() below and notify the @task if @notify.
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* Fails if the @task is exiting/exited and thus it can't process this @work.
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* Otherwise @work->func() will be called when the @task returns from kernel
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* mode or exits.
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*
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* This is like the signal handler which runs in kernel mode, but it doesn't
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* try to wake up the @task.
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*
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* RETURNS:
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* 0 if succeeds or -ESRCH.
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*/
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int
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task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
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{
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@ -21,6 +38,17 @@ task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
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return 0;
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}
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/**
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* task_work_cancel - cancel a pending work added by task_work_add()
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* @task: the task which should execute the work
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* @func: identifies the work to remove
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*
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* Find the last queued pending work with ->func == @func and remove
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* it from queue.
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*
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* RETURNS:
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* The found work or NULL if not found.
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*/
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struct callback_head *
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task_work_cancel(struct task_struct *task, task_work_func_t func)
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{
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@ -46,6 +74,14 @@ task_work_cancel(struct task_struct *task, task_work_func_t func)
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return work;
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}
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/**
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* task_work_run - execute the works added by task_work_add()
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*
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* Flush the pending works. Should be used by the core kernel code.
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* Called before the task returns to the user-mode or stops, or when
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* it exits. In the latter case task_work_add() can no longer add the
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* new work after task_work_run() returns.
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*/
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void task_work_run(void)
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{
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struct task_struct *task = current;
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