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authorOleg Nesterov <oleg@redhat.com>2013-09-11 14:23:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:58:27 -0700
commit892f6668f3a7088c7e30049c3d8e1844531602dc (patch)
tree68ad5c81f3bccaae821a891f1611135056829dc0 /kernel
parenttask_work: minor cleanups (diff)
downloadlinux-dev-892f6668f3a7088c7e30049c3d8e1844531602dc.tar.xz
linux-dev-892f6668f3a7088c7e30049c3d8e1844531602dc.zip
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/task_work.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/kernel/task_work.c b/kernel/task_work.c
index 6ee09856f725..8727032e3a6f 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -4,6 +4,23 @@
static struct callback_head work_exited; /* all we need is ->next == NULL */
+/**
+ * task_work_add - ask the @task to execute @work->func()
+ * @task: the task which should run the callback
+ * @work: the callback to run
+ * @notify: send the notification if true
+ *
+ * Queue @work for task_work_run() below and notify the @task if @notify.
+ * Fails if the @task is exiting/exited and thus it can't process this @work.
+ * Otherwise @work->func() will be called when the @task returns from kernel
+ * mode or exits.
+ *
+ * This is like the signal handler which runs in kernel mode, but it doesn't
+ * try to wake up the @task.
+ *
+ * RETURNS:
+ * 0 if succeeds or -ESRCH.
+ */
int
task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
{
@@ -21,6 +38,17 @@ task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
return 0;
}
+/**
+ * task_work_cancel - cancel a pending work added by task_work_add()
+ * @task: the task which should execute the work
+ * @func: identifies the work to remove
+ *
+ * Find the last queued pending work with ->func == @func and remove
+ * it from queue.
+ *
+ * RETURNS:
+ * The found work or NULL if not found.
+ */
struct callback_head *
task_work_cancel(struct task_struct *task, task_work_func_t func)
{
@@ -46,6 +74,14 @@ task_work_cancel(struct task_struct *task, task_work_func_t func)
return work;
}
+/**
+ * task_work_run - execute the works added by task_work_add()
+ *
+ * Flush the pending works. Should be used by the core kernel code.
+ * Called before the task returns to the user-mode or stops, or when
+ * it exits. In the latter case task_work_add() can no longer add the
+ * new work after task_work_run() returns.
+ */
void task_work_run(void)
{
struct task_struct *task = current;