[PATCH 2/4] task_work: always use signal work if notification is selected

[Jens Axboe]

Since we run any task_work from get_signal(), there's no real distinction
between TWA_RESUME and TWA_SIGNAL. Turn the notification method for
task_work_add() into a boolean, in preparation for getting rid of the
difference between the two.

With TWA_SIGNAL always being used, we no longer need to check and run
task_work in get_signal() unconditionally. Get rid of it.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 include/linux/task_work.h |  2 +-
 kernel/signal.c           |  3 ---
 kernel/task_work.c        | 29 ++++++++---------------------
 3 files changed, 9 insertions(+), 25 deletions(-)

diff --git a/include/linux/task_work.h b/include/linux/task_work.h
index 0d848a1e9e62..8df8d539fad8 100644
--- a/include/linux/task_work.h
+++ b/include/linux/task_work.h
@@ -20,7 +20,7 @@ enum task_work_notify_mode {
 };
 
 int task_work_add(struct task_struct *task, struct callback_head *twork,
-			enum task_work_notify_mode mode);
+			bool notify);
 
 struct callback_head *task_work_cancel(struct task_struct *, task_work_func_t);
 void task_work_run(void);
diff --git a/kernel/signal.c b/kernel/signal.c
index 6b9c431da08f..5736c55aaa1a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2550,9 +2550,6 @@ bool get_signal(struct ksignal *ksig)
 	struct signal_struct *signal = current->signal;
 	int signr;
 
-	if (unlikely(current->task_works))
-		task_work_run();
-
 	/*
 	 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
 	 * that the arch handlers don't all have to do it. If we get here
diff --git a/kernel/task_work.c b/kernel/task_work.c
index 9cde961875c0..7a4850669033 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -9,15 +9,13 @@ 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: how to notify the targeted task
+ * @notify: whether to notify the targeted task or not
  *
- * Queue @work for task_work_run() below and notify the @task if @notify
- * is @TWA_RESUME or @TWA_SIGNAL. @TWA_SIGNAL works like signals, in that the
- * it will interrupt the targeted task and run the task_work. @TWA_RESUME
- * work is run only when the task exits the kernel and returns to user mode,
- * or before entering guest mode. Fails if the @task is exiting/exited and thus
- * it can't process this @work. Otherwise @work->func() will be called when the
- * @task goes through one of the aforementioned transitions, or exits.
+ * Queue @work for task_work_run() below and notify the @task if @notify is
+ * true. If notification is selected, the targeted task is interrupted so it
+ * can process the work. Fails if the @task is exiting/exited and thus it can't
+ * process this @work. Otherwise @work->func() will be called when the @task
+ * goes through one of the aforementioned transitions, or exits.
  *
  * If the targeted task is exiting, then an error is returned and the work item
  * is not queued. It's up to the caller to arrange for an alternative mechanism
@@ -30,7 +28,7 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */
  * 0 if succeeds or -ESRCH.
  */
 int task_work_add(struct task_struct *task, struct callback_head *work,
-		  enum task_work_notify_mode notify)
+		  bool notify)
 {
 	struct callback_head *head;
 
@@ -41,19 +39,8 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 		work->next = head;
 	} while (cmpxchg(&task->task_works, head, work) != head);
 
-	switch (notify) {
-	case TWA_NONE:
-		break;
-	case TWA_RESUME:
-		set_notify_resume(task);
-		break;
-	case TWA_SIGNAL:
+	if (notify)
 		set_notify_signal(task);
-		break;
-	default:
-		WARN_ON_ONCE(1);
-		break;
-	}
 
 	return 0;
 }
-- 
2.30.0


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