task_work: remove legacy TWA_SIGNAL path

All archs now support TIF_NOTIFY_SIGNAL.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/kernel/task_work.c b/kernel/task_work.c
index 15b0872..9cde961 100644 (file)
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -5,34 +5,6 @@
 
 static struct callback_head work_exited; /* all we need is ->next == NULL */
 
-/*
- * TWA_SIGNAL signaling - use TIF_NOTIFY_SIGNAL, if available, as it's faster
- * than TIF_SIGPENDING as there's no dependency on ->sighand. The latter is
- * shared for threads, and can cause contention on sighand->lock. Even for
- * the non-threaded case TIF_NOTIFY_SIGNAL is more efficient, as no locking
- * or IRQ disabling is involved for notification (or running) purposes.
- */
-static void task_work_notify_signal(struct task_struct *task)
-{
-#if defined(TIF_NOTIFY_SIGNAL)
-       set_notify_signal(task);
-#else
-       unsigned long flags;
-
-       /*
-        * Only grab the sighand lock if we don't already have some
-        * task_work pending. This pairs with the smp_store_mb()
-        * in get_signal(), see comment there.
-        */
-       if (!(READ_ONCE(task->jobctl) & JOBCTL_TASK_WORK) &&
-           lock_task_sighand(task, &flags)) {
-               task->jobctl |= JOBCTL_TASK_WORK;
-               signal_wake_up(task, 0);
-               unlock_task_sighand(task, &flags);
-       }
-#endif
-}
-
 /**
  * task_work_add - ask the @task to execute @work->func()
  * @task: the task which should run the callback
@@ -76,7 +48,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
                set_notify_resume(task);
                break;
        case TWA_SIGNAL:
-               task_work_notify_signal(task);
+               set_notify_signal(task);
                break;
        default:
                WARN_ON_ONCE(1);