signal: kill JOBCTL_TASK_WORK

It's no longer used, get rid of it.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

include/linux/sched/jobctl.h

@@ -19,7 +19,6 @@ struct task_struct;
 #define JOBCTL_TRAPPING_BIT	21	/* switching to TRACED */
 #define JOBCTL_LISTENING_BIT	22	/* ptracer is listening for events */
 #define JOBCTL_TRAP_FREEZE_BIT	23	/* trap for cgroup freezer */
-#define JOBCTL_TASK_WORK_BIT	24	/* set by TWA_SIGNAL */
 
 #define JOBCTL_STOP_DEQUEUED	(1UL << JOBCTL_STOP_DEQUEUED_BIT)
 #define JOBCTL_STOP_PENDING	(1UL << JOBCTL_STOP_PENDING_BIT)
@@ -29,10 +28,9 @@ struct task_struct;
 #define JOBCTL_TRAPPING		(1UL << JOBCTL_TRAPPING_BIT)
 #define JOBCTL_LISTENING	(1UL << JOBCTL_LISTENING_BIT)
 #define JOBCTL_TRAP_FREEZE	(1UL << JOBCTL_TRAP_FREEZE_BIT)
-#define JOBCTL_TASK_WORK	(1UL << JOBCTL_TASK_WORK_BIT)
 
 #define JOBCTL_TRAP_MASK	(JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
-#define JOBCTL_PENDING_MASK	(JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK | JOBCTL_TASK_WORK)
+#define JOBCTL_PENDING_MASK	(JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)
 
 extern bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask);
 extern void task_clear_jobctl_trapping(struct task_struct *task);

kernel/signal.c

@@ -2556,26 +2556,6 @@ bool get_signal(struct ksignal *ksig)
 
 relock:
 	spin_lock_irq(&sighand->siglock);
-	/*
-	 * Make sure we can safely read ->jobctl() in task_work add. As Oleg
-	 * states:
-	 *
-	 * It pairs with mb (implied by cmpxchg) before READ_ONCE. So we
-	 * roughly have
-	 *
-	 *	task_work_add:				get_signal:
-	 *	STORE(task->task_works, new_work);	STORE(task->jobctl);
-	 *	mb();					mb();
-	 *	LOAD(task->jobctl);			LOAD(task->task_works);
-	 *
-	 * and we can rely on STORE-MB-LOAD [ in task_work_add].
-	 */
-	smp_store_mb(current->jobctl, current->jobctl & ~JOBCTL_TASK_WORK);
-	if (unlikely(current->task_works)) {
-		spin_unlock_irq(&sighand->siglock);
-		task_work_run();
-		goto relock;
-	}
 
 	/*
 	 * Every stopped thread goes here after wakeup. Check to see if