sched/core: Remove rq.hrtick_csd_pending

Now smp_call_function_single_async() provides the protection that
we'll return with -EBUSY if the csd object is still pending, then we
don't need the rq.hrtick_csd_pending any more.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20191216213125.9536-4-peterx@redhat.com

kernel/sched/core.c

@@ -269,7 +269,6 @@ static void __hrtick_start(void *arg)
 
 	rq_lock(rq, &rf);
 	__hrtick_restart(rq);
-	rq->hrtick_csd_pending = 0;
 	rq_unlock(rq, &rf);
 }
 
@@ -293,12 +292,10 @@ void hrtick_start(struct rq *rq, u64 delay)
 
 	hrtimer_set_expires(timer, time);
 
-	if (rq == this_rq()) {
+	if (rq == this_rq())
 		__hrtick_restart(rq);
-	} else if (!rq->hrtick_csd_pending) {
+	else
 		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
-		rq->hrtick_csd_pending = 1;
-	}
 }
 
 #else
@@ -322,8 +319,6 @@ void hrtick_start(struct rq *rq, u64 delay)
 static void hrtick_rq_init(struct rq *rq)
 {
 #ifdef CONFIG_SMP
-	rq->hrtick_csd_pending = 0;
-
 	rq->hrtick_csd.flags = 0;
 	rq->hrtick_csd.func = __hrtick_start;
 	rq->hrtick_csd.info = rq;

kernel/sched/sched.h

@@ -967,7 +967,6 @@ struct rq {
 
 #ifdef CONFIG_SCHED_HRTICK
 #ifdef CONFIG_SMP
-	int			hrtick_csd_pending;
 	call_single_data_t	hrtick_csd;
 #endif
 	struct hrtimer		hrtick_timer;