linux-kernel - [PATCH v2 3/3] sched: Remove rq.hrtick_csd

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Message-Id: <20191216213125.9536-4-peterx@redhat.com>
Date:   Mon, 16 Dec 2019 16:31:25 -0500
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Juri Lelli <juri.lelli@...hat.com>, peterx@...hat.com,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v2 3/3] sched: 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@...hat.com>
---
 kernel/sched/core.c  | 9 ++-------
 kernel/sched/sched.h | 1 -
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 44123b4d14e8..ef527545d349 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -268,7 +268,6 @@ static void __hrtick_start(void *arg)
 
 	rq_lock(rq, &rf);
 	__hrtick_restart(rq);
-	rq->hrtick_csd_pending = 0;
 	rq_unlock(rq, &rf);
 }
 
@@ -292,12 +291,10 @@ 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
@@ -321,8 +318,6 @@ 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;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c8870c5bd7df..79b435bbe129 100644
--- a/kernel/sched/sched.h
+++ b/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;
-- 
2.23.0