linux-kernel - [PATCH RT 07/16] sched/core: Drop a preempt_disable

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Message-Id: <20190719214957.155151346@goodmis.org>
Date:   Fri, 19 Jul 2019 17:49:38 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Julia Cartwright <julia@...com>,
        Daniel Wagner <wagi@...om.org>, tom.zanussi@...ux.intel.com
Subject: [PATCH RT 07/16] sched/core: Drop a preempt_disable_rt() statement

4.19.59-rt24-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

[ Upstream commit 761126efdcbe3fa3e99c9079fa0ad6eca2f251f2 ]

The caller holds a lock which already disables preemption.
Drop the preempt_disable_rt() statement in get_nohz_timer_target().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/sched/core.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 91a9b2556fb0..1b2503b87473 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -558,14 +558,11 @@ void resched_cpu(int cpu)
  */
 int get_nohz_timer_target(void)
 {
-	int i, cpu;
+	int i, cpu = smp_processor_id();
 	struct sched_domain *sd;
 
-	preempt_disable_rt();
-	cpu = smp_processor_id();
-
 	if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER))
-		goto preempt_en_rt;
+		return cpu;
 
 	rcu_read_lock();
 	for_each_domain(cpu, sd) {
@@ -584,8 +581,6 @@ int get_nohz_timer_target(void)
 		cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
 unlock:
 	rcu_read_unlock();
-preempt_en_rt:
-	preempt_enable_rt();
 	return cpu;
 }
 
-- 
2.20.1