linux-kernel - [PATCH 08/12] task_isolation: don't interrupt CPUs with tick_nohz_full_kick

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Date:   Wed, 4 Mar 2020 16:12:40 +0000
From:   Alex Belits <abelits@...vell.com>
To:     "frederic@...nel.org" <frederic@...nel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>
CC:     "mingo@...nel.org" <mingo@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Prasun Kapoor <pkapoor@...vell.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "linux-mm@...r.kernel.org" <linux-mm@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: [PATCH 08/12] task_isolation: don't interrupt CPUs with
 tick_nohz_full_kick_cpu()

From: Yuri Norov <ynorov@...vell.com>

For nohz_full CPUs the desirable behavior is to receive interrupts
generated by tick_nohz_full_kick_cpu(). But for hard isolation it's
obviously not desirable because it breaks isolation.

This patch adds check for it.

Signed-off-by: Alex Belits <abelits@...vell.com>
---
 kernel/time/tick-sched.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 1d4dec9d3ee7..fe4503ba1316 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -20,6 +20,7 @@
 #include <linux/sched/clock.h>
 #include <linux/sched/stat.h>
 #include <linux/sched/nohz.h>
+#include <linux/isolation.h>
 #include <linux/module.h>
 #include <linux/irq_work.h>
 #include <linux/posix-timers.h>
@@ -262,7 +263,7 @@ static void tick_nohz_full_kick(void)
  */
 void tick_nohz_full_kick_cpu(int cpu)
 {
-	if (!tick_nohz_full_cpu(cpu))
+	if (!tick_nohz_full_cpu(cpu) || task_isolation_on_cpu(cpu))
 		return;
 
 	irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu);
-- 
2.20.1