linux-kernel - [PATCH tip/core/rcu 11/12] arm: Use common outgoing-CPU-notification code

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Message-Id: <20190801223747.15560-11-paulmck@linux.ibm.com>
Date:   Thu,  1 Aug 2019 15:37:46 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        linux-arm-kernel@...ts.infradead.org,
        Russell King <linux@....linux.org.uk>,
        Mark Rutland <mark.rutland@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>
Subject: [PATCH tip/core/rcu 11/12] arm: Use common outgoing-CPU-notification code

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

This commit removes the open-coded CPU-offline notification with new
common code.  In particular, this change avoids calling scheduler code
using RCU from an offline CPU that RCU is ignoring.  This is a minimal
change.  A more intrusive change might invoke the cpu_check_up_prepare()
and cpu_set_state_online() functions at CPU-online time, which would
allow onlining throw an error if the CPU did not go offline properly.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: Russell King <linux@....linux.org.uk>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
---
 arch/arm/kernel/smp.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index aab8ba40ce38..4b0bab2607e4 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -264,15 +264,13 @@ int __cpu_disable(void)
 	return 0;
 }
 
-static DECLARE_COMPLETION(cpu_died);
-
 /*
  * called on the thread which is asking for a CPU to be shutdown -
  * waits until shutdown has completed, or it is timed out.
  */
 void __cpu_die(unsigned int cpu)
 {
-	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
+	if (!cpu_wait_death(cpu, 5)) {
 		pr_err("CPU%u: cpu didn't die\n", cpu);
 		return;
 	}
@@ -319,7 +317,7 @@ void arch_cpu_idle_dead(void)
 	 * this returns, power and/or clocks can be removed at any point
 	 * from this CPU and its cache by platform_cpu_kill().
 	 */
-	complete(&cpu_died);
+	(void)cpu_report_death();
 
 	/*
 	 * Ensure that the cache lines associated with that completion are
-- 
2.17.1