linux-kernel - [PATCH] arm64: Reduce verbosity on SMP CPU stop

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Date:	Fri, 15 Apr 2016 12:24:36 +0200
From:	Jan Glauber <jglauber@...ium.com>
To:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Jan Glauber <jglauber@...ium.com>
Subject: [PATCH] arm64: Reduce verbosity on SMP CPU stop

When CPUs are stopped during an abnormal operation like panic
for each CPU a line is printed and the stack trace is dumped.

This information is only interesting for the aborting CPU
and on systems with many CPUs it only makes it harder to
debug if after the aborting CPU the log is flooded with data
about all other CPUs too.

Therefore remove the stack dump and printk of other CPUs
and only print a single line that the other CPUs are going to be
stopped.

Signed-off-by: Jan Glauber <jglauber@...ium.com>
---
 arch/arm64/kernel/smp.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index b2d5f4e..e6c2eb1 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -770,14 +770,6 @@ static DEFINE_RAW_SPINLOCK(stop_lock);
  */
 static void ipi_cpu_stop(unsigned int cpu)
 {
-	if (system_state == SYSTEM_BOOTING ||
-	    system_state == SYSTEM_RUNNING) {
-		raw_spin_lock(&stop_lock);
-		pr_crit("CPU%u: stopping\n", cpu);
-		dump_stack();
-		raw_spin_unlock(&stop_lock);
-	}
-
 	set_cpu_online(cpu, false);
 
 	local_irq_disable();
@@ -872,6 +864,9 @@ void smp_send_stop(void)
 		cpumask_copy(&mask, cpu_online_mask);
 		cpumask_clear_cpu(smp_processor_id(), &mask);
 
+		if (system_state == SYSTEM_BOOTING ||
+		    system_state == SYSTEM_RUNNING)
+			pr_crit("SMP: stopping secondary CPUs\n");
 		smp_cross_call(&mask, IPI_CPU_STOP);
 	}
 
-- 
1.9.1