[RFC] ARM: Don't use complete() during __cpu_die

[Krzysztof Kozlowski]

The complete() should not be used on offlined CPU.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
---
 arch/arm/kernel/smp.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 86ef244c5a24..f3a5ad80a253 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -26,6 +26,7 @@
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
 #include <linux/irq_work.h>
+#include <linux/wait.h>
 
 #include <linux/atomic.h>
 #include <asm/smp.h>
@@ -76,6 +77,9 @@ enum ipi_msg_type {
 
 static DECLARE_COMPLETION(cpu_running);
 
+#define CPU_DIE_WAIT_BIT		0
+static unsigned long wait_cpu_die;
+
 static struct smp_operations smp_ops;
 
 void __init smp_set_ops(struct smp_operations *ops)
@@ -133,7 +137,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 	}
 
-
+	set_bit(CPU_DIE_WAIT_BIT, &wait_cpu_die);
 	memset(&secondary_data, 0, sizeof(secondary_data));
 	return ret;
 }
@@ -213,7 +217,17 @@ int __cpu_disable(void)
 	return 0;
 }
 
-static DECLARE_COMPLETION(cpu_died);
+static int wait_for_cpu_die(void)
+{
+	might_sleep();
+
+	if (!test_bit(CPU_DIE_WAIT_BIT, &wait_cpu_die))
+		return 0;
+
+	return out_of_line_wait_on_bit_timeout(&wait_cpu_die, CPU_DIE_WAIT_BIT,
+					bit_wait_timeout, TASK_UNINTERRUPTIBLE,
+					msecs_to_jiffies(5000));
+}
 
 /*
  * called on the thread which is asking for a CPU to be shutdown -
@@ -221,7 +235,7 @@ static DECLARE_COMPLETION(cpu_died);
  */
 void __cpu_die(unsigned int cpu)
 {
-	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
+	if (wait_for_cpu_die()) {
 		pr_err("CPU%u: cpu didn't die\n", cpu);
 		return;
 	}
@@ -267,7 +281,7 @@ void __ref cpu_die(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);
+	clear_bit(CPU_DIE_WAIT_BIT, &wait_cpu_die);
 
 	/*
 	 * Ensure that the cache lines associated with that completion are
-- 
1.9.1


--Boundary_(ID_cjP6p7DPiBprQ99gyu2RZA)--
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