linux-kernel - [PATCH] cpuidle: coupled: fix sleeping while atomic in cpu notifier

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Date:	Wed, 25 Jul 2012 14:20:11 -0700
From:	Colin Cross <ccross@...roid.com>
To:	Len Brown <lenb@...nel.org>
Cc:	Colin Cross <ccross@...roid.com>, Len Brown <len.brown@...el.com>,
	Kevin Hilman <khilman@...com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org
Subject: [PATCH] cpuidle: coupled: fix sleeping while atomic in cpu notifier

The cpu hotplug notifier gets called in both atomic and non-atomic
contexts, it is not always safe to lock a mutex.  Filter out all events
except the six necessary ones, which are all sleepable, before taking
the mutex.

Signed-off-by: Colin Cross <ccross@...roid.com>
---
 drivers/cpuidle/coupled.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
index 2c9bf26..c24dda0 100644
--- a/drivers/cpuidle/coupled.c
+++ b/drivers/cpuidle/coupled.c
@@ -678,6 +678,18 @@ static int cpuidle_coupled_cpu_notify(struct notifier_block *nb,
 	int cpu = (unsigned long)hcpu;
 	struct cpuidle_device *dev;
 
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_UP_PREPARE:
+	case CPU_DOWN_PREPARE:
+	case CPU_ONLINE:
+	case CPU_DEAD:
+	case CPU_UP_CANCELED:
+	case CPU_DOWN_FAILED:
+		break;
+	default:
+		return NOTIFY_OK;
+	}
+
 	mutex_lock(&cpuidle_lock);
 
 	dev = per_cpu(cpuidle_devices, cpu);
-- 
1.7.7.3

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