linux-kernel - [PATCH] cpuidle: fix number of initialized/destroyed states

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Message-Id: <1357585921-3391-1-git-send-email-krzysiek@podlesie.net>
Date:	Mon,  7 Jan 2013 20:12:01 +0100
From:	Krzysztof Mazur <krzysiek@...lesie.net>
To:	daniel.lezcano@...aro.org, rafael.j.wysocki@...el.com
Cc:	linux-kernel@...r.kernel.org,
	Krzysztof Mazur <krzysiek@...lesie.net>
Subject: [PATCH] cpuidle: fix number of initialized/destroyed states

Commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92 (cpuidle: support
multiple drivers) changed the number of initialized state kobjects
in cpuidle_add_state_sysfs() from device->state_count to drv->state_count,
but leaved device->state_count in cpuidle_remove_state_sysfs().
Those two values might have different values, causing for instance
NULL pointer dereference in cpuidle_remove_state_sysfs().

Signed-off-by: Krzysztof Mazur <krzysiek@...lesie.net>
---
Hi,

commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92
(cpuidle: support multiple drivers, merged in v3.8-rc1) causes NULL pointer
dereference in cpuidle_remove_state_sysfs() when I plug the AC line to my
laptop. I'm using the acpi_idle cpuidle driver and the C4 state is
available only on when the system runs from battery. The problem still
exists in v3.8-rc2 and f243b9b46a22e5790dbbc36f574c2417af49a41.

I noticed that the commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92
(merged in v3.8-rc1) changed device->state_count to drv->state_count
in only one of two places, which seems to be incorrect. This patch restores
device->state_count in both places. It fixes the problem on my system.

Krzysiek

 drivers/cpuidle/sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 3409429..428754a 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -374,7 +374,7 @@ static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
 	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);

 	/* state statistics */
-	for (i = 0; i < drv->state_count; i++) {
+	for (i = 0; i < device->state_count; i++) {
 		kobj = kzalloc(sizeof(struct cpuidle_state_kobj), GFP_KERNEL);
 		if (!kobj)
 			goto error_state;
-- 
1.8.1.441.g6e0eed0

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