linux-kernel - [ 35/56] PM / QoS: fix wrong error-checking condition

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Message-Id: <20121130185121.863933752@linuxfoundation.org>
Date:	Fri, 30 Nov 2012 10:55:27 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [ 35/56] PM / QoS: fix wrong error-checking condition

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guennadi Liakhovetski <g.liakhovetski@....de>

commit a7227a0faa117d0bc532aea546ae5ac5f89e8ed7 upstream.

dev_pm_qos_add_request() can return 0, 1, or a negative error code,
therefore the correct error test is "if (error < 0)." Checking just for
non-zero return code leads to erroneous setting of the req->dev pointer
to NULL, which then leads to a repeated call to
dev_pm_qos_add_ancestor_request() in st1232_ts_irq_handler(). This in turn
leads to an Oops, when the I2C host adapter is unloaded and reloaded again
because of the inconsistent state of its QoS request list.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@....de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/base/power/qos.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -446,7 +446,7 @@ int dev_pm_qos_add_ancestor_request(stru
 	if (ancestor)
 		error = dev_pm_qos_add_request(ancestor, req, value);

-	if (error)
+	if (error < 0)
 		req->dev = NULL;

 	return error;

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