linux-kernel - [PATCH] cpufreq: return EEXIST instead of EBUSY for second registering

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Message-Id: <1379563520-7221-1-git-send-email-yinghai@kernel.org>
Date:	Wed, 18 Sep 2013 21:05:20 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH] cpufreq: return EEXIST instead of EBUSY for second registering

System that cpu support intel_pstate, acpi_cpufreq fail to
load, and udev keep trying until trace get filled up and
kernel crash.

The root cause is driver return ret from cpufreq_register_driver
and when some other driver take over before, it would return
EBUSY, then udev will keep trying...

cpufreq_register_driver should return EEXIST instead.
then system could boot without appending intel_pstate=disable
and still use intel_pstate.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

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

Index: linux-2.6/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-2.6.orig/drivers/cpufreq/cpufreq.c
+++ linux-2.6/drivers/cpufreq/cpufreq.c
@@ -2104,7 +2104,7 @@ int cpufreq_register_driver(struct cpufr
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	if (cpufreq_driver) {
 		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
-		return -EBUSY;
+		return -EEXIST;
 	}
 	cpufreq_driver = driver_data;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
--
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