From f1093739ff989b8546fcde3d912f13fb6c706a3a Mon Sep 17 00:00:00 2001
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Fri, 20 Sep 2013 22:37:31 +0530
Subject: [PATCH] cpufreq: check cpufreq driver is valid and cpufreq isn't
disabled in cpufreq_get()
cpufreq_get() can be called from external drivers which might not be aware if
cpufreq driver is registered or not. And so we should actually check if cpufreq
driver is registered or not and also if cpufreq is active or disabled, at the
beginning of cpufreq_get().
Otherwise call to lock_policy_rwsem_read() might hit BUG_ON(!policy).
Reported-and-tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Git-commit: 26ca8694344af4c833d22590c5b77d6b9cff0722
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>
---
drivers/cpufreq/cpufreq.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 91420cf13adf..3a8a16cb959f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1489,6 +1489,9 @@ unsigned int cpufreq_get(unsigned int cpu)
{
unsigned int ret_freq = 0;
+ if (cpufreq_disabled() || !cpufreq_driver)
+ return -ENOENT;
+
if (!down_read_trylock(&cpufreq_rwsem))
return 0;
--
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