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cpufreq: check cpufreq driver is valid and cpufreq isn't disabled in cpufreq_get()

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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>
This commit is contained in:
Viresh Kumar 2013-09-20 22:37:31 +05:30 committed by Rafael J. Wysocki
parent 8a61e12e84
commit 26ca869434
1 changed files with 3 additions and 0 deletions
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3
drivers/cpufreq/cpufreq.c
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@ -1460,6 +1460,9 @@ 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;