On Fri, Sep 20, 2013 at 11:35 AM, Viresh Kumar <[email protected]> wrote:
> commit 389fbc3c8ad7c339cd2d9572d73c355b7b967823 > Author: Viresh Kumar <[email protected]> > Date: Fri Sep 20 14:55:31 2013 +0530 > > 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). > > Signed-off-by: Viresh Kumar <[email protected]> > --- > drivers/cpufreq/cpufreq.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 82ecbe3..db004a8 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -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; This works! My system boots without crashes after this. Tested-by: Linus Walleij <[email protected]> Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
