| Message ID | f428ecb0927075b25cf7e2ea5fb00eab3d254fdd.1436333568.git.viresh.kumar@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Wed, Jul 8, 2015 at 1:53 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > When all CPUs of a policy are hot-unplugged, we EXIT the governor but > don't mark policy->governor as NULL. This was done in order to keep last > used governor's information intact in sysfs, while the CPUs are offline. > > We also missed marking policy->governor as NULL while restoring the > policy. Because of that, we call __cpufreq_governor(CPUFREQ_GOV_LIMITS) > for an uninitialized policy. Which eventually returns -EBUSY. > > Fix this by setting policy->governor to NULL while restoring the policy. Tested-by: "Pi-Cheng Chen <pi-cheng.chen@linaro.org>" Thanks for your fix. > > Reported-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org> > Reported-by: "Jon Medhurst (Tixy)" <tixy@linaro.org> > Fixes: 18bf3a124ef8 ("cpufreq: Mark policy->governor = NULL for inactive policies") > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > For 4.2-rc > > drivers/cpufreq/cpufreq.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index b612411655f9..2c22e3902e72 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1132,6 +1132,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) > > down_write(&policy->rwsem); > policy->cpu = cpu; > + policy->governor = NULL; > up_write(&policy->rwsem); > } > > -- > 2.4.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2015-07-08 at 11:23 +0530, Viresh Kumar wrote: > When all CPUs of a policy are hot-unplugged, we EXIT the governor but > don't mark policy->governor as NULL. This was done in order to keep last > used governor's information intact in sysfs, while the CPUs are offline. > > We also missed marking policy->governor as NULL while restoring the > policy. Because of that, we call __cpufreq_governor(CPUFREQ_GOV_LIMITS) > for an uninitialized policy. Which eventually returns -EBUSY. > > Fix this by setting policy->governor to NULL while restoring the policy. > > Reported-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org> > Reported-by: "Jon Medhurst (Tixy)" <tixy@linaro.org> > Fixes: 18bf3a124ef8 ("cpufreq: Mark policy->governor = NULL for inactive policies") > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- Tested-by: Jon Medhurst <tixy@linaro.org> Thanks for that. I believe this also fixes the other issue I mentioned (nullptr deref in in arm_big_little driver). To test that, after applying this patch, I modified the code to force __cpufreq_governor to still return an error when a cpu is hotpluged back in. Now the arm_big_little driver doesn't get called when I manually poke scaling_setspeed, presumably because policy->governor==NULL prevents that from reaching the driver? > For 4.2-rc > > drivers/cpufreq/cpufreq.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index b612411655f9..2c22e3902e72 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1132,6 +1132,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) > > down_write(&policy->rwsem); > policy->cpu = cpu; > + policy->governor = NULL; > up_write(&policy->rwsem); > } > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08-07-15, 10:27, Jon Medhurst (Tixy) wrote: > I believe this also fixes the other issue I mentioned (nullptr deref in > in arm_big_little driver). To test that, after applying this patch, I > modified the code to force __cpufreq_governor to still return an error > when a cpu is hotpluged back in. Now the arm_big_little driver doesn't > get called when I manually poke scaling_setspeed, presumably because > policy->governor==NULL prevents that from reaching the driver? I would like to fix that issue without using this patch as we aren't cleaning up things properly on errors today. I am almost done with the patches, and will send them to you shortly. Please give them a try without this patch.
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index b612411655f9..2c22e3902e72 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1132,6 +1132,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) down_write(&policy->rwsem); policy->cpu = cpu; + policy->governor = NULL; up_write(&policy->rwsem); }
When all CPUs of a policy are hot-unplugged, we EXIT the governor but don't mark policy->governor as NULL. This was done in order to keep last used governor's information intact in sysfs, while the CPUs are offline. We also missed marking policy->governor as NULL while restoring the policy. Because of that, we call __cpufreq_governor(CPUFREQ_GOV_LIMITS) for an uninitialized policy. Which eventually returns -EBUSY. Fix this by setting policy->governor to NULL while restoring the policy. Reported-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org> Reported-by: "Jon Medhurst (Tixy)" <tixy@linaro.org> Fixes: 18bf3a124ef8 ("cpufreq: Mark policy->governor = NULL for inactive policies") Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- For 4.2-rc drivers/cpufreq/cpufreq.c | 1 + 1 file changed, 1 insertion(+)