| Message ID | 5199E54D.7030407@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 20 May 2013 14:26, Michael Wang <wangyun@linux.vnet.ibm.com> wrote: > On 05/20/2013 03:25 PM, Michael Wang wrote: >> Yeah, that's right, I guess the issue is, although the policy->cpus is >> correct at a given time, after get cpu from it, it's possible to be >> changed, unless we disabled preempt or irq, or hotplug before we use it... >> >> Like such issue cases: >> get x from policy->cpus >> DOWN notifier >> change policy->cpus >> do offline x >> send ipi to x >> >> Will that happen? Sorry I am not sure. :( I can see mutex being used in cpufreq_governor.c which should take care of race conditions... > May be we could do some test to confirm it? > > diff --git a/drivers/cpufreq/cpufreq_governor.c > b/drivers/cpufreq/cpufreq_governor.c > index 443442d..449be88 100644 > --- a/drivers/cpufreq/cpufreq_governor.c > +++ b/drivers/cpufreq/cpufreq_governor.c > @@ -26,6 +26,7 @@ > #include <linux/tick.h> > #include <linux/types.h> > #include <linux/workqueue.h> > +#include <linux/cpu.h> > > #include "cpufreq_governor.h" > > @@ -180,8 +181,10 @@ void gov_queue_work(struct dbs_data *dbs_data, > struct cpufreq_policy *policy, > if (!all_cpus) { > __gov_queue_work(smp_processor_id(), dbs_data, delay); > } else { > + get_online_cpus(); > for_each_cpu(i, policy->cpus) > __gov_queue_work(i, dbs_data, delay); > + put_online_cpus(); > } > } > EXPORT_SYMBOL_GPL(gov_queue_work); > > This is supposed to make WARN disappear, if it works, then BINGO :) Let people test it and then we can talk :) -- 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 05/20/2013 05:09 PM, Viresh Kumar wrote: > On 20 May 2013 14:26, Michael Wang <wangyun@linux.vnet.ibm.com> wrote: >> On 05/20/2013 03:25 PM, Michael Wang wrote: >>> Yeah, that's right, I guess the issue is, although the policy->cpus is >>> correct at a given time, after get cpu from it, it's possible to be >>> changed, unless we disabled preempt or irq, or hotplug before we use it... >>> >>> Like such issue cases: >>> get x from policy->cpus >>> DOWN notifier >>> change policy->cpus >>> do offline x >>> send ipi to x >>> >>> Will that happen? > > Sorry I am not sure. :( > > I can see mutex being used in cpufreq_governor.c which should take care > of race conditions... > >> May be we could do some test to confirm it? >> >> diff --git a/drivers/cpufreq/cpufreq_governor.c >> b/drivers/cpufreq/cpufreq_governor.c >> index 443442d..449be88 100644 >> --- a/drivers/cpufreq/cpufreq_governor.c >> +++ b/drivers/cpufreq/cpufreq_governor.c >> @@ -26,6 +26,7 @@ >> #include <linux/tick.h> >> #include <linux/types.h> >> #include <linux/workqueue.h> >> +#include <linux/cpu.h> >> >> #include "cpufreq_governor.h" >> >> @@ -180,8 +181,10 @@ void gov_queue_work(struct dbs_data *dbs_data, >> struct cpufreq_policy *policy, >> if (!all_cpus) { >> __gov_queue_work(smp_processor_id(), dbs_data, delay); >> } else { >> + get_online_cpus(); >> for_each_cpu(i, policy->cpus) >> __gov_queue_work(i, dbs_data, delay); >> + put_online_cpus(); >> } >> } >> EXPORT_SYMBOL_GPL(gov_queue_work); >> >> This is supposed to make WARN disappear, if it works, then BINGO :) > > Let people test it and then we can talk :) Agree :) Borislav, would you like to take a try? If this fix cause other troubles, you could try get_cpu() or disable irq also. Regards, Michael Wang > -- 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
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 443442d..449be88 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -26,6 +26,7 @@ #include <linux/tick.h> #include <linux/types.h> #include <linux/workqueue.h> +#include <linux/cpu.h> #include "cpufreq_governor.h" @@ -180,8 +181,10 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy, if (!all_cpus) { __gov_queue_work(smp_processor_id(), dbs_data, delay); } else { + get_online_cpus(); for_each_cpu(i, policy->cpus) __gov_queue_work(i, dbs_data, delay); + put_online_cpus(); } }