Messages in this thread | | | Subject | Re: [PATCH cpuset] Use rebuild_sched_domains() in cpuset_hotplug_workfn() | From | Li Zhong <> | Date | Mon, 08 Apr 2013 17:51:32 +0800 |
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On Wed, 2013-04-03 at 17:32 +0800, Li Zefan wrote: > On 2013/4/2 15:16, Li Zhong wrote: > > In cpuset_hotplug_workfn(), partition_sched_domains() is called without > > hotplug lock held, which is actually needed (stated in the function > > header of partition_sched_domains()). > > > > This patch tries to use rebuild_sched_domains() to solve the above > > issue, and makes the code looks a little simpler. > > Hi Zefan,
Thanks for your quick review.
> I guess you found this just by code inspection, right?
Ah, yes :)
> The change looks fine and safe at a first glance, but we don't have > time to review the patch for now. > > However I don't know why partition_sched_domains() has to be called > with hotplug lock held. > > After a quick scan, seems the only place in partition_sched_domains() > that might need hotplug lock is arch_update_cpu_topology().
and cpu_attach_domain(), which is called by partition_sched_domains() also states that it needs hotplug lock be held.
It seems that the code is moved out of hotplug critical section after it is converted to work functions.
Thanks, Zhong
> > It would be better if you had CCed the scheduler guys...They may > know the answer. > > > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> > > --- > > kernel/cpuset.c | 13 ++----------- > > 1 files changed, 2 insertions(+), 11 deletions(-) > > > > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > > index 4f9dfe4..515a713 100644 > > --- a/kernel/cpuset.c > > +++ b/kernel/cpuset.c > > @@ -2222,17 +2222,8 @@ static void cpuset_hotplug_workfn(struct work_struct *work) > > flush_workqueue(cpuset_propagate_hotplug_wq); > > > > /* rebuild sched domains if cpus_allowed has changed */ > > - if (cpus_updated) { > > - struct sched_domain_attr *attr; > > - cpumask_var_t *doms; > > - int ndoms; > > - > > - mutex_lock(&cpuset_mutex); > > - ndoms = generate_sched_domains(&doms, &attr); > > - mutex_unlock(&cpuset_mutex); > > - > > - partition_sched_domains(ndoms, doms, attr); > > - } > > + if (cpus_updated) > > + rebuild_sched_domains(); > > } > > > >
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