cgroup: Check task_lock in task_subsys_state()
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From: Matt Helsley on 22 Apr 2010 23:40 On Fri, Apr 23, 2010 at 10:35:52AM +0800, Li Zefan wrote: > task_subsys_state() is safe under task_lock(). See > Documentation/cgroups/cgroups.txt for locking rule. > > This fixes an RCU warning when resume from suspend. The > warning comes from freezer cgroup in cgroup_freezing_or_frozen(). > > Signed-off-by: Li Zefan <lizf(a)cn.fujitsu.com> Acked-by: Matt Helsley <matthltc(a)us.ibm.com> > --- > > I'm not sure which is preferable - access ->alloc_lock directly > like this patch or add task_lock_is_held() in sched.h > > --- > include/linux/cgroup.h | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index b8ad1ea..8f78073 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state( > { > return rcu_dereference_check(task->cgroups->subsys[subsys_id], > rcu_read_lock_held() || > + lockdep_is_held(&task->alloc_lock) || > cgroup_lock_is_held()); > } > > -- > 1.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Paul E. McKenney on 23 Apr 2010 00:20
On Fri, Apr 23, 2010 at 10:35:52AM +0800, Li Zefan wrote: > task_subsys_state() is safe under task_lock(). See > Documentation/cgroups/cgroups.txt for locking rule. > > This fixes an RCU warning when resume from suspend. The > warning comes from freezer cgroup in cgroup_freezing_or_frozen(). > > Signed-off-by: Li Zefan <lizf(a)cn.fujitsu.com> > --- > > I'm not sure which is preferable - access ->alloc_lock directly > like this patch or add task_lock_is_held() in sched.h This is for the maintainers to decide, either way works from my viewpoint. I have queued it as is with Matt's Acked-by, and am testing it. Thank you!!! Thanx, Paul > --- > include/linux/cgroup.h | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index b8ad1ea..8f78073 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state( > { > return rcu_dereference_check(task->cgroups->subsys[subsys_id], > rcu_read_lock_held() || > + lockdep_is_held(&task->alloc_lock) || > cgroup_lock_is_held()); > } > > -- > 1.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |