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Commit 1883c79a authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
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rcu: Make task_subsys_state() RCU-lockdep checks handle boot-time use 



It is apparently legal to invoke task_subsys_state() without RCU
protection during early boot time.  After all, there are no
concurrent tasks, so there can be no grace periods completing
concurrently.

But this does need an Acked-by from the cgroups folks.

Located-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267311188-16603-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 622ea685

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -489,6 +489,7 @@ static inline struct cgroup_subsys_state *task_subsys_state( 
{

	return rcu_dereference_check(task->cgroups->subsys[subsys_id],

				     rcu_read_lock_held() ||

				     !rcu_scheduler_active ||

				     cgroup_lock_is_held());

}