From: Paul E. McKenney Date: Sat, 27 Feb 2010 22:53:08 +0000 (-0800) Subject: rcu: Make task_subsys_state() RCU-lockdep checks handle boot-time use X-Git-Tag: v2.6.34-rc2~51^2~14 X-Git-Url: http://git.samba.org/samba.git/?p=sfrench%2Fcifs-2.6.git;a=commitdiff_plain;h=1883c79a57a5fe25309007590cccb1b2782c41b2;ds=sidebyside 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: Ingo Molnar Signed-off-by: Paul E. McKenney 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: Ingo Molnar --- diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c9bbcb2a75ae..a73e1ced09b8 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -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()); }