Commit 0cff810f authored Mar 18, 2010 by Lai Jiangshan Committed by Ingo Molnar Mar 18, 2010

rcu: Fix local_irq_disable() CONFIG_PROVE_RCU=y false positives



It is documented that local_irq_disable() also delimits RCU_SCHED
read-site critical sections.

See the document of synchronize_sched() or
Documentation/RCU/whatisRCU.txt.

So we have to test irqs_disabled() in rcu_read_lock_sched_held().
Otherwise rcu-lockdep brings incorrect complaint.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.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
Cc: eric.dumazet@gmail.com
LKML-Reference: <1268940334-10892-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 7f5b7742

include/linux/rcupdate.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -149,7 +149,7 @@ static inline int rcu_read_lock_sched_held(void)
		return 1;
		if (debug_locks)
		lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
		return lockdep_opinion \|\| preempt_count() != 0;
		return lockdep_opinion \|\| preempt_count() != 0 \|\| irqs_disabled();
		}
		#else /* #ifdef CONFIG_PREEMPT */
		static inline int rcu_read_lock_sched_held(void)
		@@ -180,7 +180,7 @@ static inline int rcu_read_lock_bh_held(void)
		#ifdef CONFIG_PREEMPT
		static inline int rcu_read_lock_sched_held(void)
		{
		return !rcu_scheduler_active \|\| preempt_count() != 0;
		return !rcu_scheduler_active \|\| preempt_count() != 0 \|\| irqs_disabled();
		}
		#else /* #ifdef CONFIG_PREEMPT */
		static inline int rcu_read_lock_sched_held(void)

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