Commit bc293d62 authored Apr 15, 2010 by Paul E. McKenney Committed by Ingo Molnar Apr 19, 2010

rcu: Make RCU lockdep check the lockdep_recursion variable



The lockdep facility temporarily disables lockdep checking by
incrementing the current->lockdep_recursion variable.  Such
disabling happens in NMIs and in other situations where lockdep
might expect to recurse on itself.

This patch therefore checks current->lockdep_recursion, disabling RCU
lockdep splats when this variable is non-zero.  In addition, this patch
removes the "likely()", as suggested by Lai Jiangshan.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Reported-by: David Miller <davem@davemloft.net>
Tested-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul 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
Cc: eric.dumazet@gmail.com
LKML-Reference: <20100415195039.GA22623@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 50aec002

include/linux/rcupdate.h

+1 −4

Original line number	Diff line number	Diff line
		@@ -101,10 +101,7 @@ extern struct lockdep_map rcu_sched_lock_map;
		# define rcu_read_release_sched() \
		lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)

		static inline int debug_lockdep_rcu_enabled(void)
		{
		return likely(rcu_scheduler_active && debug_locks);
		}
		extern int debug_lockdep_rcu_enabled(void);

		/**
		* rcu_read_lock_held - might we be in RCU read-side critical section?

kernel/rcupdate.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,13 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);

		#ifdef CONFIG_DEBUG_LOCK_ALLOC

		int debug_lockdep_rcu_enabled(void)
		{
		return rcu_scheduler_active && debug_locks &&
		current->lockdep_recursion == 0;
		}
		EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);

		/**
		* rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
		*

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