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Commit 00f49e57 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
Browse files

rcu: Warn when rcu_read_lock() is used in extended quiescent state 



We are currently able to detect uses of rcu_dereference_check() inside
extended quiescent states (such as the RCU-free window in idle).
But rcu_read_lock() and friends can be used without rcu_dereference(),
so that the earlier commit checking for use of rcu_dereference() and
friends while in RCU idle mode miss some error conditions.  This commit
therefore adds extended quiescent state checking to rcu_read_lock() and
friends.

Uses of RCU from within RCU-idle mode are totally ignored by
RCU, hence the importance of these checks.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 0464e937

include/linux/rcupdate.h

+42 −10
Original line number Diff line number Diff line
@@ -237,21 +237,53 @@ static inline int rcu_is_cpu_idle(void) 
}

#endif /* else !CONFIG_PROVE_RCU */



static inline void rcu_lock_acquire(struct lockdep_map *map)

{

	WARN_ON_ONCE(rcu_is_cpu_idle());

	lock_acquire(map, 0, 0, 2, 1, NULL, _THIS_IP_);

}



static inline void rcu_lock_release(struct lockdep_map *map)

{

	WARN_ON_ONCE(rcu_is_cpu_idle());

	lock_release(map, 1, _THIS_IP_);

}



extern struct lockdep_map rcu_lock_map;

# define rcu_read_acquire() \

		lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)

# define rcu_read_release()	lock_release(&rcu_lock_map, 1, _THIS_IP_)



static inline void rcu_read_acquire(void)

{

	rcu_lock_acquire(&rcu_lock_map);

}



static inline void rcu_read_release(void)

{

	rcu_lock_release(&rcu_lock_map);

}



extern struct lockdep_map rcu_bh_lock_map;

# define rcu_read_acquire_bh() \

		lock_acquire(&rcu_bh_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)

# define rcu_read_release_bh()	lock_release(&rcu_bh_lock_map, 1, _THIS_IP_)



static inline void rcu_read_acquire_bh(void)

{

	rcu_lock_acquire(&rcu_bh_lock_map);

}



static inline void rcu_read_release_bh(void)

{

	rcu_lock_release(&rcu_bh_lock_map);

}



extern struct lockdep_map rcu_sched_lock_map;

# define rcu_read_acquire_sched() \

		lock_acquire(&rcu_sched_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)

# define rcu_read_release_sched() \

		lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)



static inline void rcu_read_acquire_sched(void)

{

	rcu_lock_acquire(&rcu_sched_lock_map);

}



static inline void rcu_read_release_sched(void)

{

	rcu_lock_release(&rcu_sched_lock_map);

}



extern int debug_lockdep_rcu_enabled(void);