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Commit c26d34a5 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu: Add lockdep-enabled variants of rcu_dereference() 



Make rcu_dereference() check for being in an RCU read-side
critical section, and create rcu_dereference_bh(),
rcu_dereference_sched(), and srcu_dereference() to check for the
other flavors of RCU.  Also create rcu_dereference_raw() to
avoid checking, and make rcu_dereference_check() use
rcu_dereference_raw().

Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
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: <1266887105-1528-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 632ee200

include/linux/rcupdate.h

+34 −7
Original line number Diff line number Diff line
@@ -184,12 +184,12 @@ static inline int rcu_read_lock_sched_held(void) 
	({ \

		if (debug_locks) \

			WARN_ON_ONCE(!(c)); \

		rcu_dereference(p); \

		rcu_dereference_raw(p); \

	})



#else /* #ifdef CONFIG_PROVE_RCU */



#define rcu_dereference_check(p, c)	rcu_dereference(p)

#define rcu_dereference_check(p, c)	rcu_dereference_raw(p)



#endif /* #else #ifdef CONFIG_PROVE_RCU */
@@ -325,21 +325,48 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) 




/**

 * rcu_dereference - fetch an RCU-protected pointer in an

 * RCU read-side critical section.  This pointer may later

 * be safely dereferenced.

 * rcu_dereference_raw - fetch an RCU-protected pointer

 *

 * The caller must be within some flavor of RCU read-side critical

 * section, or must be otherwise preventing the pointer from changing,

 * for example, by holding an appropriate lock.  This pointer may later

 * be safely dereferenced.  It is the caller's responsibility to have

 * done the right thing, as this primitive does no checking of any kind.

 *

 * Inserts memory barriers on architectures that require them

 * (currently only the Alpha), and, more importantly, documents

 * exactly which pointers are protected by RCU.

 */



#define rcu_dereference(p)     ({ \

#define rcu_dereference_raw(p)	({ \

				typeof(p) _________p1 = ACCESS_ONCE(p); \

				smp_read_barrier_depends(); \

				(_________p1); \

				})



/**

 * rcu_dereference - fetch an RCU-protected pointer, checking for RCU

 *

 * Makes rcu_dereference_check() do the dirty work.

 */

#define rcu_dereference(p) \

	rcu_dereference_check(p, rcu_read_lock_held())



/**

 * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh

 *

 * Makes rcu_dereference_check() do the dirty work.

 */

#define rcu_dereference_bh(p) \

		rcu_dereference_check(p, rcu_read_lock_bh_held())



/**

 * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched

 *

 * Makes rcu_dereference_check() do the dirty work.

 */

#define rcu_dereference_sched(p) \

		rcu_dereference_check(p, rcu_read_lock_sched_held())



/**

 * rcu_assign_pointer - assign (publicize) a pointer to a newly

 * initialized structure that will be dereferenced by RCU read-side

include/linux/srcu.h

+8 −0
Original line number Diff line number Diff line
@@ -105,6 +105,14 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp) 


#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */



/**

 * srcu_dereference - fetch SRCU-protected pointer with checking

 *

 * Makes rcu_dereference_check() do the dirty work.

 */

#define srcu_dereference(p, sp) \

		rcu_dereference_check(p, srcu_read_lock_held(sp))



/**

 * srcu_read_lock - register a new reader for an SRCU-protected structure.

 * @sp: srcu_struct in which to register the new reader.