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Commit c3ac7cf1 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add rcu_pointer_handoff() 



This commit adds an rcu_pointer_handoff() that is intended to mark
situations where a structure's protection transitions from RCU to some
other mechanism (locking, reference counting, whatever).  These markings
should allow external tools to more easily spot bugs involving leaking
pointers out of RCU read-side critical sections.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent c34d2f41

include/linux/rcupdate.h

+22 −0
Original line number Diff line number Diff line
@@ -812,6 +812,28 @@ static inline void rcu_preempt_sleep_check(void) 
 */

#define rcu_dereference_sched(p) rcu_dereference_sched_check(p, 0)



/**

 * rcu_pointer_handoff() - Hand off a pointer from RCU to other mechanism

 * @p: The pointer to hand off

 *

 * This is simply an identity function, but it documents where a pointer

 * is handed off from RCU to some other synchronization mechanism, for

 * example, reference counting or locking.  In C11, it would map to

 * kill_dependency().  It could be used as follows:

 *

 *	rcu_read_lock();

 *	p = rcu_dereference(gp);

 *	long_lived = is_long_lived(p);

 *	if (long_lived) {

 *		if (!atomic_inc_not_zero(p->refcnt))

 *			long_lived = false;

 *		else

 *			p = rcu_pointer_handoff(p);

 *	}

 *	rcu_read_unlock();

 */

#define rcu_pointer_handoff(p) (p)



/**

 * rcu_read_lock() - mark the beginning of an RCU read-side critical section

 *