rcu: Add rcu_pointer_handoff() (c3ac7cf1) · Commits · 戴 / test

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:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

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
		*

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