Commit-ID: c3ac7cf1847a4e68c909984f60d36adef2088e35
Gitweb: http://git.kernel.org/tip/c3ac7cf1847a4e68c909984f60d36adef2088e35
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 10 Sep 2015 16:29:02 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 6 Oct 2015 11:16:18 -0700
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: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcupdate.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 6c3cece..587eb05 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -813,6 +813,28 @@ 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
*
* When synchronize_rcu() is invoked on one CPU while other CPUs
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|