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yaml --- r: 288565 b: refs/heads/master c: 5e1ee6e h: refs/heads/master i: 288563: b1b82f3 v: v3
git-mirror · Feb 21, 2012 · 3d50d09 · 3d50d09
1 parent 5ec47ba
commit 3d50d09
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diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 50406b98b6372e7de21d903d2cf3914e9d64e094
+refs/heads/master: 5e1ee6e1016763812018bf5c5e966992821dc47e
diff --git a/trunk/include/linux/rcupdate.h b/trunk/include/linux/rcupdate.h
@@ -484,6 +484,13 @@ static inline void rcu_preempt_sleep_check(void)
  * NULL.  Although rcu_access_pointer() may also be used in cases where
  * update-side locks prevent the value of the pointer from changing, you
  * should instead use rcu_dereference_protected() for this use case.
+ *
+ * It is also permissible to use rcu_access_pointer() when read-side
+ * access to the pointer was removed at least one grace period ago, as
+ * is the case in the context of the RCU callback that is freeing up
+ * the data, or after a synchronize_rcu() returns.  This can be useful
+ * when tearing down multi-linked structures after a grace period
+ * has elapsed.
  */
 #define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu)