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authorJiri Pirko <jpirko@redhat.com>2009-04-14 17:33:57 +0200
committerIngo Molnar <mingo@elte.hu>2009-04-14 18:41:15 +0200
commit72c6a9870f901045f2464c3dc6ee8914bfdc07aa (patch)
tree8bd683fea5f20b17dab613ed8864c016e7b5d369 /include/linux/rculist.h
parent6fd9b3a40b82081d9e6490b0d7cd656e9a78a134 (diff)
downloadop-kernel-dev-72c6a9870f901045f2464c3dc6ee8914bfdc07aa.zip
op-kernel-dev-72c6a9870f901045f2464c3dc6ee8914bfdc07aa.tar.gz
rculist.h: introduce list_entry_rcu() and list_first_entry_rcu()
I've run into the situation where I need to use list_first_entry with rcu-guarded list. This patch introduces this. Also simplify list_for_each_entry_rcu() to use new list_entry_rcu() instead of list_entry(). Signed-off-by: Jiri Pirko <jpirko@redhat.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: dipankar@in.ibm.com LKML-Reference: <20090414153356.GC3999@psychotron.englab.brq.redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/rculist.h')
-rw-r--r--include/linux/rculist.h30
1 files changed, 28 insertions, 2 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e649bd3..5710f43 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -198,6 +198,32 @@ static inline void list_splice_init_rcu(struct list_head *list,
at->prev = last;
}
+/**
+ * list_entry_rcu - get the struct for this entry
+ * @ptr: the &struct list_head pointer.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_entry_rcu(ptr, type, member) \
+ container_of(rcu_dereference(ptr), type, member)
+
+/**
+ * list_first_entry_rcu - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_first_entry_rcu(ptr, type, member) \
+ list_entry_rcu((ptr)->next, type, member)
+
#define __list_for_each_rcu(pos, head) \
for (pos = rcu_dereference((head)->next); \
pos != (head); \
@@ -214,9 +240,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_entry_rcu(pos, head, member) \
- for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \
+ for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
prefetch(pos->member.next), &pos->member != (head); \
- pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member))
+ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**
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