This is needed by bluetooth.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
backport/backport-include/linux/rculist.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/backport/backport-include/linux/rculist.h b/backport/backport-include/linux/rculist.h
index eb3bcfe..74009ab 100644
--- a/backport/backport-include/linux/rculist.h
+++ b/backport/backport-include/linux/rculist.h
@@ -34,4 +34,24 @@
container_of(rcu_dereference(ptr), type, member)
#endif
+#ifndef list_first_or_null_rcu
+/**
+ * list_first_or_null_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 if the list is empty, it returns NULL.
+ *
+ * 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_or_null_rcu(ptr, type, member) \
+({ \
+ struct list_head *__ptr = (ptr); \
+ struct list_head *__next = ACCESS_ONCE(__ptr->next); \
+ likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \
+})
+#endif /* list_first_or_null_rcu */
+
#endif /* __BACKPORT_RCULIST_H */
--
1.9.1
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