backports: rcupdate: Add rcu_replace_pointer
rcu_replace_pointer() was added in upstream commit a63fc6b75cca ("rcu:
Upgrade rcu_swap_protected() to rcu_replace_pointer()") and is now used
by the mt76 driver.
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
diff --git a/backport/backport-include/linux/rcupdate.h b/backport/backport-include/linux/rcupdate.h
index db50100..0bbfd61 100644
--- a/backport/backport-include/linux/rcupdate.h
+++ b/backport/backport-include/linux/rcupdate.h
@@ -77,4 +77,24 @@
} while (0)
#endif
+#ifndef rcu_replace_pointer
+/**
+ * rcu_replace_pointer() - replace an RCU pointer, returning its old value
+ * @rcu_ptr: RCU pointer, whose old value is returned
+ * @ptr: regular pointer
+ * @c: the lockdep conditions under which the dereference will take place
+ *
+ * Perform a replacement, where @rcu_ptr is an RCU-annotated
+ * pointer and @c is the lockdep argument that is passed to the
+ * rcu_dereference_protected() call used to read that pointer. The old
+ * value of @rcu_ptr is returned, and @rcu_ptr is set to @ptr.
+ */
+#define rcu_replace_pointer(rcu_ptr, ptr, c) \
+({ \
+ typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \
+ rcu_assign_pointer((rcu_ptr), (ptr)); \
+ __tmp; \
+})
+#endif
+
#endif /* __BACKPORT_LINUX_RCUPDATE_H */
