Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android

[firefly-linux-kernel-4.4.55.git] / include / net / dst.h

diff --git a/include/net/dst.h b/include/net/dst.h
index 1279f9b09791ace6885b0dd67c2c28d578b6cd8e..c7329dcd90cc0637e16fe65eb78246a5d8d21521 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -322,6 +322,39 @@ static inline void skb_dst_force(struct sk_buff *skb)
        }
 }
 
+/**
+ * dst_hold_safe - Take a reference on a dst if possible
+ * @dst: pointer to dst entry
+ *
+ * This helper returns false if it could not safely
+ * take a reference on a dst.
+ */
+static inline bool dst_hold_safe(struct dst_entry *dst)
+{
+       if (dst->flags & DST_NOCACHE)
+               return atomic_inc_not_zero(&dst->__refcnt);
+       dst_hold(dst);
+       return true;
+}
+
+/**
+ * skb_dst_force_safe - makes sure skb dst is refcounted
+ * @skb: buffer
+ *
+ * If dst is not yet refcounted and not destroyed, grab a ref on it.
+ */
+static inline void skb_dst_force_safe(struct sk_buff *skb)
+{
+       if (skb_dst_is_noref(skb)) {
+               struct dst_entry *dst = skb_dst(skb);
+
+               if (!dst_hold_safe(dst))
+                       dst = NULL;
+
+               skb->_skb_refdst = (unsigned long)dst;
+       }
+}
+
 
 /**
  *     __skb_tunnel_rx - prepare skb for rx reinsert