[PATCH] net: fix rte_vlan_insert with shared mbuf

[Stephen Hemminger <stephen@networkplumber.org>]

If mbuf refcnt was > 1 then rte_vlan_insert() would incorrectly
modify the original copy. Original code was expecting clone to make
a copy (it doesn't). Better to let the caller deal with making
a copy or setting up mbuf chain to allow for header to be added.

Also fix docbook comment about parameters (function takes
pointer to mbuf).

Fixes: c974021a5949 ("ether: add soft vlan encap/decap")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 lib/librte_net/rte_ether.h | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
index c2c5e249ffe9..bab2b198fa79 100644
--- a/lib/librte_net/rte_ether.h
+++ b/lib/librte_net/rte_ether.h
@@ -374,7 +374,7 @@ static inline int rte_vlan_strip(struct rte_mbuf *m)
  * Software version of VLAN unstripping
  *
  * @param m
- *   The packet mbuf.
+ *   Pointer to the packet mbuf.
  * @return
  *   - 0: On success
  *   -EPERM: mbuf is is shared overwriting would be unsafe
@@ -385,16 +385,9 @@ static inline int rte_vlan_insert(struct rte_mbuf **m)
 	struct ether_hdr *oh, *nh;
 	struct vlan_hdr *vh;
 
-	/* Can't insert header if mbuf is shared */
-	if (rte_mbuf_refcnt_read(*m) > 1) {
-		struct rte_mbuf *copy;
-
-		copy = rte_pktmbuf_clone(*m, (*m)->pool);
-		if (unlikely(copy == NULL))
-			return -ENOMEM;
-		rte_pktmbuf_free(*m);
-		*m = copy;
-	}
+	/* Can't directly insert header if mbuf is shared */
+	if (rte_mbuf_refcnt_read(*m) > 1)
+		return -EPERM;
 
 	oh = rte_pktmbuf_mtod(*m, struct ether_hdr *);
 	nh = (struct ether_hdr *)
-- 
2.17.1