[dpdk-dev] [PATCH] net: do not insert VLAN tag to shared mbufs

[Ferruh Yigit <ferruh.yigit@intel.com>]

The vlan_insert() is buggy when it tires to handle the shared mbufs,
instead don't support inserting VLAN tag into shared mbufs and return
an error for that case.

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
---
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Chas Williams <chas3@att.com>

This is another approach to RFC to fix the vlan_insert:
https://patches.dpdk.org/patch/51870/

vlan_insert() mostly used by drivers to insert VLAN tag into packet
data in Tx path, drivers creating new copies of mbufs in Tx path may
result unexpected behavior, like not freed or double freed mbufs.
---
 lib/librte_net/rte_ether.h | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
index 3a87ff184..a1df911b6 100644
--- a/lib/librte_net/rte_ether.h
+++ b/lib/librte_net/rte_ether.h
@@ -388,15 +388,8 @@ static inline int rte_vlan_insert(struct rte_mbuf **m)
 	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;
-	}
+	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
+		return -EINVAL;
 
 	oh = rte_pktmbuf_mtod(*m, struct ether_hdr *);
 	nh = (struct ether_hdr *)
-- 
2.20.1