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[ovs-dev,RFC,v5,2/8] dp-packet: init specific mbuf fields to 0

Message ID 1525194134-248371-3-git-send-email-tiago.lam@intel.com
State Superseded
Delegated to: Ian Stokes
Headers show
Series Support multi-segment mbufs | expand

Commit Message

Lam, Tiago May 1, 2018, 5:02 p.m. UTC 
From: Mark Kavanagh <mark.b.kavanagh@intel.com>

dp_packets are created using xmalloc(); in the case of OvS-DPDK, it's
possible the the resultant mbuf portion of the dp_packet contains
random data. For some mbuf fields, specifically those related to
multi-segment mbufs and/or offload features, random values may cause
unexpected behaviour, should the dp_packet's contents be later copied
to a DPDK mbuf. It is critical therefore, that these fields should be
initialized to 0.

This patch ensures that the following mbuf fields are initialized to 0,
on creation of a new dp_packet:
   - ol_flags
   - nb_segs
   - tx_offload
   - packet_type

Adapted from an idea by Michael Qiu <qiudayu@chinac.com>:
https://patchwork.ozlabs.org/patch/777570/

Co-authored-by: Tiago Lam <tiago.lam@intel.com>

Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
Signed-off-by: Tiago Lam <tiago.lam@intel.com>
---
 lib/dp-packet.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index 21c8ca5..9bfb7b7 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -626,13 +626,13 @@  dp_packet_mbuf_rss_flag_reset(struct dp_packet *p OVS_UNUSED)
 
 /* This initialization is needed for packets that do not come
  * from DPDK interfaces, when vswitchd is built with --with-dpdk.
- * The DPDK rte library will still otherwise manage the mbuf.
- * We only need to initialize the mbuf ol_flags. */
+ * The DPDK rte library will still otherwise manage the mbuf. */
 static inline void
 dp_packet_mbuf_init(struct dp_packet *p OVS_UNUSED)
 {
 #ifdef DPDK_NETDEV
-    p->mbuf.ol_flags = 0;
+    struct rte_mbuf *mbuf = &(p->mbuf);
+    mbuf->ol_flags = mbuf->nb_segs = mbuf->tx_offload = mbuf->packet_type = 0;
 #endif
 }