[dpdk-dev] [PATCH] app/testpmd: fix eth packet dump for small buffers

[dpdk-dev] [PATCH] app/testpmd: fix eth packet dump for small buffers

[David Marchand]

In the rather unlikely case where the first segment is too small to
contain an ethernet header, we can't go and directly dereference the
mbuf data buffer.

Using rte_pktmbuf_read is a little more expensive but this is still
acceptable for a debugging feature.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
 app/test-pmd/util.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/app/test-pmd/util.c b/app/test-pmd/util.c
index a1164b7..18dfdca 100644
--- a/app/test-pmd/util.c
+++ b/app/test-pmd/util.c
@@ -14,7 +14,7 @@
 #include "testpmd.h"
 
 static inline void
-print_ether_addr(const char *what, struct rte_ether_addr *eth_addr)
+print_ether_addr(const char *what, const struct rte_ether_addr *eth_addr)
 {
 	char buf[RTE_ETHER_ADDR_FMT_SIZE];
 	rte_ether_format_addr(buf, RTE_ETHER_ADDR_FMT_SIZE, eth_addr);
@@ -26,7 +26,8 @@
 	      uint16_t nb_pkts, int is_rx)
 {
 	struct rte_mbuf  *mb;
-	struct rte_ether_hdr *eth_hdr;
+	const struct rte_ether_hdr *eth_hdr;
+	struct rte_ether_hdr _eth_hdr;
 	uint16_t eth_type;
 	uint64_t ol_flags;
 	uint16_t i, packet_type;
@@ -46,7 +47,7 @@
 	       (unsigned int) nb_pkts);
 	for (i = 0; i < nb_pkts; i++) {
 		mb = pkts[i];
-		eth_hdr = rte_pktmbuf_mtod(mb, struct rte_ether_hdr *);
+		eth_hdr = rte_pktmbuf_read(mb, 0, sizeof(_eth_hdr), &_eth_hdr);
 		eth_type = RTE_BE_TO_CPU_16(eth_hdr->ether_type);
 		ol_flags = mb->ol_flags;
 		packet_type = mb->packet_type;
-- 
1.8.3.1

Re: [dpdk-dev] [PATCH] app/testpmd: fix eth packet dump for small buffers

[Iremonger, Bernard]

> -----Original Message-----
> From: David Marchand [mailto:david.marchand@redhat.com]
> Sent: Wednesday, July 24, 2019 11:59 AM
> To: dev@dpdk.org
> Cc: olivier.matz@6wind.com; stable@dpdk.org; Lu, Wenzhuo
> <wenzhuo.lu@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Iremonger,
> Bernard <bernard.iremonger@intel.com>
> Subject: [PATCH] app/testpmd: fix eth packet dump for small buffers
> 
> In the rather unlikely case where the first segment is too small to contain an
> ethernet header, we can't go and directly dereference the mbuf data buffer.
> 
> Using rte_pktmbuf_read is a little more expensive but this is still acceptable
> for a debugging feature.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>

Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>

Re: [dpdk-dev] [dpdk-stable] [PATCH] app/testpmd: fix eth packet dump for small buffers

[Thomas Monjalon]

> > In the rather unlikely case where the first segment is too small to contain an
> > ethernet header, we can't go and directly dereference the mbuf data buffer.
> > 
> > Using rte_pktmbuf_read is a little more expensive but this is still acceptable
> > for a debugging feature.
> > 
> > Fixes: af75078fece3 ("first public release")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: David Marchand <david.marchand@redhat.com>
> 
> Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>

Applied, thanks