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From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
To: Stephen Hemminger <stephen@networkplumber.org>
CC: "dev@dpdk.org" <dev@dpdk.org>
Subject: RE: [DPDK/ethdev Bug 1416] net/af_packet: tx_burst() can modify
 packets
Thread-Topic: [DPDK/ethdev Bug 1416] net/af_packet: tx_burst() can modify
 packets
Thread-Index: AQHaj+klsHkMFtD6mEu3P6qfirzOCbFq5v0AgAAmCbA=
Date: Tue, 16 Apr 2024 15:56:06 +0000
Message-ID: <2b4a3bac389141bbae7a2d0ec31df5c6@huawei.com>
References: <bug-1416-3@http.bugs.dpdk.org/>
 <20240416083846.08e8dcad@hermes.local>
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>=20
> > static uint16_t
> > eth_af_packet_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
> > {
> >         ...
> >         for (i =3D 0; i < nb_pkts; i++) {
> >                 mbuf =3D *bufs++;
> >
> >                 ...
> >
> >                 /* insert vlan info if necessary */
> >                 if (mbuf->ol_flags & RTE_MBUF_F_TX_VLAN) {
> >                         if (rte_vlan_insert(&mbuf)) {
> >                                 rte_pktmbuf_free(mbuf);
> >                                 continue;
> >
> > AFAIU, it does copy of mbuf contents into pbuf anyway (just few line be=
low).
> > So the fix might be - simply insert VLAN tag at copying stage.
> > Feel free to correct me, if I missed something.
>=20
> vlan_insert will fail if the mbuf is has refcnt > 1.
>=20
> static inline int rte_vlan_insert(struct rte_mbuf **m)
> {
> 	struct rte_ether_hdr *oh, *nh;
> 	struct rte_vlan_hdr *vh;
>=20
> 	/* Can't insert header if mbuf is shared */
> 	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
> 		return -EINVAL;

You are right, I missed that.
Will close it then.
Thanks
Konstantin