On Tue, 16 Apr 2024 20:11:05 +0200
Morten Brørup <m...@smartsharesystems.com> wrote:
> > > > > > static uint16_t
> > > > > > eth_af_packet_tx(void *queue, struct rte_mbuf **bufs, uint16_t
> > > > nb_pkts)
> > > > > > {
> > > > > > ...
> > > > > > for (i = 0; i < nb_pkts; i++) {
> > > > > > mbuf = *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
> > > > below).
> > > > > > So the fix might be - simply insert VLAN tag at copying stage.
> > > > > > Feel free to correct me, if I missed something.
> > > > >
> > > > > vlan_insert will fail if the mbuf is has refcnt > 1.
> > > > >
> > > > > static inline int rte_vlan_insert(struct rte_mbuf **m)
> > > > > {
> > > > > struct rte_ether_hdr *oh, *nh;
> > > > > struct rte_vlan_hdr *vh;
> > > > >
> > > > > /* 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.
> > >
> > > Don't close, silent drop is also a bug.
> > >
> > > The VLAN tag could be insert when copying, as originally suggested.
> >
> > Agree, but to me that would be enhancement request, not a bug report.
>
> Hmm... there is still a bug, although slightly different:
>
> net/af_packet: tx_burst() silently drops packets with RTE_MBUF_F_TX_VLAN if
> mbuf is shared
>
> And the suggested fixes would fix this (other) bug.
In older DPDK, vlan_insert would try and clone the mbuf, but doing a
rte_pktmbuf_clone().
But that was buggy and removed by:
commit 15a74163b12ed9b8b980b1576bdd8de16d60612b
Author: Ferruh Yigit <ferruh.yi...@intel.com>
Date: Tue Apr 16 16:51:26 2019 +0100
net: forbid VLAN insert in shared mbuf
The vlan_insert() is buggy when it tries 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.yi...@intel.com>
Acked-by: Olivier Matz <olivier.m...@6wind.com>
