On Thu, Jan 16, 2025 at 11:26 PM Stephen Hemminger <
step...@networkplumber.org> wrote:
> On Thu, 16 Jan 2025 23:20:06 +0100
> Ariel Otilibili <ariel.otilib...@6wind.com> wrote:
>
> > Hi Stephen,
> >
> > On Thu, Jan 16, 2025 at 10:47 PM Stephen Hemminger <
> > step...@networkplumber.org> wrote:
> >
> > > On Thu, 16 Jan 2025 20:56:39 +0100
> > > Ariel Otilibili <ariel.otilib...@6wind.com> wrote:
> > >
> > > > Both branches of the loop share the same logic. Now each one is a
> > > > goto dispatcher; either to out (end of function), or to
> > > > stats (continuation of the loop).
> > > >
> > > > Bugzilla ID: 1440
> > > > Depends-on: patch-1 ("net/af_xdp: fix use after free in
> af_xdp_tx_zc()")
> > > > Signed-off-by: Ariel Otilibili <ariel.otilib...@6wind.com>
> > > > ---
> > > > drivers/net/af_xdp/rte_eth_af_xdp.c | 57
> ++++++++++++++---------------
> > > > 1 file changed, 27 insertions(+), 30 deletions(-)
> > > >
> > > > diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c
> > > b/drivers/net/af_xdp/rte_eth_af_xdp.c
> > > > index 4326a29f7042..8b42704b6d9f 100644
> > > > --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> > > > +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> > > > @@ -551,6 +551,7 @@ af_xdp_tx_zc(void *queue, struct rte_mbuf
> **bufs,
> > > uint16_t nb_pkts)
> > > > uint64_t addr, offset;
> > > > struct xsk_ring_cons *cq = &txq->pair->cq;
> > > > uint32_t free_thresh = cq->size >> 1;
> > > > + struct rte_mbuf *local_mbuf = NULL;
> > > >
> > > > if (xsk_cons_nb_avail(cq, free_thresh) >= free_thresh)
> > > > pull_umem_cq(umem, XSK_RING_CONS__DEFAULT_NUM_DESCS,
> cq);
> > > > @@ -565,21 +566,10 @@ af_xdp_tx_zc(void *queue, struct rte_mbuf
> **bufs,
> > > uint16_t nb_pkts)
> > > > &idx_tx))
> > > > goto out;
> > > > }
> > > > - desc = xsk_ring_prod__tx_desc(&txq->tx,
> idx_tx);
> > > > - desc->len = mbuf->pkt_len;
> > > > - addr = (uint64_t)mbuf - (uint64_t)umem->buffer
> -
> > > > - umem->mb_pool->header_size;
> > > > - offset = rte_pktmbuf_mtod(mbuf, uint64_t) -
> > > > - (uint64_t)mbuf +
> > > > - umem->mb_pool->header_size;
> > > > - offset = offset <<
> XSK_UNALIGNED_BUF_OFFSET_SHIFT;
> > > > - desc->addr = addr | offset;
> > > > - tx_bytes += mbuf->pkt_len;
> > > > - count++;
> > > > +
> > > > + goto stats;
> > > > } else {
> > > > - struct rte_mbuf *local_mbuf =
> > > > -
> rte_pktmbuf_alloc(umem->mb_pool);
> > > > - void *pkt;
> > > > + local_mbuf = rte_pktmbuf_alloc(umem->mb_pool);
> > > >
> > > > if (local_mbuf == NULL)
> > > > goto out;
> > > > @@ -589,23 +579,30 @@ af_xdp_tx_zc(void *queue, struct rte_mbuf
> **bufs,
> > > uint16_t nb_pkts)
> > > > goto out;
> > > > }
> > > >
> > > > - desc = xsk_ring_prod__tx_desc(&txq->tx,
> idx_tx);
> > > > - desc->len = mbuf->pkt_len;
> > > > -
> > > > - addr = (uint64_t)local_mbuf -
> > > (uint64_t)umem->buffer -
> > > > - umem->mb_pool->header_size;
> > > > - offset = rte_pktmbuf_mtod(local_mbuf,
> uint64_t) -
> > > > - (uint64_t)local_mbuf +
> > > > - umem->mb_pool->header_size;
> > > > - pkt = xsk_umem__get_data(umem->buffer, addr +
> > > offset);
> > > > - offset = offset <<
> XSK_UNALIGNED_BUF_OFFSET_SHIFT;
> > > > - desc->addr = addr | offset;
> > > > - rte_memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
> > > > - desc->len);
> > > > - tx_bytes += mbuf->pkt_len;
> > > > - rte_pktmbuf_free(mbuf);
> > > > - count++;
> > > > + goto stats;
> > > > }
> > > > +stats:
> > > > + struct rte_mbuf *tmp;
> > > > + void *pkt;
> > > > + tmp = mbuf->pool == umem->mb_pool ? mbuf : local_mbuf;
> > > > +
> > > > + desc = xsk_ring_prod__tx_desc(&txq->tx, idx_tx);
> > > > + desc->len = mbuf->pkt_len;
> > > > +
> > > > + addr = (uint64_t)tmp - (uint64_t)umem->buffer -
> > > umem->mb_pool->header_size;
> > > > + offset = rte_pktmbuf_mtod(tmp, uint64_t) - (uint64_t)tmp +
> > > umem->mb_pool->header_size;
> > > > + offset = offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT;
> > > > + desc->addr = addr | offset;
> > > > +
> > > > + if (mbuf->pool == umem->mb_pool) {
> > > > + tx_bytes += mbuf->pkt_len;
> > > > + } else {
> > > > + pkt = xsk_umem__get_data(umem->buffer, addr + offset);
> > > > + rte_memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
> desc->len);
> > > > + tx_bytes += mbuf->pkt_len;
> > > > + rte_pktmbuf_free(mbuf);
> > > > + }
> > > > + count++;
> > > > }
> > > >
> > > > out:
> > >
> > > Indentation here is wrong, and looks suspect.
> > > Either stats tag should be outside of loop
> > > Or stats is inside loop, and both of those goto's are unnecessary
> > >
> > Thanks for the feedback; I am pushing a new series with an extra tab.
> > So it be obvious that stats belongs to the the loop.
>
>
> But the the goto;s aren't needed? Both legs of the If would fall through
> to that location.
>
You are right, Stephen; thanks for the heads up. I am pushing that change,
without any goto in each leg, so fall through.
Bear with me for some time.
