[dpdk-dev] [PATCH v2] net/virtio: fix an incorrect behavior of device stop/start
Tiwei Bie
tiwei.bie at intel.com
Sat Dec 2 02:24:36 CET 2017
On Wed, Nov 15, 2017 at 01:38:32AM +0800, Fischetti, Antonio wrote:
> Hi Tiwei,
>
> I'm doing some regression tests with v17.11-rc4. I ran
> into a hitch with testpmd running into a guest VM. It happens
> that no packet gets forwarded by testpmd.
> The issue seems to appear after this patch was upstreamed.
>
> I saw there's a way to make it work, ie by avoiding to
> increment the last consumed descriptor:
>
> --- a/drivers/net/virtio/virtqueue.c
> +++ b/drivers/net/virtio/virtqueue.c
> @@ -80,7 +80,7 @@ virtqueue_flush(struct virtqueue *vq)
> rte_pktmbuf_free(dxp->cookie);
> dxp->cookie = NULL;
> }
> - vq->vq_used_cons_idx++;
> + //vq->vq_used_cons_idx++;
> vq_ring_free_chain(vq, desc_idx);
>
> Not quite sure if this change make any sense to you?
>
> Some details below.
>
> The issue appears only if the traffic generator is already
> sending packets before I launch testpmd in the guest.
>
> In my testbench I have Open-vSwitch (OvS-DPDK) which launches
> a VM with 2 vhostuserclient ports (vhu0 and vhu1), each with
> a single queue.
> My OvS has 2 physical ports: dpdk0 and dpdk1.
> dpdk0 forwards packets back and forth from/to the generator
> to/from vhu0.
> Similarly, dpdk1 forwards packets back and forth from/to the generator
> to/from vhu1.
>
> In OvS there are 2 different PMD threads serving the 2
> vhostuserclient ports.
>
> While the traffic generator is already sending packets, in the
> guest VM I launch
> ./testpmd -c 0x3 -n 4 --socket-mem 512 -- --burst=64 -i --txqflags=0xf00 --disable-hw-vlan
>
> The issue is that I see no packet received on the traffic generator
> and in fact testpmd shows
>
> ---------------------- Forward statistics for port 0 ----------------------
> RX-packets: 0 RX-dropped: 0 RX-total: 0
> TX-packets: 0 TX-dropped: 0 TX-total: 0
> ----------------------------------------------------------------------------
>
> ---------------------- Forward statistics for port 1 ----------------------
> RX-packets: 0 RX-dropped: 0 RX-total: 0
> TX-packets: 0 TX-dropped: 0 TX-total: 0
> ----------------------------------------------------------------------------
>
> +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
> RX-packets: 0 RX-dropped: 0 RX-total: 0
> TX-packets: 0 TX-dropped: 0 TX-total: 0
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> Please let me know if I missed something or if you need
> more info on my testbench.
>
Hi Antonio,
I'm very sorry, I missed this mail before.. Thank you so much for
reporting this issue and the detailed info. I'll look into this!
Best regards,
Tiwei Bie
>
> Thanks,
> Antonio
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Tiwei Bie
> > Sent: Friday, October 20, 2017 3:09 AM
> > To: dev at dpdk.org
> > Cc: yliu at fridaylinux.org; maxime.coquelin at redhat.com;
> > jfreimann at redhat.com; stable at dpdk.org
> > Subject: [dpdk-dev] [PATCH v2] net/virtio: fix an incorrect behavior of
> > device stop/start
> >
> > After starting a device, the driver shouldn't deliver the
> > packets that already existed before the device is started
> > to applications. Otherwise it will lead to incorrect packet
> > collection for port state. This patch fixes this issue by
> > flushing the Rx queues when starting the device.
> >
> > Fixes: a85786dc816f ("virtio: fix states handling during
> > initialization")
> > Cc: stable at dpdk.org
> >
> > Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
> > Reviewed-by: Jens Freimann <jfreimann at redhat.com>
> > ---
> > v2:
> > - Use the existing `for` loop
> > - Improve the commit log
> >
> > drivers/net/virtio/virtio_ethdev.c | 2 ++
> > drivers/net/virtio/virtio_rxtx.c | 2 +-
> > drivers/net/virtio/virtqueue.c | 25 +++++++++++++++++++++++++
> > drivers/net/virtio/virtqueue.h | 5 +++++
> > 4 files changed, 33 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/virtio/virtio_ethdev.c
> > b/drivers/net/virtio/virtio_ethdev.c
> > index 42c2836..9ccb0f4 100644
> > --- a/drivers/net/virtio/virtio_ethdev.c
> > +++ b/drivers/net/virtio/virtio_ethdev.c
> > @@ -1819,6 +1819,8 @@ virtio_dev_start(struct rte_eth_dev *dev)
> >
> > for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > rxvq = dev->data->rx_queues[i];
> > + /* Flush the old packets */
> > + virtqueue_flush(rxvq->vq);
> > virtqueue_notify(rxvq->vq);
> > }
> >
> > diff --git a/drivers/net/virtio/virtio_rxtx.c
> > b/drivers/net/virtio/virtio_rxtx.c
> > index 609b413..f5b6f94 100644
> > --- a/drivers/net/virtio/virtio_rxtx.c
> > +++ b/drivers/net/virtio/virtio_rxtx.c
> > @@ -80,7 +80,7 @@ virtio_dev_rx_queue_done(void *rxq, uint16_t offset)
> > return VIRTQUEUE_NUSED(vq) >= offset;
> > }
> >
> > -static void
> > +void
> > vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
> > {
> > struct vring_desc *dp, *dp_tail;
> > diff --git a/drivers/net/virtio/virtqueue.c
> > b/drivers/net/virtio/virtqueue.c
> > index 9ad77b8..c3a536f 100644
> > --- a/drivers/net/virtio/virtqueue.c
> > +++ b/drivers/net/virtio/virtqueue.c
> > @@ -59,3 +59,28 @@ virtqueue_detatch_unused(struct virtqueue *vq)
> > }
> > return NULL;
> > }
> > +
> > +/* Flush the elements in the used ring. */
> > +void
> > +virtqueue_flush(struct virtqueue *vq)
> > +{
> > + struct vring_used_elem *uep;
> > + struct vq_desc_extra *dxp;
> > + uint16_t used_idx, desc_idx;
> > + uint16_t nb_used, i;
> > +
> > + nb_used = VIRTQUEUE_NUSED(vq);
> > +
> > + for (i = 0; i < nb_used; i++) {
> > + used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> > + uep = &vq->vq_ring.used->ring[used_idx];
> > + desc_idx = (uint16_t)uep->id;
> > + dxp = &vq->vq_descx[desc_idx];
> > + if (dxp->cookie != NULL) {
> > + rte_pktmbuf_free(dxp->cookie);
> > + dxp->cookie = NULL;
> > + }
> > + vq->vq_used_cons_idx++;
> > + vq_ring_free_chain(vq, desc_idx);
> > + }
> > +}
> > diff --git a/drivers/net/virtio/virtqueue.h
> > b/drivers/net/virtio/virtqueue.h
> > index 9c4f96d..11059fb 100644
> > --- a/drivers/net/virtio/virtqueue.h
> > +++ b/drivers/net/virtio/virtqueue.h
> > @@ -304,6 +304,9 @@ void virtqueue_dump(struct virtqueue *vq);
> > */
> > struct rte_mbuf *virtqueue_detatch_unused(struct virtqueue *vq);
> >
> > +/* Flush the elements in the used ring. */
> > +void virtqueue_flush(struct virtqueue *vq);
> > +
> > static inline int
> > virtqueue_full(const struct virtqueue *vq)
> > {
> > @@ -312,6 +315,8 @@ virtqueue_full(const struct virtqueue *vq)
> >
> > #define VIRTQUEUE_NUSED(vq) ((uint16_t)((vq)->vq_ring.used->idx - (vq)-
> > >vq_used_cons_idx))
> >
> > +void vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx);
> > +
> > static inline void
> > vq_update_avail_idx(struct virtqueue *vq)
> > {
> > --
> > 2.7.4
>
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