[PATCH v2] eventdev: fix Rx adapter stalls on event device backpressure

[Jerin Jacob]

On Wed, Nov 10, 2021 at 4:53 PM Jayatheerthan, Jay
<jay.jayatheerthan at intel.com> wrote:
>
> Looks good. Thanks for posting this change!
>
> Acked-by: Jay Jayatheerthan <jay.jayatheerthan at intel.com>


Changed the subject to: eventdev/eth_rx: fix stalls on event device backpressure

Applied to dpdk-next-net-eventdev/for-main. Thanks

>
> > -----Original Message-----
> > From: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
> > Sent: Wednesday, November 10, 2021 4:44 PM
> > To: jerinjacobk at gmail.com; Jayatheerthan, Jay <jay.jayatheerthan at intel.com>; Kundapura, Ganapati
> > <ganapati.kundapura at intel.com>; jerinj at marvell.com
> > Cc: dev @ dpdk . org <dev at dpdk.org>; mattias.ronnblom <mattias.ronnblom at ericsson.com>
> > Subject: [PATCH v2] eventdev: fix Rx adapter stalls on event device backpressure
> >
> > In the Eventdev Ethernet RX Adapter, correctly handle the case where
> > the circular enqueue buffer head and last index point to the same
> > element.
> >
> > This bug may be triggered in case there is backpressure from the event
> > device to the RX adapter.
> >
> > v2:
> > * Corrected bug description
> >
> > Fixes: 8113fd15e229 ("eventdev/eth_rx: make enqueue buffer circular")
> > Cc: ganapati.kundapura at intel.com
> >
> > Signed-off-by: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
> > ---
> >  lib/eventdev/rte_event_eth_rx_adapter.c | 22 ++++++++++++++--------
> >  1 file changed, 14 insertions(+), 8 deletions(-)
> >
> > diff --git a/lib/eventdev/rte_event_eth_rx_adapter.c b/lib/eventdev/rte_event_eth_rx_adapter.c
> > index 56318b5a6f..809416d9b7 100644
> > --- a/lib/eventdev/rte_event_eth_rx_adapter.c
> > +++ b/lib/eventdev/rte_event_eth_rx_adapter.c
> > @@ -777,19 +777,25 @@ rxa_flush_event_buffer(struct event_eth_rx_adapter *rx_adapter,
> >                      struct eth_event_enqueue_buffer *buf,
> >                      struct rte_event_eth_rx_adapter_stats *stats)
> >  {
> > -     uint16_t count = buf->last ? buf->last - buf->head : buf->count;
> > +     uint16_t count = buf->count;
> > +     uint16_t n = 0;
> >
> >       if (!count)
> >               return 0;
> >
> > -     uint16_t n = rte_event_enqueue_new_burst(rx_adapter->eventdev_id,
> > -                                     rx_adapter->event_port_id,
> > -                                     &buf->events[buf->head],
> > -                                     count);
> > -     if (n != count)
> > -             stats->rx_enq_retry++;
> > +     if (buf->last)
> > +             count = buf->last - buf->head;
> > +
> > +     if (count) {
> > +             n = rte_event_enqueue_new_burst(rx_adapter->eventdev_id,
> > +                                             rx_adapter->event_port_id,
> > +                                             &buf->events[buf->head],
> > +                                             count);
> > +             if (n != count)
> > +                     stats->rx_enq_retry++;
> >
> > -     buf->head += n;
> > +             buf->head += n;
> > +     }
> >
> >       if (buf->last && n == count) {
> >               uint16_t n1;
> > --
> > 2.25.1
>