> Subject: Re: [PATCH] net/mana: fix wrong indexing on CQE error when coalescing
> is used
>
> On 7/7/2023 1:17 AM, lon...@linuxonhyperv.com wrote:
> > From: Long Li <lon...@microsoft.com>
> >
> > On a fatal CQE error when coalescing is used, update the correct index
> > and allow proceeding to the next CQE.
> >
> > Fixes: 3409e0f172f6 ("net/mana: implement Rx CQE coalescing")
> >
>
> Is above fixes commit correct?
> Logic for 'CQE_RX_COALESCED_4' is not changed with this commit, in above
> commit and in this commit both does breaks the loop.
Yes, the "Fixes" tag is correct. Here CQE_RX_COALESCED_4 is rearranged to make
it easier to read, but it doesn't change the behavior.
>
> This commit changes logic for 'CQE_RX_TRUNCATED' and 'default' cases, which
> are added with different commits, not the one in fixes line.
>
> "fatal CQE error when coalescing" mentioned in the commit log, to which switch
> case does this corresponds to?
The previous patch (3409e0f172f6 ) introduced variable "i", an index to
completion CQEs. But both 'default' and 'CQE_RX_TRUNCATED' cases don't advance
"i", hence not advance to next CQE on error.
The fatal CQE error means the "default" case. On 'CQE_RX_TRUNCATED' the code
can recover when all CQEs are read. But on "default", it's a dead loop.
>
>
> > Signed-off-by: Long Li <lon...@microsoft.com>
> > ---
> > drivers/net/mana/rx.c | 18 ++++++++----------
> > 1 file changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/net/mana/rx.c b/drivers/net/mana/rx.c index
> > cacfd9ae1b..220b372b15 100644
> > --- a/drivers/net/mana/rx.c
> > +++ b/drivers/net/mana/rx.c
> > @@ -416,23 +416,21 @@ mana_rx_burst(void *dpdk_rxq, struct rte_mbuf
> > **pkts, uint16_t pkts_n)
> >
> > switch (oob->cqe_hdr.cqe_type) {
> > case CQE_RX_OKAY:
> > + case CQE_RX_COALESCED_4:
> > /* Proceed to process mbuf */
> > break;
> >
> > case CQE_RX_TRUNCATED:
> > - DP_LOG(DEBUG, "Drop a truncated packet");
> > + default:
> > + DP_LOG(ERR, "RX CQE type %d client %d vendor %d",
> > + oob->cqe_hdr.cqe_type, oob->cqe_hdr.client_type,
> > + oob->cqe_hdr.vendor_err);
> > +
> > rxq->stats.errors++;
> > rte_pktmbuf_free(mbuf);
> > - goto drop;
> > -
> > - case CQE_RX_COALESCED_4:
> > - /* Proceed to process mbuf */
> > - break;
> >
> > - default:
> > - DP_LOG(ERR, "Unknown RX CQE type %d",
> > - oob->cqe_hdr.cqe_type);
> > - continue;
> > + i++;
> > + goto drop;
> > }
> >
> > DP_LOG(DEBUG, "mana_rx_comp_oob type %d rxq %p",
