Re: [dpdk-dev] [PATCH v1] vhost: add sanity check for resubmiting reqs in split ring

["Liu, Changpeng" <changpeng.liu@intel.com>]

I agree with Maxime, just add an error log doesn't help anything, there might be something wrong in other places,
I don't have the context for this issue, if this can be reproduced in SPDK, I suggest to submit an issue to SPDK first.

> -----Original Message-----
> From: Xia, Chenbo <chenbo.xia@intel.com>
> Sent: Thursday, October 14, 2021 4:28 PM
> To: Maxime Coquelin <maxime.coquelin@redhat.com>; Li Feng
> <fengli@smartx.com>; Liu, Changpeng <changpeng.liu@intel.com>
> Cc: dev@dpdk.org
> Subject: RE: [PATCH v1] vhost: add sanity check for resubmiting reqs in split ring
> 
> Hi Changpeng,
> 
> > -----Original Message-----
> > From: Maxime Coquelin <maxime.coquelin@redhat.com>
> > Sent: Thursday, October 14, 2021 4:26 PM
> > To: Li Feng <fengli@smartx.com>; Xia, Chenbo <chenbo.xia@intel.com>
> > Cc: dev@dpdk.org
> > Subject: Re: [PATCH v1] vhost: add sanity check for resubmiting reqs in split
> > ring
> >
> >
> >
> > On 10/14/21 10:17, Maxime Coquelin wrote:
> > > Hi Li,
> > >
> > > Adding Jin Yu who introduced this function.
> >
> > Looks like Jin Yu has left Intel, Chenbo, could you find someone from
> > the Intel SPDK team to look at it?
> 
> Could you or your team member help check this?
> 
> Thanks,
> Chenbo
> 
> >
> > > On 8/27/21 07:12, Li Feng wrote:
> > >> When getting reqs from the avail ring, the id may exceed inflight
> > >> queue size. Then the dpdk will crash forever.
> > >
> > > You need to add Fixes tag and Cc stable@dpdk.org so that it can be
> > > backported.
> > >
> > >> Signed-off-by: Li Feng <fengli@smartx.com>
> > >> ---
> > >>   lib/vhost/vhost_user.c | 10 ++++++++--
> > >>   1 file changed, 8 insertions(+), 2 deletions(-)
> > >>
> > >> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> > >> index 29a4c9af60..f09d0f6a48 100644
> > >> --- a/lib/vhost/vhost_user.c
> > >> +++ b/lib/vhost/vhost_user.c
> > >> @@ -1823,8 +1823,14 @@ vhost_check_queue_inflights_split(struct
> > >> virtio_net *dev,
> > >>       last_io = inflight_split->last_inflight_io;
> > >>       if (inflight_split->used_idx != used->idx) {
> > >> -        inflight_split->desc[last_io].inflight = 0;
> > >> -        rte_atomic_thread_fence(__ATOMIC_SEQ_CST);
> > >> +        if (unlikely(last_io >= inflight_split->desc_num)) {
> > >> +            VHOST_LOG_CONFIG(ERR, "last_inflight_io '%"PRIu16"'
> > >> exceeds inflight "
> > >> +                "queue size (%"PRIu16").\n", last_io,
> > >> +                inflight_split->desc_num);
> > >
> > > If such error happens, shouldn't we return RTE_VHOST_MSG_RESULT_ERR
> > > instead of just logging an error?
> > >
> > >> +        } else {
> > >> +            inflight_split->desc[last_io].inflight = 0;
> > >> +            rte_atomic_thread_fence(__ATOMIC_SEQ_CST);
> > >> +        }
> > >>           inflight_split->used_idx = used->idx;
> > >>       }
> > >>
> > >
> > > Regards,
> > > Maxime