Re: [win-pv-devel] [PATCH 3/4] Ignore missing requests for responses

[Owen Smith <owen.smith@xxxxxxxxxx>]

> -----Original Message-----
> From: Paul Durrant
> Sent: 17 September 2019 15:57
> To: Owen Smith <owen.smith@xxxxxxxxxx>; win-pv-
> devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> Subject: RE: [win-pv-devel] [PATCH 3/4] Ignore missing requests for
> responses
> 
> > -----Original Message-----
> > From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On
> > Behalf Of Owen Smith
> > Sent: 16 September 2019 16:18
> > To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> > Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> > Subject: [win-pv-devel] [PATCH 3/4] Ignore missing requests for
> > responses
> >
> > Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> > ---
> >  src/xenvbd/ring.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/src/xenvbd/ring.c b/src/xenvbd/ring.c index
> > 3be7c14..d5db1da 100644
> > --- a/src/xenvbd/ring.c
> > +++ b/src/xenvbd/ring.c
> > @@ -1248,11 +1248,10 @@ BlkifRingPoll(
> >
> >              Request = __BlkifRingGetSubmittedRequest(BlkifRing,
> >                                                       rsp->id);
> > -            ASSERT3P(Request, != , NULL);
> > -
> > -            __BlkifRingCompleteResponse(BlkifRing,
> > -                                        Request,
> > -                                        rsp->status);
> > +            if (Request != NULL)
> > +                __BlkifRingCompleteResponse(BlkifRing,
> > +                                            Request,
> > +                                            rsp->status);
> 
> Could you elaborate on when this would happen? If there is a valid response
> on the ring, why would there not be a corresponding request?
> 
>   Paul

This can happen if the requests stored on the SubmittedList are failed before 
responses are received, like when the backend is recreated after a suspend. 
This will only happen with the next patch - I'll combine this and the next for 
v2.

Owen

> 
> >
> >              if (rsp_cons - BlkifRing->Front.rsp_cons > 
> > XENVBD_BATCH(BlkifRing))
> >                  Retry = TRUE;
> > --
> > 2.16.2.windows.1
> >
> >
> > _______________________________________________
> > win-pv-devel mailing list
> > win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> > https://lists.xenproject.org/mailman/listinfo/win-pv-devel
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