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Groups > linux.kernel > #1595461
| From | Stefano Stabellini <sstabellini@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 6/7] xen/9pfs: receive responses |
| Date | 2017-03-08 20:30 +0100 |
| Message-ID | <tiPrA-2uR-3@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <ti7gR-4VX-1@gated-at.bofh.it> <ti7gR-4VX-9@gated-at.bofh.it> <tipGN-1c1-15@gated-at.bofh.it> <tiyAp-7Eu-5@gated-at.bofh.it> <tiKUW-7Oh-25@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, 8 Mar 2017, Boris Ostrovsky wrote:
> >>> +
> >>> + if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) < sizeof(h)) {
> >>> + notify_remote_via_irq(ring->irq);
> >>> + return;
> >>> + }
> >>> +
> >>> + masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE);
> >>> + masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
> >>> +
> >>> + xen_9pfs_read_packet(ring->ring.in,
> >>> + masked_prod, &masked_cons,
> >>> + XEN_9PFS_RING_SIZE, &h, sizeof(h));
> >>> +
> >>> + req = p9_tag_lookup(priv->client, h.tag);
> >>> + if (!req || req->status != REQ_STATUS_SENT) {
> >>> + dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
> >>> + cons += h.size;
> >>> + mb();
> >>> + ring->intf->in_cons = cons;
> >>> + continue;
> >>
> >> I don't know what xen_9pfs_read_packet() does so perhaps it's done there
> >> but shouldn't the pointers be updated regardless of the 'if' condition?
> > This is the error path - the index is increased immediately. In the
> > non-error case, we do that right after the next read_packet call, few
> > lines below.
> >
> >
> >>> + }
> >>> +
> >>> + memcpy(req->rc, &h, sizeof(h));
> >>> + req->rc->offset = 0;
> >>> +
> >>> + masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE);
> >>> + xen_9pfs_read_packet(ring->ring.in,
> >>> + masked_prod, &masked_cons,
> >>> + XEN_9PFS_RING_SIZE, req->rc->sdata, h.size);
> >>> +
> >>> + mb();
> >>> + cons += h.size;
> >>> + ring->intf->in_cons = cons;
> > Here ^
> >
>
>
> So the second read is reading again from the same pointer in the ring,
> but this time it gets the whole packet, including the header. The first
> read was just poking at the header. Right?
That's right. First we read the header, to know how much data to read.
> If that's correct, can you add a comment somewhere? (unless this is
> obvious to everyone else but me.)
Sure.
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[PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:10 +0100
[PATCH 1/7] xen: import new ring macros in ring.h Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 7/7] xen/9pfs: build 9pfs Xen transport driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 17:00 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 02:30 +0100
Re: [Xen-devel] [PATCH 6/7] xen/9pfs: receive responses Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2017-03-08 21:20 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 06:30 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:40 +0100
Re: [PATCH 6/7] xen/9pfs: receive responses Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:30 +0100
[PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 22:40 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-06 22:50 +0100
Re: [PATCH 2/7] xen: introduce the header file for the Xen 9pfs transport protocol Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-06 23:40 +0100
[PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 16:10 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 01:30 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:00 +0100
Re: [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:30 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Julien Grall <julien.grall@arm.com> - 2017-03-07 20:00 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 03:20 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Julien Grall <julien.grall@arm.com> - 2017-03-08 13:40 +0100
Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:10 +0100
[PATCH 3/7] xen/9pfs: introduce Xen 9pfs transport driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
[PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-06 21:20 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-07 17:40 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 02:00 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 15:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 20:50 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 21:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 22:10 +0100
Re: [PATCH 5/7] xen/9pfs: send requests to the backend Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 22:30 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Julien Grall <julien.grall@arm.com> - 2017-03-07 20:20 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Stefano Stabellini <sstabellini@kernel.org> - 2017-03-08 01:30 +0100
Re: [Xen-devel] [PATCH 1/7] xen: import new ring macros in ring.h Julien Grall <julien.grall@arm.com> - 2017-03-08 12:50 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Roger Pau Monné <roger.pau@citrix.com> - 2017-03-07 17:50 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-07 19:30 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Roger Pau Monné <roger.pau@citrix.com> - 2017-03-09 04:10 +0100
Re: [Xen-devel] [PATCH 0/7] Xen transport for 9pfs frontend driver Stefano Stabellini <sstabellini@kernel.org> - 2017-03-13 23:40 +0100
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