Received-SPF: pass (google.com: domain of linux-kernel+bounces-33857-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <20231130070133.8059-1-kch@nvidia.com> <20231130070133.8059-2-kch@nvidia.com>
 <20231201012507.GA1209828@fedora> <f4c17344-33be-4832-9045-fb6b40a478b6@nvidia.com>
In-Reply-To: <f4c17344-33be-4832-9045-fb6b40a478b6@nvidia.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
Date: Mon, 22 Jan 2024 12:47:25 -0500
Message-ID: <CAJSP0QX7H5F=rzz=STeWWYZbTxog0S-MARXgoHkR=u04qTD+_w@mail.gmail.com>
Subject: Re: [RFC PATCH 1/1] virtio-blk: process block layer timedout request
To: Chaitanya Kulkarni <chaitanyak@nvidia.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>, 
	"virtualization@lists.linux.dev" <virtualization@lists.linux.dev>, 
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "mst@redhat.com" <mst@redhat.com>, "hch@lst.de" <hch@lst.de>, 
	"jasowang@redhat.com" <jasowang@redhat.com>, "pbonzini@redhat.com" <pbonzini@redhat.com>, 
	"xuanzhuo@linux.alibaba.com" <xuanzhuo@linux.alibaba.com>, "axboe@kernel.dk" <axboe@kernel.dk>, 
	Ming Lei <ming.lei@redhat.com>
Content-Type: text/plain; charset="UTF-8"

On Mon, 8 Jan 2024 at 22:33, Chaitanya Kulkarni <chaitanyak@nvidia.com> wrote:
> On 11/30/23 17:25, Stefan Hajnoczi wrote:
> > On Wed, Nov 29, 2023 at 11:01:33PM -0800, Chaitanya Kulkarni wrote:
> >> diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
> >> index 3744e4da1b2a..ed864195ab26 100644
> >> --- a/include/uapi/linux/virtio_blk.h
> >> +++ b/include/uapi/linux/virtio_blk.h
> >> @@ -317,6 +317,7 @@ struct virtio_scsi_inhdr {
> >>   #define VIRTIO_BLK_S_OK            0
> >>   #define VIRTIO_BLK_S_IOERR 1
> >>   #define VIRTIO_BLK_S_UNSUPP        2
> >> +#define VIRTIO_BLK_S_TIMEOUT        3
> > The structs and constants in this header file come from the VIRTIO
> > specification. Anything changed in this file must first be accepted into
> > the VIRTIO spec because this is the hardware interface definition.
> >
> > VIRTIO_BLK_S_TIMEOUT seems to be synthetic value that is purely used by
> > software, not the device. Maybe there is no need to update the spec.
> > Just avoid using in_hdr.status to signal timeouts and use a separate
> > flag/field instead in a block layer or virtio_blk driver request struct.
>
> It is a specific error hence I've added that on the similar lines,
> do you have a specific field in mind that you would prefer ?

I didn't have a specific flag or field in mind, but it's probably no
longer necessary in v2 because the code needs to wait for the device
to complete the request anyway.

Stefan