[PATCH 1/2] virtio: console: Fix poll blocking even though there is data to read

Rusty Russell
2010-09-20T02:49:33Z

On Thu, 16 Sep 2010 06:43:08 pm Amit Shah wrote:
> From: Hans de Goede <hdegoede at redhat.com>
>
> I found this while working on a Linux agent for spice, the symptom I was
> seeing was select blocking on the spice vdagent virtio serial port even
> though there were messages queued up there.
>
> virtio_console's port_fops_poll checks port->inbuf != NULL to
determine
> if read won't block. However if an application reads enough bytes from
> inbuf through port_fops_read, to empty the current port->inbuf,
> port->inbuf will be NULL even though there may be buffers left in the
> virtqueue.
>
> This causes poll() to block even though there is data to be read,
> this patch fixes this by using will_read_block(port) instead of the
> port->inbuf != NULL check.
>
> Signed-off-By: Hans de Goede <hdegoede at redhat.com>
> Signed-off-by: Amit Shah <amit.shah at redhat.com>

Thanks.  I assume this one should go into stable too?

Cheers,
Rusty.