Re: [PATCH resend] virtio_console: Free buffers from out-queue upon close

From: Rusty Russell
Date: Wed Nov 07 2012 - 19:01:16 EST


sjur.brandeland@xxxxxxxxxxxxxx writes:

> From: Sjur BrÃndeland <sjur.brandeland@xxxxxxxxxxxxxx>
>
> Free pending output buffers from the virtio out-queue when
> host has acknowledged port_close. Also removed WARN_ON()
> in remove_port_data().
>
> Signed-off-by: Sjur BrÃndeland <sjur.brandeland@xxxxxxxxxxxxxx>
> ---
>
> Resending, this time including a proper "Subject"...
> --
>
> Hi Amit,
>
> Note: This patch is compile tested only. I have done the removal
> of buffers from out-queue in handle_control_message()
> when host has acked the close request. This seems less
> racy than doing it in the release function.

This confuses me... why are we doing this in case
VIRTIO_CONSOLE_PORT_OPEN:?

We can't pull unconsumed buffers out of the ring when the other side may
still access it, and this seems to be doing that.

Thanks,
Rusty.
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