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

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Date:	Thu, 8 Nov 2012 10:25:43 +0100
From:	Sjur Brændeland <sjurbren@...il.com>
To:	Amit Shah <amit.shah@...hat.com>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Subject: Re: [PATCH resend] virtio_console: Free buffers from out-queue upon close

>> > 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.
>
> Yes -- and it's my fault; I asked Sjur to do that in the close fops
> function.

Thanks Amit :-), but this was really my bad.

> We should only do this in the port remove case (unplug or device
> remove) -- so the original patch, with just the WARN_ON removed is the
> right way.
>
> I'll send the revised 3/3 patch for you.

Thank you.

Regards,
Sjur
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