linux-kernel - Re: [PATCHv7 2/4] virtio_console: Use kmalloc instead of kzalloc

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Message-ID: <87d30ahsv1.fsf@rustcorp.com.au>
Date:	Tue, 23 Oct 2012 12:06:34 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	sjur.brandeland@...ricsson.com, Amit Shah <amit.shah@...hat.com>
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Ohad Ben-Cohen <ohad@...ery.com>, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org, sjurbren@...il.com,
	Sjur Brændeland <sjur.brandeland@...ricsson.com>
Subject: Re: [PATCHv7 2/4] virtio_console: Use kmalloc instead of kzalloc

sjur.brandeland@...ricsson.com writes:

> From: Sjur Brændeland <sjur.brandeland@...ricsson.com>
>
> Avoid the more cpu expensive kzalloc when allocating buffers.
> Originally kzalloc was intended for isolating the guest from
> the host by not sending random guest data to the host. But device
> isolation is not yet in place so kzalloc is not really needed.
>
> Signed-off-by: Sjur Brændeland <sjur.brandeland@...ricsson.com>

This looks fine to me.  This is *why* the device gives us the length
which was written; we can trust that, even if we can't trust the
writer of data.

(In theory: noone has implemented such a system, yet).

Applied.
Rusty.

> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index c36b2f6..301d17e 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -349,7 +349,7 @@ static struct port_buffer *alloc_buf(size_t buf_size)
>  	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
>  	if (!buf)
>  		goto fail;
> -	buf->buf = kzalloc(buf_size, GFP_KERNEL);
> +	buf->buf = kmalloc(buf_size, GFP_KERNEL);
>  	if (!buf->buf)
>  		goto free_buf;
>  	buf->len = 0;
> -- 
> 1.7.5.4
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