linux-kernel - Re: [PATCH 2/2] [BUGFIX] virtio/console: Add pipe_lock/unlock for splice

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Date:	Fri, 19 Jul 2013 10:53:12 +0530
From:	Amit Shah <amit.shah@...hat.com>
To:	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
Cc:	linux-kernel@...r.kernel.org,
	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Arnd Bergmann <arnd@...db.de>, yrl.pp-manager.tt@...achi.com
Subject: Re: [PATCH 2/2] [BUGFIX] virtio/console: Add pipe_lock/unlock for
 splice_write

On (Fri) 19 Jul 2013 [08:19:32], Yoshihiro YUNOMAE wrote:
> Add pipe_lock/unlock for splice_write to avoid oops by following competition:

> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 8722656..4a28e4c 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -936,6 +936,7 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
>  	 * pipe->nrbufs == 0 means there are no data to transfer,
>  	 * so this returns just 0 for no data.
>  	 */
> +	pipe_lock(pipe);
>  	if (!pipe->nrbufs)
>  		return 0;
>  
> @@ -953,6 +954,7 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
>  	sgl.sg = buf->sg;
>  	sg_init_table(sgl.sg, sgl.size);
>  	ret = __splice_from_pipe(pipe, &sd, pipe_to_sg);
> +	pipe_unlock(pipe);
>  	if (likely(ret > 0))
>  		ret = __send_to_port(port, buf->sg, sgl.n, sgl.len, buf, true);
>  
> 

You're not unlocking in all the error return cases.

		Amit
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