Re: [PATCH 2/3] echoaudio: Prevent races in calls to set_audio_format()

[Takashi Iwai <tiwai@suse.de>]

On Tue, 16 Jun 2020 15:17:42 +0200,
Mark Hills wrote:
> 
> The function uses chip->comm_page which needs locking against
> other use at the same time.
> 
> Signed-off-by: Mark Hills <mark@xwax.org>
> ---
>  sound/pci/echoaudio/echoaudio.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
> index 82a49dfd2384..8cf08988959f 100644
> --- a/sound/pci/echoaudio/echoaudio.c
> +++ b/sound/pci/echoaudio/echoaudio.c
> @@ -711,9 +711,22 @@ static int pcm_prepare(struct snd_pcm_substream *substream)
>  
>  	if (snd_BUG_ON(pipe_index >= px_num(chip)))
>  		return -EINVAL;
> -	if (snd_BUG_ON(!is_pipe_allocated(chip, pipe_index)))
> +
> +	/*
> +	 * We passed checks we can do independently; now take
> +	 * exclusive control
> +	 */
> +
> +	spin_lock(&chip->lock);

You need spin_lock_irq() and spin_unlock_irq(), as the prepare
callback in in sleepable context.


thanks,

Takashi