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SubjectRe: [PATCH 1/2] ALSA: firewire-tascam: Fix infinite loop in snd_tscm_stream_get_rate()
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Hi,

On May 15 2017 17:19, Geert Uytterhoeven wrote:
> Obviously the intention was to put a limit on the maximum number of
> operations. However, for this to work, the check should be
> "&& trials++ < 5", not "|| trials++ < 5".
>
> Fixes: 35efa5c489de63a9 ("ALSA: firewire-tascam: add streaming functionality")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> Compile-tested only.
>
> Triggered by a false-positive warning from gcc-4.1.2:
>
> warning: ‘err’ may be used uninitialized in this function
> ---
> sound/firewire/tascam/tascam-stream.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/firewire/tascam/tascam-stream.c b/sound/firewire/tascam/tascam-stream.c
> index f1657a4e0621ef49..e433b92ac6904db5 100644
> --- a/sound/firewire/tascam/tascam-stream.c
> +++ b/sound/firewire/tascam/tascam-stream.c
> @@ -84,7 +84,7 @@ int snd_tscm_stream_get_rate(struct snd_tscm *tscm, unsigned int *rate)
> unsigned int trials = 0;
> int err;
>
> - while (data == 0x0 || trials++ < 5) {
> + while (data == 0x0 && trials++ < 5) {
> err = get_clock(tscm, &data);
> if (err < 0)
> return err;

Yep. It looks a bug.

...However, removal of the bug causes issue that the driver fails to
start a pair of capture/playback PCM substream when application requests
them mostly the same time, like jackd process.

I think I did apply the bug as a makeshift workaround, then forgot
itself when developing the driver... I'd like to have a bit time for
further investigation, then post my fix in this development period.

Please let me keep this patch pending.


Thanks

Takashi Sakamoto

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