[ALSA] sound/drivers/dummy.c: fix negative snd_pcm_format_width() check

bps is unsigned, a negative snd_pcm_format_width() return value is not noticed

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 5 insertions, 4 deletions

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index 83ac4980c5fb..4e4c69e6cb4c 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -230,13 +230,14 @@ static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream)
 {
         struct snd_pcm_runtime *runtime = substream->runtime;
         struct snd_dummy_pcm *dpcm = runtime->private_data;
-        unsigned int bps;
+        int bps;
+
+        bps = snd_pcm_format_width(runtime->format) * runtime->rate *
+                runtime->channels / 8;
 
-        bps = runtime->rate * runtime->channels;
-        bps *= snd_pcm_format_width(runtime->format);
-        bps /= 8;
         if (bps <= 0)
                 return -EINVAL;
+
         dpcm->pcm_bps = bps;
         dpcm->pcm_hz = HZ;
         dpcm->pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);