ALSA: aloop: Fix random zeros in capture data when using jiffies timer

commit 3e48940abee88b8dbbeeaf8a07e7b2b6be1271b3 upstream.

In loopback_jiffies_timer_pos_update(), we are getting jiffies twice.
First time for playback, second time for capture. Jiffies can be updated
between these two calls and if the capture jiffies is larger, extra zeros
will be filled in the capture buffer.

Change to get jiffies once and use it for both playback and capture.

Signed-off-by: Pattara Teerapong <pteerapong@chromium.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220901144036.4049060-1-pteerapong@chromium.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index 2c5f7e905ab8fe6cfcf934967b001ad5c86f4ad5..fb45a32d99cd9cd73e0b88d982e53f3865c364f8 100644 (file)
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -606,17 +606,18 @@ static unsigned int loopback_jiffies_timer_pos_update
                        cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
        struct loopback_pcm *dpcm_capt =
                        cable->streams[SNDRV_PCM_STREAM_CAPTURE];
-       unsigned long delta_play = 0, delta_capt = 0;
+       unsigned long delta_play = 0, delta_capt = 0, cur_jiffies;
        unsigned int running, count1, count2;
 
+       cur_jiffies = jiffies;
        running = cable->running ^ cable->pause;
        if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
-               delta_play = jiffies - dpcm_play->last_jiffies;
+               delta_play = cur_jiffies - dpcm_play->last_jiffies;
                dpcm_play->last_jiffies += delta_play;
        }
 
        if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
-               delta_capt = jiffies - dpcm_capt->last_jiffies;
+               delta_capt = cur_jiffies - dpcm_capt->last_jiffies;
                dpcm_capt->last_jiffies += delta_capt;
        }