[media] tm6000-alsa: fix some locking issues

Those locking issues affect tvtime, causing a kernel oops/panic, due to
a race condition.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 40 insertions, 9 deletions

diff --git a/drivers/staging/tm6000/tm6000-alsa.c b/drivers/staging/tm6000/tm6000-alsa.c
index a99101fef1a3..e379e3ec4442 100644
--- a/drivers/staging/tm6000/tm6000-alsa.c
+++ b/drivers/staging/tm6000/tm6000-alsa.c
@@ -201,6 +201,14 @@ _error:
  */
 static int snd_tm6000_close(struct snd_pcm_substream *substream)
 {
+        struct snd_tm6000_card *chip = snd_pcm_substream_chip(substream);
+        struct tm6000_core *core = chip->core;
+
+        if (atomic_read(&core->stream_started) > 0) {
+                atomic_set(&core->stream_started, 0);
+                schedule_work(&core->wq_trigger);
+        }
+
         return 0;
 }
 
@@ -213,6 +221,9 @@ static int tm6000_fillbuf(struct tm6000_core *core, char *buf, int size)
         unsigned int stride, buf_pos;
         int length;
 
+        if (atomic_read(&core->stream_started) == 0)
+                return 0;
+
         if (!size || !substream) {
                 dprintk(1, "substream was NULL\n");
                 return -EINVAL;
@@ -298,8 +309,12 @@ static int snd_tm6000_hw_params(struct snd_pcm_substream *substream,
 static int snd_tm6000_hw_free(struct snd_pcm_substream *substream)
 {
         struct snd_tm6000_card *chip = snd_pcm_substream_chip(substream);
+        struct tm6000_core *core = chip->core;
 
-        _tm6000_stop_audio_dma(chip);
+        if (atomic_read(&core->stream_started) > 0) {
+                atomic_set(&core->stream_started, 0);
+                schedule_work(&core->wq_trigger);
+        }
 
         return 0;
 }
@@ -321,30 +336,42 @@ static int snd_tm6000_prepare(struct snd_pcm_substream *substream)
 /*
  * trigger callback
  */
+static void audio_trigger(struct work_struct *work)
+{
+        struct tm6000_core *core = container_of(work, struct tm6000_core,
+                                                wq_trigger);
+        struct snd_tm6000_card *chip = core->adev;
+
+        if (atomic_read(&core->stream_started)) {
+                dprintk(1, "starting capture");
+                _tm6000_start_audio_dma(chip);
+        } else {
+                dprintk(1, "stopping capture");
+                _tm6000_stop_audio_dma(chip);
+        }
+}
+
 static int snd_tm6000_card_trigger(struct snd_pcm_substream *substream, int cmd)
 {
         struct snd_tm6000_card *chip = snd_pcm_substream_chip(substream);
-        int err;
-
-        spin_lock(&chip->reg_lock);
+        struct tm6000_core *core = chip->core;
+        int err = 0;
 
         switch (cmd) {
         case SNDRV_PCM_TRIGGER_START:
-                err = _tm6000_start_audio_dma(chip);
+                atomic_set(&core->stream_started, 1);
                 break;
         case SNDRV_PCM_TRIGGER_STOP:
-                err = _tm6000_stop_audio_dma(chip);
+                atomic_set(&core->stream_started, 0);
                 break;
         default:
                 err = -EINVAL;
                 break;
         }
-
-        spin_unlock(&chip->reg_lock);
+        schedule_work(&core->wq_trigger);
 
         return err;
 }
-
 /*
  * pointer callback
  */
@@ -437,6 +464,7 @@ int tm6000_audio_init(struct tm6000_core *dev)
 
         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_tm6000_pcm_ops);
 
+        INIT_WORK(&dev->wq_trigger, audio_trigger);
         rc = snd_card_register(card);
         if (rc < 0)
                 goto error;
diff --git a/drivers/staging/tm6000/tm6000.h b/drivers/staging/tm6000/tm6000.h
index 1ec1bff9b294..5d9dcab5c87d 100644
--- a/drivers/staging/tm6000/tm6000.h
+++ b/drivers/staging/tm6000/tm6000.h
@@ -205,6 +205,9 @@ struct tm6000_core {
 
         /* audio support */
         struct snd_tm6000_card          *adev;
+        struct work_struct              wq_trigger;   /* Trigger to start/stop audio for alsa module */
+        atomic_t                        stream_started;  /* stream should be running if true */
+
 
         struct tm6000_IR                *ir;