[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>

diff --git a/drivers/staging/tm6000/tm6000-alsa.c b/drivers/staging/tm6000/tm6000-alsa.c
index a99101fef1a39ee3991a3db7752b396b5a18860d..e379e3ec444295a2153fa0821d2925b5522b836e 100644 (file)
--- 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 1ec1bff9b294b76e90af2f0d73890351da524bc2..5d9dcab5c87d88b70a6b671cfc5714252cfef0e6 100644 (file)
--- 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;