ALSA: usx2y: Don't peep the card internal object

Avoid traversing the device object list of the card instance just for
checking the PCM streams.  The driver's private object already
contains the array of substream pointers, so it can be simply looked
through.  The card internal may be restructured in future, thus better
not to rely on it.

Also, this fixes the possible deadlocks in PCM mutex.  Instead of
taking multiple PCM mutexes, just take the common mutex in all
places.  Along with it, rename prepare_mutex as pcm_mutex.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/usx2y/usbusx2y.c

@@ -353,7 +353,7 @@ static int usX2Y_create_card(struct usb_device *device,
 	card->private_free = snd_usX2Y_card_private_free;
 	usX2Y(card)->dev = device;
 	init_waitqueue_head(&usX2Y(card)->prepare_wait_queue);
-	mutex_init(&usX2Y(card)->prepare_mutex);
+	mutex_init(&usX2Y(card)->pcm_mutex);
 	INIT_LIST_HEAD(&usX2Y(card)->midi_list);
 	strcpy(card->driver, "USB "NAME_ALLCAPS"");
 	sprintf(card->shortname, "TASCAM "NAME_ALLCAPS"");

sound/usb/usx2y/usbusx2y.h

@@ -36,7 +36,7 @@ struct usX2Ydev {
 	unsigned int		rate,
 				format;
 	int			chip_status;
-	struct mutex		prepare_mutex;
+	struct mutex		pcm_mutex;
 	struct us428ctls_sharedmem	*us428ctls_sharedmem;
 	int			wait_iso_frame;
 	wait_queue_head_t	us428ctls_wait_queue_head;

sound/usb/usx2y/usbusx2yaudio.c

@@ -752,36 +752,44 @@ static int snd_usX2Y_pcm_hw_params(struct snd_pcm_substream *substream,
 	unsigned int		rate = params_rate(hw_params);
 	snd_pcm_format_t	format = params_format(hw_params);
 	struct snd_card *card = substream->pstr->pcm->card;
-	struct list_head *list;
+	struct usX2Ydev	*dev = usX2Y(card);
+	int i;
 
+	mutex_lock(&usX2Y(card)->pcm_mutex);
 	snd_printdd("snd_usX2Y_hw_params(%p, %p)\n", substream, hw_params);
-	// all pcm substreams off one usX2Y have to operate at the same rate & format
-	list_for_each(list, &card->devices) {
-		struct snd_device *dev;
-		struct snd_pcm *pcm;
-		int s;
-		dev = snd_device(list);
-		if (dev->type != SNDRV_DEV_PCM)
+	/* all pcm substreams off one usX2Y have to operate at the same
+	 * rate & format
+	 */
+	for (i = 0; i < dev->pcm_devs * 2; i++) {
+		struct snd_usX2Y_substream *subs = dev->subs[i];
+		struct snd_pcm_substream *test_substream;
+
+		if (!subs)
+			continue;
+		test_substream = subs->pcm_substream;
+		if (!test_substream || test_substream == substream ||
+		    !test_substream->runtime)
 			continue;
-		pcm = dev->device_data;
-		for (s = 0; s < 2; ++s) {
-			struct snd_pcm_substream *test_substream;
-			test_substream = pcm->streams[s].substream;
-			if (test_substream && test_substream != substream  &&
-			    test_substream->runtime &&
-			    ((test_substream->runtime->format &&
-			      test_substream->runtime->format != format) ||
-			     (test_substream->runtime->rate &&
-			      test_substream->runtime->rate != rate)))
-				return -EINVAL;
+		if ((test_substream->runtime->format &&
+		     test_substream->runtime->format != format) ||
+		    (test_substream->runtime->rate &&
+		     test_substream->runtime->rate != rate)) {
+			err = -EINVAL;
+			goto error;
 		}
 	}
-	if (0 > (err = snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params)))) {
+
+	err = snd_pcm_lib_malloc_pages(substream,
+				       params_buffer_bytes(hw_params));
+	if (err < 0) {
 		snd_printk(KERN_ERR "snd_pcm_lib_malloc_pages(%p, %i) returned %i\n",
 			   substream, params_buffer_bytes(hw_params), err);
-		return err;
+		goto error;
 	}
-	return 0;
+
+ error:
+	mutex_unlock(&usX2Y(card)->pcm_mutex);
+	return err;
 }
 
 /*
@@ -791,7 +799,7 @@ static int snd_usX2Y_pcm_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_usX2Y_substream *subs = runtime->private_data;
-	mutex_lock(&subs->usX2Y->prepare_mutex);
+	mutex_lock(&subs->usX2Y->pcm_mutex);
 	snd_printdd("snd_usX2Y_hw_free(%p)\n", substream);
 
 	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
@@ -812,7 +820,7 @@ static int snd_usX2Y_pcm_hw_free(struct snd_pcm_substream *substream)
 			usX2Y_urbs_release(subs);
 		}
 	}
-	mutex_unlock(&subs->usX2Y->prepare_mutex);
+	mutex_unlock(&subs->usX2Y->pcm_mutex);
 	return snd_pcm_lib_free_pages(substream);
 }
 /*
@@ -829,7 +837,7 @@ static int snd_usX2Y_pcm_prepare(struct snd_pcm_substream *substream)
 	int err = 0;
 	snd_printdd("snd_usX2Y_pcm_prepare(%p)\n", substream);
 
-	mutex_lock(&usX2Y->prepare_mutex);
+	mutex_lock(&usX2Y->pcm_mutex);
 	usX2Y_subs_prepare(subs);
 // Start hardware streams
 // SyncStream first....
@@ -849,7 +857,7 @@ static int snd_usX2Y_pcm_prepare(struct snd_pcm_substream *substream)
 		err = usX2Y_urbs_start(subs);
 
  up_prepare_mutex:
-	mutex_unlock(&usX2Y->prepare_mutex);
+	mutex_unlock(&usX2Y->pcm_mutex);
 	return err;
 }
 

sound/usb/usx2y/usx2yhwdeppcm.c

@@ -358,7 +358,7 @@ static int snd_usX2Y_usbpcm_hw_free(struct snd_pcm_substream *substream)
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_usX2Y_substream *subs = runtime->private_data,
 		*cap_subs2 = subs->usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE + 2];
-	mutex_lock(&subs->usX2Y->prepare_mutex);
+	mutex_lock(&subs->usX2Y->pcm_mutex);
 	snd_printdd("snd_usX2Y_usbpcm_hw_free(%p)\n", substream);
 
 	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
@@ -387,7 +387,7 @@ static int snd_usX2Y_usbpcm_hw_free(struct snd_pcm_substream *substream)
 				usX2Y_usbpcm_urbs_release(cap_subs2);
 		}
 	}
-	mutex_unlock(&subs->usX2Y->prepare_mutex);
+	mutex_unlock(&subs->usX2Y->pcm_mutex);
 	return snd_pcm_lib_free_pages(substream);
 }
 
@@ -493,7 +493,7 @@ static int snd_usX2Y_usbpcm_prepare(struct snd_pcm_substream *substream)
 		memset(usX2Y->hwdep_pcm_shm, 0, sizeof(struct snd_usX2Y_hwdep_pcm_shm));
 	}
 
-	mutex_lock(&usX2Y->prepare_mutex);
+	mutex_lock(&usX2Y->pcm_mutex);
 	usX2Y_subs_prepare(subs);
 // Start hardware streams
 // SyncStream first....
@@ -534,7 +534,7 @@ static int snd_usX2Y_usbpcm_prepare(struct snd_pcm_substream *substream)
 		usX2Y->hwdep_pcm_shm->capture_iso_start = -1;
 
  up_prepare_mutex:
-	mutex_unlock(&usX2Y->prepare_mutex);
+	mutex_unlock(&usX2Y->pcm_mutex);
 	return err;
 }
 
@@ -600,59 +600,30 @@ static struct snd_pcm_ops snd_usX2Y_usbpcm_ops =
 };
 
 
-static int usX2Y_pcms_lock_check(struct snd_card *card)
+static int usX2Y_pcms_busy_check(struct snd_card *card)
 {
-	struct list_head *list;
-	struct snd_device *dev;
-	struct snd_pcm *pcm;
-	int err = 0;
-	list_for_each(list, &card->devices) {
-		dev = snd_device(list);
-		if (dev->type != SNDRV_DEV_PCM)
-			continue;
-		pcm = dev->device_data;
-		mutex_lock(&pcm->open_mutex);
-	}
-	list_for_each(list, &card->devices) {
-		int s;
-		dev = snd_device(list);
-		if (dev->type != SNDRV_DEV_PCM)
-			continue;
-		pcm = dev->device_data;
-		for (s = 0; s < 2; ++s) {
-			struct snd_pcm_substream *substream;
-			substream = pcm->streams[s].substream;
-			if (substream && SUBSTREAM_BUSY(substream))
-				err = -EBUSY;
-		}
-	}
-	return err;
-}
-
+	struct usX2Ydev	*dev = usX2Y(card);
+	int i;
 
-static void usX2Y_pcms_unlock(struct snd_card *card)
-{
-	struct list_head *list;
-	struct snd_device *dev;
-	struct snd_pcm *pcm;
-	list_for_each(list, &card->devices) {
-		dev = snd_device(list);
-		if (dev->type != SNDRV_DEV_PCM)
-			continue;
-		pcm = dev->device_data;
-		mutex_unlock(&pcm->open_mutex);
+	for (i = 0; i < dev->pcm_devs * 2; i++) {
+		struct snd_usX2Y_substream *subs = dev->subs[i];
+		if (subs && subs->pcm_substream &&
+		    SUBSTREAM_BUSY(subs->pcm_substream))
+			return -EBUSY;
 	}
+	return 0;
 }
 
-
 static int snd_usX2Y_hwdep_pcm_open(struct snd_hwdep *hw, struct file *file)
 {
-	// we need to be the first 
 	struct snd_card *card = hw->card;
-	int err = usX2Y_pcms_lock_check(card);
-	if (0 == err)
+	int err;
+
+	mutex_lock(&usX2Y(card)->pcm_mutex);
+	err = usX2Y_pcms_busy_check(card);
+	if (!err)
 		usX2Y(card)->chip_status |= USX2Y_STAT_CHIP_MMAP_PCM_URBS;
-	usX2Y_pcms_unlock(card);
+	mutex_unlock(&usX2Y(card)->pcm_mutex);
 	return err;
 }
 
@@ -660,10 +631,13 @@ static int snd_usX2Y_hwdep_pcm_open(struct snd_hwdep *hw, struct file *file)
 static int snd_usX2Y_hwdep_pcm_release(struct snd_hwdep *hw, struct file *file)
 {
 	struct snd_card *card = hw->card;
-	int err = usX2Y_pcms_lock_check(card);
-	if (0 == err)
+	int err;
+
+	mutex_lock(&usX2Y(card)->pcm_mutex);
+	err = usX2Y_pcms_busy_check(card);
+	if (!err)
 		usX2Y(hw->card)->chip_status &= ~USX2Y_STAT_CHIP_MMAP_PCM_URBS;
-	usX2Y_pcms_unlock(card);
+	mutex_unlock(&usX2Y(card)->pcm_mutex);
 	return err;
 }