ALSA: rawmidi: Use guard() for locking

We can simplify the code gracefully with new guard() macro and co for
automatic cleanup of locks.

There are a few remaining explicit mutex and spinlock calls, and those
are the places where the temporary unlock/relocking happens -- which
guard() doens't cover well yet.

Only the code refactoring, and no functional changes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240227085306.9764-10-tiwai@suse.de

sound/core/rawmidi.c

@@ -105,13 +105,8 @@ static inline bool __snd_rawmidi_ready(struct snd_rawmidi_runtime *runtime)
 
 static bool snd_rawmidi_ready(struct snd_rawmidi_substream *substream)
 {
-	unsigned long flags;
-	bool ready;
-
-	spin_lock_irqsave(&substream->lock, flags);
-	ready = __snd_rawmidi_ready(substream->runtime);
-	spin_unlock_irqrestore(&substream->lock, flags);
-	return ready;
+	guard(spinlock_irqsave)(&substream->lock);
+	return __snd_rawmidi_ready(substream->runtime);
 }
 
 static inline int snd_rawmidi_ready_append(struct snd_rawmidi_substream *substream,
@@ -238,12 +233,9 @@ static void __reset_runtime_ptrs(struct snd_rawmidi_runtime *runtime,
 static void reset_runtime_ptrs(struct snd_rawmidi_substream *substream,
 			       bool is_input)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	if (substream->opened && substream->runtime)
 		__reset_runtime_ptrs(substream->runtime, is_input);
-	spin_unlock_irqrestore(&substream->lock, flags);
 }
 
 int snd_rawmidi_drop_output(struct snd_rawmidi_substream *substream)
@@ -260,33 +252,29 @@ int snd_rawmidi_drain_output(struct snd_rawmidi_substream *substream)
 	long timeout;
 	struct snd_rawmidi_runtime *runtime;
 
-	spin_lock_irq(&substream->lock);
-	runtime = substream->runtime;
-	if (!substream->opened || !runtime || !runtime->buffer) {
-		err = -EINVAL;
-	} else {
+	scoped_guard(spinlock_irq, &substream->lock) {
+		runtime = substream->runtime;
+		if (!substream->opened || !runtime || !runtime->buffer)
+			return -EINVAL;
 		snd_rawmidi_buffer_ref(runtime);
 		runtime->drain = 1;
 	}
-	spin_unlock_irq(&substream->lock);
-	if (err < 0)
-		return err;
 
 	timeout = wait_event_interruptible_timeout(runtime->sleep,
 				(runtime->avail >= runtime->buffer_size),
 				10*HZ);
 
-	spin_lock_irq(&substream->lock);
-	if (signal_pending(current))
-		err = -ERESTARTSYS;
-	if (runtime->avail < runtime->buffer_size && !timeout) {
-		rmidi_warn(substream->rmidi,
-			   "rawmidi drain error (avail = %li, buffer_size = %li)\n",
-			   (long)runtime->avail, (long)runtime->buffer_size);
-		err = -EIO;
+	scoped_guard(spinlock_irq, &substream->lock) {
+		if (signal_pending(current))
+			err = -ERESTARTSYS;
+		if (runtime->avail < runtime->buffer_size && !timeout) {
+			rmidi_warn(substream->rmidi,
+				   "rawmidi drain error (avail = %li, buffer_size = %li)\n",
+				   (long)runtime->avail, (long)runtime->buffer_size);
+			err = -EIO;
+		}
+		runtime->drain = 0;
 	}
-	runtime->drain = 0;
-	spin_unlock_irq(&substream->lock);
 
 	if (err != -ERESTARTSYS) {
 		/* we need wait a while to make sure that Tx FIFOs are empty */
@@ -297,9 +285,8 @@ int snd_rawmidi_drain_output(struct snd_rawmidi_substream *substream)
 		snd_rawmidi_drop_output(substream);
 	}
 
-	spin_lock_irq(&substream->lock);
-	snd_rawmidi_buffer_unref(runtime);
-	spin_unlock_irq(&substream->lock);
+	scoped_guard(spinlock_irq, &substream->lock)
+		snd_rawmidi_buffer_unref(runtime);
 
 	return err;
 }
@@ -363,14 +350,13 @@ static int open_substream(struct snd_rawmidi *rmidi,
 			snd_rawmidi_runtime_free(substream);
 			return err;
 		}
-		spin_lock_irq(&substream->lock);
+		guard(spinlock_irq)(&substream->lock);
 		substream->opened = 1;
 		substream->active_sensing = 0;
 		if (mode & SNDRV_RAWMIDI_LFLG_APPEND)
 			substream->append = 1;
 		substream->pid = get_pid(task_pid(current));
 		rmidi->streams[substream->stream].substream_opened++;
-		spin_unlock_irq(&substream->lock);
 	}
 	substream->use_count++;
 	return 0;
@@ -433,9 +419,8 @@ int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi, int subdevice,
 	if (!try_module_get(rmidi->card->module))
 		return -ENXIO;
 
-	mutex_lock(&rmidi->open_mutex);
+	guard(mutex)(&rmidi->open_mutex);
 	err = rawmidi_open_priv(rmidi, subdevice, mode, rfile);
-	mutex_unlock(&rmidi->open_mutex);
 	if (err < 0)
 		module_put(rmidi->card->module);
 	return err;
@@ -568,10 +553,10 @@ static void close_substream(struct snd_rawmidi *rmidi,
 		}
 		snd_rawmidi_buffer_ref_sync(substream);
 	}
-	spin_lock_irq(&substream->lock);
-	substream->opened = 0;
-	substream->append = 0;
-	spin_unlock_irq(&substream->lock);
+	scoped_guard(spinlock_irq, &substream->lock) {
+		substream->opened = 0;
+		substream->append = 0;
+	}
 	substream->ops->close(substream);
 	if (substream->runtime->private_free)
 		substream->runtime->private_free(substream);
@@ -586,7 +571,7 @@ static void rawmidi_release_priv(struct snd_rawmidi_file *rfile)
 	struct snd_rawmidi *rmidi;
 
 	rmidi = rfile->rmidi;
-	mutex_lock(&rmidi->open_mutex);
+	guard(mutex)(&rmidi->open_mutex);
 	if (rfile->input) {
 		close_substream(rmidi, rfile->input, 1);
 		rfile->input = NULL;
@@ -596,7 +581,6 @@ static void rawmidi_release_priv(struct snd_rawmidi_file *rfile)
 		rfile->output = NULL;
 	}
 	rfile->rmidi = NULL;
-	mutex_unlock(&rmidi->open_mutex);
 	wake_up(&rmidi->open_wait);
 }
 
@@ -695,12 +679,8 @@ static int __snd_rawmidi_info_select(struct snd_card *card,
 
 int snd_rawmidi_info_select(struct snd_card *card, struct snd_rawmidi_info *info)
 {
-	int ret;
-
-	mutex_lock(&register_mutex);
-	ret = __snd_rawmidi_info_select(card, info);
-	mutex_unlock(&register_mutex);
-	return ret;
+	guard(mutex)(&register_mutex);
+	return __snd_rawmidi_info_select(card, info);
 }
 EXPORT_SYMBOL(snd_rawmidi_info_select);
 
@@ -744,9 +724,8 @@ static int resize_runtime_buffer(struct snd_rawmidi_substream *substream,
 		newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);
 		if (!newbuf)
 			return -ENOMEM;
-		spin_lock_irq(&substream->lock);
+		guard(spinlock_irq)(&substream->lock);
 		if (runtime->buffer_ref) {
-			spin_unlock_irq(&substream->lock);
 			kvfree(newbuf);
 			return -EBUSY;
 		}
@@ -754,7 +733,6 @@ static int resize_runtime_buffer(struct snd_rawmidi_substream *substream,
 		runtime->buffer = newbuf;
 		runtime->buffer_size = params->buffer_size;
 		__reset_runtime_ptrs(runtime, is_input);
-		spin_unlock_irq(&substream->lock);
 		kvfree(oldbuf);
 	}
 	runtime->avail_min = params->avail_min;
@@ -767,15 +745,12 @@ int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream,
 	int err;
 
 	snd_rawmidi_drain_output(substream);
-	mutex_lock(&substream->rmidi->open_mutex);
+	guard(mutex)(&substream->rmidi->open_mutex);
 	if (substream->append && substream->use_count > 1)
-		err = -EBUSY;
-	else
-		err = resize_runtime_buffer(substream, params, false);
-
+		return -EBUSY;
+	err = resize_runtime_buffer(substream, params, false);
 	if (!err)
 		substream->active_sensing = !params->no_active_sensing;
-	mutex_unlock(&substream->rmidi->open_mutex);
 	return err;
 }
 EXPORT_SYMBOL(snd_rawmidi_output_params);
@@ -788,7 +763,7 @@ int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
 	int err;
 
 	snd_rawmidi_drain_input(substream);
-	mutex_lock(&substream->rmidi->open_mutex);
+	guard(mutex)(&substream->rmidi->open_mutex);
 	if (framing == SNDRV_RAWMIDI_MODE_FRAMING_NONE && clock_type != SNDRV_RAWMIDI_MODE_CLOCK_NONE)
 		err = -EINVAL;
 	else if (clock_type > SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW)
@@ -802,7 +777,6 @@ int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
 		substream->framing = framing;
 		substream->clock_type = clock_type;
 	}
-	mutex_unlock(&substream->rmidi->open_mutex);
 	return 0;
 }
 EXPORT_SYMBOL(snd_rawmidi_input_params);
@@ -814,9 +788,8 @@ static int snd_rawmidi_output_status(struct snd_rawmidi_substream *substream,
 
 	memset(status, 0, sizeof(*status));
 	status->stream = SNDRV_RAWMIDI_STREAM_OUTPUT;
-	spin_lock_irq(&substream->lock);
+	guard(spinlock_irq)(&substream->lock);
 	status->avail = runtime->avail;
-	spin_unlock_irq(&substream->lock);
 	return 0;
 }
 
@@ -827,11 +800,10 @@ static int snd_rawmidi_input_status(struct snd_rawmidi_substream *substream,
 
 	memset(status, 0, sizeof(*status));
 	status->stream = SNDRV_RAWMIDI_STREAM_INPUT;
-	spin_lock_irq(&substream->lock);
+	guard(spinlock_irq)(&substream->lock);
 	status->avail = runtime->avail;
 	status->xruns = runtime->xruns;
 	runtime->xruns = 0;
-	spin_unlock_irq(&substream->lock);
 	return 0;
 }
 
@@ -1025,19 +997,19 @@ static int snd_rawmidi_next_device(struct snd_card *card, int __user *argp,
 		return -EFAULT;
 	if (device >= SNDRV_RAWMIDI_DEVICES) /* next device is -1 */
 		device = SNDRV_RAWMIDI_DEVICES - 1;
-	mutex_lock(&register_mutex);
-	device = device < 0 ? 0 : device + 1;
-	for (; device < SNDRV_RAWMIDI_DEVICES; device++) {
-		rmidi = snd_rawmidi_search(card, device);
-		if (!rmidi)
-			continue;
-		is_ump = rawmidi_is_ump(rmidi);
-		if (find_ump == is_ump)
-			break;
+	scoped_guard(mutex, &register_mutex) {
+		device = device < 0 ? 0 : device + 1;
+		for (; device < SNDRV_RAWMIDI_DEVICES; device++) {
+			rmidi = snd_rawmidi_search(card, device);
+			if (!rmidi)
+				continue;
+			is_ump = rawmidi_is_ump(rmidi);
+			if (find_ump == is_ump)
+				break;
+		}
+		if (device == SNDRV_RAWMIDI_DEVICES)
+			device = -1;
 	}
-	if (device == SNDRV_RAWMIDI_DEVICES)
-		device = -1;
-	mutex_unlock(&register_mutex);
 	if (put_user(device, argp))
 		return -EFAULT;
 	return 0;
@@ -1050,18 +1022,16 @@ static int snd_rawmidi_call_ump_ioctl(struct snd_card *card, int cmd,
 {
 	struct snd_ump_endpoint_info __user *info = argp;
 	struct snd_rawmidi *rmidi;
-	int device, ret;
+	int device;
 
 	if (get_user(device, &info->device))
 		return -EFAULT;
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	rmidi = snd_rawmidi_search(card, device);
 	if (rmidi && rmidi->ops && rmidi->ops->ioctl)
-		ret = rmidi->ops->ioctl(rmidi, cmd, argp);
+		return rmidi->ops->ioctl(rmidi, cmd, argp);
 	else
-		ret = -ENXIO;
-	mutex_unlock(&register_mutex);
-	return ret;
+		return -ENXIO;
 }
 #endif
 
@@ -1168,27 +1138,23 @@ static struct timespec64 get_framing_tstamp(struct snd_rawmidi_substream *substr
 int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
 			const unsigned char *buffer, int count)
 {
-	unsigned long flags;
 	struct timespec64 ts64 = get_framing_tstamp(substream);
 	int result = 0, count1;
 	struct snd_rawmidi_runtime *runtime;
 
-	spin_lock_irqsave(&substream->lock, flags);
-	if (!substream->opened) {
-		result = -EBADFD;
-		goto unlock;
-	}
+	guard(spinlock_irqsave)(&substream->lock);
+	if (!substream->opened)
+		return -EBADFD;
 	runtime = substream->runtime;
 	if (!runtime || !runtime->buffer) {
 		rmidi_dbg(substream->rmidi,
 			  "snd_rawmidi_receive: input is not active!!!\n");
-		result = -EINVAL;
-		goto unlock;
+		return -EINVAL;
 	}
 
 	count = get_aligned_size(runtime, count);
 	if (!count)
-		goto unlock;
+		return result;
 
 	if (substream->framing == SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP) {
 		result = receive_with_tstamp_framing(substream, buffer, count, &ts64);
@@ -1211,7 +1177,7 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
 			count1 = runtime->buffer_size - runtime->avail;
 		count1 = get_aligned_size(runtime, count1);
 		if (!count1)
-			goto unlock;
+			return result;
 		memcpy(runtime->buffer + runtime->hw_ptr, buffer, count1);
 		runtime->hw_ptr += count1;
 		runtime->hw_ptr %= runtime->buffer_size;
@@ -1239,8 +1205,6 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
 		else if (__snd_rawmidi_ready(runtime))
 			wake_up(&runtime->sleep);
 	}
- unlock:
-	spin_unlock_irqrestore(&substream->lock, flags);
 	return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_receive);
@@ -1362,20 +1326,15 @@ static ssize_t snd_rawmidi_read(struct file *file, char __user *buf, size_t coun
 int snd_rawmidi_transmit_empty(struct snd_rawmidi_substream *substream)
 {
 	struct snd_rawmidi_runtime *runtime;
-	int result;
-	unsigned long flags;
 
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	runtime = substream->runtime;
 	if (!substream->opened || !runtime || !runtime->buffer) {
 		rmidi_dbg(substream->rmidi,
 			  "snd_rawmidi_transmit_empty: output is not active!!!\n");
-		result = 1;
-	} else {
-		result = runtime->avail >= runtime->buffer_size;
+		return 1;
 	}
-	spin_unlock_irqrestore(&substream->lock, flags);
-	return result;
+	return (runtime->avail >= runtime->buffer_size);
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_empty);
 
@@ -1449,16 +1408,10 @@ static int __snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream,
 int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream,
 			      unsigned char *buffer, int count)
 {
-	int result;
-	unsigned long flags;
-
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	if (!substream->opened || !substream->runtime)
-		result = -EBADFD;
-	else
-		result = __snd_rawmidi_transmit_peek(substream, buffer, count);
-	spin_unlock_irqrestore(&substream->lock, flags);
-	return result;
+		return -EBADFD;
+	return __snd_rawmidi_transmit_peek(substream, buffer, count);
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_peek);
 
@@ -1505,16 +1458,10 @@ static int __snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream,
  */
 int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count)
 {
-	int result;
-	unsigned long flags;
-
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	if (!substream->opened || !substream->runtime)
-		result = -EBADFD;
-	else
-		result = __snd_rawmidi_transmit_ack(substream, count);
-	spin_unlock_irqrestore(&substream->lock, flags);
-	return result;
+		return -EBADFD;
+	return __snd_rawmidi_transmit_ack(substream, count);
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_ack);
 
@@ -1531,21 +1478,13 @@ EXPORT_SYMBOL(snd_rawmidi_transmit_ack);
 int snd_rawmidi_transmit(struct snd_rawmidi_substream *substream,
 			 unsigned char *buffer, int count)
 {
-	int result;
-	unsigned long flags;
-
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	if (!substream->opened)
-		result = -EBADFD;
-	else {
-		count = __snd_rawmidi_transmit_peek(substream, buffer, count);
-		if (count <= 0)
-			result = count;
-		else
-			result = __snd_rawmidi_transmit_ack(substream, count);
-	}
-	spin_unlock_irqrestore(&substream->lock, flags);
-	return result;
+		return -EBADFD;
+	count = __snd_rawmidi_transmit_peek(substream, buffer, count);
+	if (count <= 0)
+		return count;
+	return __snd_rawmidi_transmit_ack(substream, count);
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit);
 
@@ -1558,17 +1497,15 @@ EXPORT_SYMBOL(snd_rawmidi_transmit);
 int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream)
 {
 	struct snd_rawmidi_runtime *runtime;
-	unsigned long flags;
 	int count = 0;
 
-	spin_lock_irqsave(&substream->lock, flags);
+	guard(spinlock_irqsave)(&substream->lock);
 	runtime = substream->runtime;
 	if (substream->opened && runtime &&
 	    runtime->avail < runtime->buffer_size) {
 		count = runtime->buffer_size - runtime->avail;
 		__snd_rawmidi_transmit_ack(substream, count);
 	}
-	spin_unlock_irqrestore(&substream->lock, flags);
 	return count;
 }
 EXPORT_SYMBOL(snd_rawmidi_proceed);
@@ -1772,7 +1709,7 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
 			    rawmidi_is_ump(rmidi) ? "UMP" : "Legacy");
 	if (rmidi->ops && rmidi->ops->proc_read)
 		rmidi->ops->proc_read(entry, buffer);
-	mutex_lock(&rmidi->open_mutex);
+	guard(mutex)(&rmidi->open_mutex);
 	if (rmidi->info_flags & SNDRV_RAWMIDI_INFO_OUTPUT) {
 		list_for_each_entry(substream,
 				    &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams,
@@ -1787,10 +1724,10 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
 				    "  Owner PID    : %d\n",
 				    pid_vnr(substream->pid));
 				runtime = substream->runtime;
-				spin_lock_irq(&substream->lock);
-				buffer_size = runtime->buffer_size;
-				avail = runtime->avail;
-				spin_unlock_irq(&substream->lock);
+				scoped_guard(spinlock_irq, &substream->lock) {
+					buffer_size = runtime->buffer_size;
+					avail = runtime->avail;
+				}
 				snd_iprintf(buffer,
 				    "  Mode         : %s\n"
 				    "  Buffer size  : %lu\n"
@@ -1814,11 +1751,11 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
 					    "  Owner PID    : %d\n",
 					    pid_vnr(substream->pid));
 				runtime = substream->runtime;
-				spin_lock_irq(&substream->lock);
-				buffer_size = runtime->buffer_size;
-				avail = runtime->avail;
-				xruns = runtime->xruns;
-				spin_unlock_irq(&substream->lock);
+				scoped_guard(spinlock_irq, &substream->lock) {
+					buffer_size = runtime->buffer_size;
+					avail = runtime->avail;
+					xruns = runtime->xruns;
+				}
 				snd_iprintf(buffer,
 					    "  Buffer size  : %lu\n"
 					    "  Avail        : %lu\n"
@@ -1835,7 +1772,6 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
 			}
 		}
 	}
-	mutex_unlock(&rmidi->open_mutex);
 }
 
 /*
@@ -2024,12 +1960,12 @@ static int snd_rawmidi_dev_register(struct snd_device *device)
 	if (rmidi->device >= SNDRV_RAWMIDI_DEVICES)
 		return -ENOMEM;
 	err = 0;
-	mutex_lock(&register_mutex);
-	if (snd_rawmidi_search(rmidi->card, rmidi->device))
-		err = -EBUSY;
-	else
-		list_add_tail(&rmidi->list, &snd_rawmidi_devices);
-	mutex_unlock(&register_mutex);
+	scoped_guard(mutex, &register_mutex) {
+		if (snd_rawmidi_search(rmidi->card, rmidi->device))
+			err = -EBUSY;
+		else
+			list_add_tail(&rmidi->list, &snd_rawmidi_devices);
+	}
 	if (err < 0)
 		return err;
 
@@ -2102,9 +2038,8 @@ static int snd_rawmidi_dev_register(struct snd_device *device)
  error_unregister:
 	snd_unregister_device(rmidi->dev);
  error:
-	mutex_lock(&register_mutex);
-	list_del(&rmidi->list);
-	mutex_unlock(&register_mutex);
+	scoped_guard(mutex, &register_mutex)
+		list_del(&rmidi->list);
 	return err;
 }
 
@@ -2113,8 +2048,8 @@ static int snd_rawmidi_dev_disconnect(struct snd_device *device)
 	struct snd_rawmidi *rmidi = device->device_data;
 	int dir;
 
-	mutex_lock(&register_mutex);
-	mutex_lock(&rmidi->open_mutex);
+	guard(mutex)(&register_mutex);
+	guard(mutex)(&rmidi->open_mutex);
 	wake_up(&rmidi->open_wait);
 	list_del_init(&rmidi->list);
 	for (dir = 0; dir < 2; dir++) {
@@ -2140,8 +2075,6 @@ static int snd_rawmidi_dev_disconnect(struct snd_device *device)
 	}
 #endif /* CONFIG_SND_OSSEMUL */
 	snd_unregister_device(rmidi->dev);
-	mutex_unlock(&rmidi->open_mutex);
-	mutex_unlock(&register_mutex);
 	return 0;
 }