ALSA: info: Use guard() for locking

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

Only the code refactoring, and no functional changes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240227085306.9764-7-tiwai@suse.de

sound/core/info.c

@@ -105,17 +105,15 @@ static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
 {
 	struct snd_info_private_data *data;
 	struct snd_info_entry *entry;
-	loff_t ret = -EINVAL, size;
+	loff_t size;
 
 	data = file->private_data;
 	entry = data->entry;
-	mutex_lock(&entry->access);
-	if (entry->c.ops->llseek) {
-		ret = entry->c.ops->llseek(entry,
+	guard(mutex)(&entry->access);
+	if (entry->c.ops->llseek)
+		return entry->c.ops->llseek(entry,
 					    data->file_private_data,
 					    file, offset, orig);
-		goto out;
-	}
 
 	size = entry->size;
 	switch (orig) {
@@ -126,21 +124,18 @@ static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
 		break;
 	case SEEK_END:
 		if (!size)
-			goto out;
+			return -EINVAL;
 		offset += size;
 		break;
 	default:
-		goto out;
+		return -EINVAL;
 	}
 	if (offset < 0)
-		goto out;
+		return -EINVAL;
 	if (size && offset > size)
 		offset = size;
 	file->f_pos = offset;
-	ret = offset;
- out:
-	mutex_unlock(&entry->access);
-	return ret;
+	return offset;
 }
 
 static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
@@ -238,10 +233,10 @@ static int snd_info_entry_open(struct inode *inode, struct file *file)
 	struct snd_info_private_data *data;
 	int mode, err;
 
-	mutex_lock(&info_mutex);
+	guard(mutex)(&info_mutex);
 	err = alloc_info_private(entry, &data);
 	if (err < 0)
-		goto unlock;
+		return err;
 
 	mode = file->f_flags & O_ACCMODE;
 	if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
@@ -257,14 +252,11 @@ static int snd_info_entry_open(struct inode *inode, struct file *file)
 	}
 
 	file->private_data = data;
-	mutex_unlock(&info_mutex);
 	return 0;
 
  error:
 	kfree(data);
 	module_put(entry->module);
- unlock:
-	mutex_unlock(&info_mutex);
 	return err;
 }
 
@@ -306,7 +298,6 @@ static ssize_t snd_info_text_entry_write(struct file *file,
 	struct snd_info_buffer *buf;
 	loff_t pos;
 	size_t next;
-	int err = 0;
 
 	if (!entry->c.text.write)
 		return -EIO;
@@ -317,34 +308,24 @@ static ssize_t snd_info_text_entry_write(struct file *file,
 	/* don't handle too large text inputs */
 	if (next > 16 * 1024)
 		return -EIO;
-	mutex_lock(&entry->access);
+	guard(mutex)(&entry->access);
 	buf = data->wbuffer;
 	if (!buf) {
 		data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
-		if (!buf) {
-			err = -ENOMEM;
-			goto error;
-		}
+		if (!buf)
+			return -ENOMEM;
 	}
 	if (next > buf->len) {
 		char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
-		if (!nbuf) {
-			err = -ENOMEM;
-			goto error;
-		}
+		if (!nbuf)
+			return -ENOMEM;
 		kvfree(buf->buffer);
 		buf->buffer = nbuf;
 		buf->len = PAGE_ALIGN(next);
 	}
-	if (copy_from_user(buf->buffer + pos, buffer, count)) {
-		err = -EFAULT;
-		goto error;
-	}
+	if (copy_from_user(buf->buffer + pos, buffer, count))
+		return -EFAULT;
 	buf->size = next;
- error:
-	mutex_unlock(&entry->access);
-	if (err < 0)
-		return err;
 	*offset = next;
 	return count;
 }
@@ -369,10 +350,10 @@ static int snd_info_text_entry_open(struct inode *inode, struct file *file)
 	struct snd_info_private_data *data;
 	int err;
 
-	mutex_lock(&info_mutex);
+	guard(mutex)(&info_mutex);
 	err = alloc_info_private(entry, &data);
 	if (err < 0)
-		goto unlock;
+		return err;
 
 	data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
 	if (!data->rbuffer) {
@@ -386,15 +367,12 @@ static int snd_info_text_entry_open(struct inode *inode, struct file *file)
 		err = single_open(file, snd_info_seq_show, data);
 	if (err < 0)
 		goto error;
-	mutex_unlock(&info_mutex);
 	return 0;
 
  error:
 	kfree(data->rbuffer);
 	kfree(data);
 	module_put(entry->module);
- unlock:
-	mutex_unlock(&info_mutex);
 	return err;
 }
 
@@ -549,7 +527,7 @@ int snd_info_card_register(struct snd_card *card)
  */
 void snd_info_card_id_change(struct snd_card *card)
 {
-	mutex_lock(&info_mutex);
+	guard(mutex)(&info_mutex);
 	if (card->proc_root_link) {
 		proc_remove(card->proc_root_link);
 		card->proc_root_link = NULL;
@@ -558,7 +536,6 @@ void snd_info_card_id_change(struct snd_card *card)
 		card->proc_root_link = proc_symlink(card->id,
 						    snd_proc_root->p,
 						    card->proc_root->name);
-	mutex_unlock(&info_mutex);
 }
 
 /*
@@ -574,12 +551,11 @@ void snd_info_card_disconnect(struct snd_card *card)
 	if (card->proc_root)
 		proc_remove(card->proc_root->p);
 
-	mutex_lock(&info_mutex);
+	guard(mutex)(&info_mutex);
 	if (card->proc_root)
 		snd_info_clear_entries(card->proc_root);
 	card->proc_root_link = NULL;
 	card->proc_root = NULL;
-	mutex_unlock(&info_mutex);
 }
 
 /*
@@ -703,9 +679,8 @@ snd_info_create_entry(const char *name, struct snd_info_entry *parent,
 	entry->parent = parent;
 	entry->module = module;
 	if (parent) {
-		mutex_lock(&parent->access);
+		guard(mutex)(&parent->access);
 		list_add_tail(&entry->list, &parent->children);
-		mutex_unlock(&parent->access);
 	}
 	return entry;
 }
@@ -775,9 +750,8 @@ void snd_info_free_entry(struct snd_info_entry * entry)
 		return;
 	if (entry->p) {
 		proc_remove(entry->p);
-		mutex_lock(&info_mutex);
+		guard(mutex)(&info_mutex);
 		snd_info_clear_entries(entry);
-		mutex_unlock(&info_mutex);
 	}
 
 	/* free all children at first */
@@ -786,9 +760,8 @@ void snd_info_free_entry(struct snd_info_entry * entry)
 
 	p = entry->parent;
 	if (p) {
-		mutex_lock(&p->access);
+		guard(mutex)(&p->access);
 		list_del(&entry->list);
-		mutex_unlock(&p->access);
 	}
 	kfree(entry->name);
 	if (entry->private_free)
@@ -804,15 +777,13 @@ static int __snd_info_register(struct snd_info_entry *entry)
 	if (snd_BUG_ON(!entry))
 		return -ENXIO;
 	root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
-	mutex_lock(&info_mutex);
+	guard(mutex)(&info_mutex);
 	if (entry->p || !root)
-		goto unlock;
+		return 0;
 	if (S_ISDIR(entry->mode)) {
 		p = proc_mkdir_mode(entry->name, entry->mode, root);
-		if (!p) {
-			mutex_unlock(&info_mutex);
+		if (!p)
 			return -ENOMEM;
-		}
 	} else {
 		const struct proc_ops *ops;
 		if (entry->content == SNDRV_INFO_CONTENT_DATA)
@@ -821,15 +792,11 @@ static int __snd_info_register(struct snd_info_entry *entry)
 			ops = &snd_info_text_entry_ops;
 		p = proc_create_data(entry->name, entry->mode, root,
 				     ops, entry);
-		if (!p) {
-			mutex_unlock(&info_mutex);
+		if (!p)
 			return -ENOMEM;
-		}
 		proc_set_size(p, entry->size);
 	}
 	entry->p = p;
- unlock:
-	mutex_unlock(&info_mutex);
 	return 0;
 }
 

sound/core/info_oss.c

@@ -29,20 +29,17 @@ int snd_oss_info_register(int dev, int num, char *string)
 		return -ENXIO;
 	if (snd_BUG_ON(num < 0 || num >= SNDRV_CARDS))
 		return -ENXIO;
-	mutex_lock(&strings);
+	guard(mutex)(&strings);
 	if (string == NULL) {
 		x = snd_sndstat_strings[num][dev];
 		kfree(x);
 		x = NULL;
 	} else {
 		x = kstrdup(string, GFP_KERNEL);
-		if (x == NULL) {
-			mutex_unlock(&strings);
+		if (x == NULL)
 			return -ENOMEM;
 	}
-	}
 	snd_sndstat_strings[num][dev] = x;
-	mutex_unlock(&strings);
 	return 0;
 }
 EXPORT_SYMBOL(snd_oss_info_register);
@@ -53,7 +50,7 @@ static int snd_sndstat_show_strings(struct snd_info_buffer *buf, char *id, int d
 	char *str;
 
 	snd_iprintf(buf, "\n%s:", id);
-	mutex_lock(&strings);
+	guard(mutex)(&strings);
 	for (idx = 0; idx < SNDRV_CARDS; idx++) {
 		str = snd_sndstat_strings[idx][dev];
 		if (str) {
@@ -64,7 +61,6 @@ static int snd_sndstat_show_strings(struct snd_info_buffer *buf, char *id, int d
 			snd_iprintf(buf, "%i: %s\n", idx, str);
 		}
 	}
-	mutex_unlock(&strings);
 	if (ok < 0)
 		snd_iprintf(buf, " NOT ENABLED IN CONFIG\n");
 	return ok;