[PATCH v2 7/7] regmap: debugfs: Use guard to simplify code

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

Replace open-coded mutex_lock()/unlock() pairs with guard() and
scoped_guard() across the debugfs code.

 - regmap_debugfs_get_dump_start(): guard(mutex) replaces three
   unlock sites (kzalloc failure, cache hit, end-of-function).

 - regmap_next_readable_reg(): early return for the common case
   and scoped_guard for the cache fallback path.

 - regmap_reg_ranges_read_file(): scoped_guard wraps the cache
   iteration loop.

 - regmap_debugfs_init(): scoped_guard for single list_add.

 - regmap_debugfs_exit(): flatten if/else into early return and
   scoped_guard for the early-list cleanup.

 - regmap_debugfs_initcall(): guard(mutex) held to function end.

No functional change.

Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 drivers/base/regmap/regmap-debugfs.c | 63 +++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 34 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 0a9c27426f15..b2ae52a21331 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -107,7 +107,7 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 	 * If we don't have a cache build one so we don't have to do a
 	 * linear scan each time.
 	 */
-	mutex_lock(&map->cache_lock);
+	guard(mutex)(&map->cache_lock);
 	i = base;
 	if (list_empty(&map->debugfs_off_cache)) {
 		for (; i <= map->max_register; i += map->reg_stride) {
@@ -129,7 +129,6 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 				c = kzalloc_obj(*c);
 				if (!c) {
 					regmap_debugfs_free_dump_cache(map);
-					mutex_unlock(&map->cache_lock);
 					return base;
 				}
 				c->min = p;
@@ -162,14 +161,12 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 			fpos_offset = from - c->min;
 			reg_offset = fpos_offset / map->debugfs_tot_len;
 			*pos = c->min + (reg_offset * map->debugfs_tot_len);
-			mutex_unlock(&map->cache_lock);
 			return c->base_reg + (reg_offset * map->reg_stride);
 		}
 
 		*pos = c->max;
 		ret = c->max_reg;
 	}
-	mutex_unlock(&map->cache_lock);
 
 	return ret;
 }
@@ -191,10 +188,10 @@ static int regmap_next_readable_reg(struct regmap *map, int reg)
 	struct regmap_debugfs_off_cache *c;
 	int ret = -EINVAL;
 
-	if (regmap_printable(map, reg + map->reg_stride)) {
-		ret = reg + map->reg_stride;
-	} else {
-		mutex_lock(&map->cache_lock);
+	if (regmap_printable(map, reg + map->reg_stride))
+		return reg + map->reg_stride;
+
+	scoped_guard(mutex, &map->cache_lock) {
 		list_for_each_entry(c, &map->debugfs_off_cache, list) {
 			if (reg > c->max_reg)
 				continue;
@@ -203,8 +200,8 @@ static int regmap_next_readable_reg(struct regmap *map, int reg)
 				break;
 			}
 		}
-		mutex_unlock(&map->cache_lock);
 	}
+
 	return ret;
 }
 
@@ -393,19 +390,19 @@ static ssize_t regmap_reg_ranges_read_file(struct file *file,
 	/* Reset file pointer as the fixed-format of the `registers'
 	 * file is not compatible with the `range' file */
 	p = 0;
-	mutex_lock(&map->cache_lock);
-	list_for_each_entry(c, &map->debugfs_off_cache, list) {
-		entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
-				     c->base_reg, c->max_reg);
-		if (p >= *ppos) {
-			if (buf_pos + entry_len > count)
-				break;
-			memcpy(buf + buf_pos, entry, entry_len);
-			buf_pos += entry_len;
+	scoped_guard(mutex, &map->cache_lock) {
+		list_for_each_entry(c, &map->debugfs_off_cache, list) {
+			entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
+					     c->base_reg, c->max_reg);
+			if (p >= *ppos) {
+				if (buf_pos + entry_len > count)
+					break;
+				memcpy(buf + buf_pos, entry, entry_len);
+				buf_pos += entry_len;
+			}
+			p += entry_len;
 		}
-		p += entry_len;
 	}
-	mutex_unlock(&map->cache_lock);
 
 	kfree(entry);
 	ret = buf_pos;
@@ -552,9 +549,8 @@ void regmap_debugfs_init(struct regmap *map)
 		if (!node)
 			return;
 		node->map = map;
-		mutex_lock(&regmap_debugfs_early_lock);
-		list_add(&node->link, &regmap_debugfs_early_list);
-		mutex_unlock(&regmap_debugfs_early_lock);
+		scoped_guard(mutex, &regmap_debugfs_early_lock)
+			list_add(&node->link, &regmap_debugfs_early_list);
 		return;
 	}
 
@@ -653,29 +649,29 @@ void regmap_debugfs_init(struct regmap *map)
 
 void regmap_debugfs_exit(struct regmap *map)
 {
+	struct regmap_debugfs_node *node, *tmp;
+
 	if (map->debugfs) {
 		debugfs_remove_recursive(map->debugfs);
-		mutex_lock(&map->cache_lock);
-		regmap_debugfs_free_dump_cache(map);
-		mutex_unlock(&map->cache_lock);
+		scoped_guard(mutex, &map->cache_lock)
+			regmap_debugfs_free_dump_cache(map);
 		if (map->debugfs_dummy_id >= 0) {
 			ida_free(&dummy_ida, map->debugfs_dummy_id);
 			map->debugfs_dummy_id = -1;
 		}
 		kfree(map->debugfs_name);
 		map->debugfs_name = NULL;
-	} else {
-		struct regmap_debugfs_node *node, *tmp;
 
-		mutex_lock(&regmap_debugfs_early_lock);
-		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
-					 link) {
+		return;
+	}
+
+	scoped_guard(mutex, &regmap_debugfs_early_lock) {
+		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
 			if (node->map == map) {
 				list_del(&node->link);
 				kfree(node);
 			}
 		}
-		mutex_unlock(&regmap_debugfs_early_lock);
 	}
 }
 
@@ -685,11 +681,10 @@ void regmap_debugfs_initcall(void)
 
 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
 
-	mutex_lock(&regmap_debugfs_early_lock);
+	guard(mutex)(&regmap_debugfs_early_lock);
 	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
 		regmap_debugfs_init(node->map);
 		list_del(&node->link);
 		kfree(node);
 	}
-	mutex_unlock(&regmap_debugfs_early_lock);
 }

-- 
2.51.0