linux-kernel - [PATCH v2 1/3] regmap: debugfs: use snprintf return value in regmap_reg_ranges_read

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Date:	Wed, 30 Sep 2015 20:30:25 +0200
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Mark Brown <broonie@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] regmap: debugfs: use snprintf return value in regmap_reg_ranges_read_file()

Calling strlen() no less than three times on entry is silly. Since
we're formatting into a buffer with plenty of room, there's no chance
of truncation, so snprintf() has actually returned the value we want,
meaning we don't even have to call strlen once.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 drivers/base/regmap/regmap-debugfs.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index f42f2bac6466..d26b9c3ab812 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -339,6 +339,7 @@ static ssize_t regmap_reg_ranges_read_file(struct file *file,
 	char *buf;
 	char *entry;
 	int ret;
+	unsigned entry_len;
 
 	if (*ppos < 0 || !count)
 		return -EINVAL;
@@ -366,18 +367,18 @@ static ssize_t regmap_reg_ranges_read_file(struct file *file,
 	p = 0;
 	mutex_lock(&map->cache_lock);
 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
-		snprintf(entry, PAGE_SIZE, "%x-%x",
-			 c->base_reg, c->max_reg);
+		entry_len = snprintf(entry, PAGE_SIZE, "%x-%x",
+				     c->base_reg, c->max_reg);
 		if (p >= *ppos) {
-			if (buf_pos + 1 + strlen(entry) > count)
+			if (buf_pos + 1 + entry_len > count)
 				break;
 			snprintf(buf + buf_pos, count - buf_pos,
 				 "%s", entry);
-			buf_pos += strlen(entry);
+			buf_pos += entry_len;
 			buf[buf_pos] = '\n';
 			buf_pos++;
 		}
-		p += strlen(entry) + 1;
+		p += entry_len + 1;
 	}
 	mutex_unlock(&map->cache_lock);
 
-- 
2.1.3

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