From 42bffe1abdfe0543b54c0d29550e9a2bcd9edd34 Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie@kernel.org>
Date: Sat, 19 Sep 2015 07:12:34 -0700
Subject: [PATCH] regmap: debugfs: Don't bother actually printing when
 calculating max length

commit 176fc2d5770a0990eebff903ba680d2edd32e718 upstream.

The in kernel snprintf() will conveniently return the actual length of
the printed string even if not given an output beffer at all so just do
that rather than relying on the user to pass in a suitable buffer,
ensuring that we don't need to worry if the buffer was truncated due to
the size of the buffer passed in.

Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 drivers/base/regmap/regmap-debugfs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index d805eb58343f..023a9d79e26a 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -23,8 +23,7 @@ static struct dentry *regmap_debugfs_root;
 /* Calculate the length of a fixed format  */
 static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
 {
-	snprintf(buf, buf_size, "%x", max_val);
-	return strlen(buf);
+	return snprintf(NULL, 0, "%x", max_val);
 }
 
 static ssize_t regmap_name_read_file(struct file *file,