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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 6a596632889b0a341771591310d5f26970412cf0..a7197e41eff0caa15cb57bf9ec7ceef093dc24e4 100644 (file)
--- 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 int regmap_open_file(struct inode *inode, struct file *file)