linux-kernel - [PATCH] vsprintf: Use non-atomic bitmap API when applicable

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Message-Id: <1abf81a5e509d372393bd22041eed4ebc07ef9f7.1638023178.git.christophe.jaillet@wanadoo.fr>
Date:   Sat, 27 Nov 2021 15:27:35 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     pmladek@...e.com, rostedt@...dmis.org, senozhatsky@...omium.org,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] vsprintf: Use non-atomic bitmap API when applicable

The 'set' bitmap is local to this function. No concurrent access to it is
possible.
So prefer the non-atomic '__[set|clear]_bit()' function to save a few
cycles.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 lib/vsprintf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 9a2bc00b5952..c130dcaca5e2 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -3566,7 +3566,7 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
 				++fmt;
 
 			for ( ; *fmt && *fmt != ']'; ++fmt, ++len)
-				set_bit((u8)*fmt, set);
+				__set_bit((u8)*fmt, set);
 
 			/* no ']' or no character set found */
 			if (!*fmt || !len)
@@ -3576,7 +3576,7 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
 			if (negate) {
 				bitmap_complement(set, set, 256);
 				/* exclude null '\0' byte */
-				clear_bit(0, set);
+				__clear_bit(0, set);
 			}
 
 			/* match must be non-empty */
-- 
2.30.2