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From: Chin-Chun Chen <chinchunchen2001@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Chin-Chun Chen <chinchunchen2001@gmail.com>
Subject: [PATCH] include/linux/bitops.h: Fix function fns
Date: Sat, 13 Apr 2024 13:28:50 +0800
Message-Id: <20240413052850.9419-1-chinchunchen2001@gmail.com>
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Modified the function fns to resolve a calculation error by:
1. Reducing n first.
2. Adding 1 at the end to get the correct index.

This commit improves the accuracy and reliability of the code.

Signed-off-by: Chin-Chun Chen <chinchunchen2001@gmail.com>
---
 include/linux/bitops.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 2ba557e067fe..2457610f74eb 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -258,8 +258,8 @@ static inline unsigned long fns(unsigned long word, unsigned int n)
 
 	while (word) {
 		bit = __ffs(word);
-		if (n-- == 0)
-			return bit;
+		if (--n == 0)
+			return bit + 1;
 		__clear_bit(bit, &word);
 	}
 

base-commit: 8f2c057754b25075aa3da132cd4fd4478cdab854
-- 
2.40.1