linux-kernel - [PATCH v1 3/5] bitops: Silence a clang -Wshorten-64-to-32 warning

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Message-ID: <20250403165702.396388-4-irogers@google.com>
Date: Thu,  3 Apr 2025 09:57:00 -0700
From: Ian Rogers <irogers@...gle.com>
To: Yury Norov <yury.norov@...il.com>, Rasmus Villemoes <linux@...musvillemoes.dk>, 
	Arnd Bergmann <arnd@...db.de>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Ian Rogers <irogers@...gle.com>, 
	Adrian Hunter <adrian.hunter@...el.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Jakub Kicinski <kuba@...nel.org>, Jacob Keller <jacob.e.keller@...el.com>, linux-arch@...r.kernel.org, 
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH v1 3/5] bitops: Silence a clang -Wshorten-64-to-32 warning

The clang warning -Wshorten-64-to-32 can be useful to catch
inadvertent truncation. In some instances this truncation can lead to
changing the sign of a result, for example, truncation to return an
int to fit a sort routine. Silence the warning by making the implicit
truncation explicit.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 include/asm-generic/bitops/fls64.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/asm-generic/bitops/fls64.h b/include/asm-generic/bitops/fls64.h
index 866f2b2304ff..9ad3ff12f454 100644
--- a/include/asm-generic/bitops/fls64.h
+++ b/include/asm-generic/bitops/fls64.h
@@ -21,7 +21,7 @@ static __always_inline int fls64(__u64 x)
 	__u32 h = x >> 32;
 	if (h)
 		return fls(h) + 32;
-	return fls(x);
+	return fls((__u32)x);
 }
 #elif BITS_PER_LONG == 64
 static __always_inline int fls64(__u64 x)
-- 
2.49.0.504.g3bcea36a83-goog