[PATCH v1 5/5] hash.h: Silence a clang -Wshorten-64-to-32 warning

From: Ian Rogers
Date: Thu Apr 03 2025 - 12:58:07 EST


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@xxxxxxxxxx>
---
include/linux/hash.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/hash.h b/include/linux/hash.h
index 38edaa08f862..ecc8296cb397 100644
--- a/include/linux/hash.h
+++ b/include/linux/hash.h
@@ -75,7 +75,7 @@ static __always_inline u32 hash_64_generic(u64 val, unsigned int bits)
{
#if BITS_PER_LONG == 64
/* 64x64-bit multiply is efficient on all 64-bit processors */
- return val * GOLDEN_RATIO_64 >> (64 - bits);
+ return (u32)(val * GOLDEN_RATIO_64 >> (64 - bits));
#else
/* Hash 64 bits using only 32x32-bit multiply. */
return hash_32((u32)val ^ __hash_32(val >> 32), bits);
--
2.49.0.504.g3bcea36a83-goog