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bcachefs: mean_and_variance: Avoid too-large shift amounts

Shifting a value by the width of its type or more is undefined.

Signed-off-by: Tavian Barnes <tavianator@tavianator.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Tavian Barnes 2024-06-21 16:38:44 -04:00 committed by Kent Overstreet
parent a97b43fac5
commit 73f88592dd

View File

@ -111,11 +111,11 @@ static inline u128_u u128_shl(u128_u i, s8 shift)
{
u128_u r;
r.lo = i.lo << shift;
r.lo = i.lo << (shift & 63);
if (shift < 64)
r.hi = (i.hi << shift) | (i.lo >> (64 - shift));
r.hi = (i.hi << (shift & 63)) | (i.lo >> (-shift & 63));
else {
r.hi = i.lo << (shift - 64);
r.hi = i.lo << (-shift & 63);
r.lo = 0;
}
return r;