Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 21 Jan 2019 13:20:33 +1300 | Subject | Re: fix int_sqrt() for very large numbers |
| |
On Sun, Jan 20, 2019 at 4:15 AM Florian La Roche <florian.laroche@googlemail.com> wrote: > > @@ -52,7 +52,7 @@ u32 int_sqrt64(u64 x) > if (x <= ULONG_MAX) > return int_sqrt((unsigned long) x); > > - m = 1ULL << (fls64(x) & ~1ULL); > + m = 1ULL << ((fls64(x) - 1) & ~1ULL);
I've applied this part of the patch as commit fbfaf851902c ("fix int_sqrt64() for very large numbers") with slightly edited commit log.
I still think there are some oddities in here in the types. I mentioned the caller that unnecessarily does the int_sqrt64() twice, even though the outer one doesn't actually take a 64-bit value.
But in the very line above, there's another type oddity: the "& ~1ULL" is entirely the wrong type. The shift *count* shouldn't be an unsigned long long, so that type doesn't make much sense. It should be just a ~1, or even just "62".
But I didn't actually start micro-editing the patch, and just did that one-liner off-by-one fix.
Linus
| |