Messages in this thread | | | Date | Mon, 14 Sep 2015 20:27:08 -0700 | Subject | Re: [RFC][PATCH 0/5] Fixes for abs() usage on 64bit values | From | John Stultz <> |
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On Mon, Sep 14, 2015 at 6:49 PM, Tejun Heo <tj@kernel.org> wrote: > Hello, > > On Mon, Sep 14, 2015 at 06:05:19PM -0700, John Stultz wrote: >> As noted in include/linux/kernel.h: >> "abs() should not be used for 64-bit types (s64, u64, long long) >> - use abs64() for those." >> >> Unfortunately, there are quite a number of places where abs() >> was used w/ 64bit values in the kernel, and the results are >> then silently capped to 32-bit values on 32-bit systems. > > I don't get it. Why can't we just do the following? > > #define abs(x) \ > ({ \ > typeof(x) __x = (x); \ > __x < 0 ? -__x : __x; \ > }) >
Yea. The above make sense to me, but I suspect there's some very subtle reason for the existing separated logic. But I'd have to defer to akpm for hints on that.
thanks -john
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