Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH] staging: pi433: Use div64_u64 instead of do_div | Date | Wed, 19 Oct 2022 10:31:17 +0000 |
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From: Kang Minchul > Sent: 19 October 2022 10:40 > > This commit removes warning generated by cocci as follows: > > do_div() does a 64-by-32 division, please consider using div64_u64 instead. > > Using div64_u64 instead of do_div can avoid potential truncation.
Cocci is lying to you.
do_div() exists because a 64 by 32 bit divide is significantly faster than a 64 by 64 divide. This is particularly true on 32bit cpu, but is also true on Intel x86_64 bit cpu.
So unless the result might actually be larger than 32 bits (which requires code analysis) then do_div() is correct.
David
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