Thread (2 messages) 2 messages, 2 authors, 2015-06-05

Re: [Y2038] [PATCH] fbdev: radeon: Remove 'struct timeval' usage

From: Arnd Bergmann <arnd@arndb.de>
Date: 2015-06-05 21:12:29
Also in: lkml

On Friday 05 June 2015 00:55:05 Tina Ruchandani wrote:
quoted
quoted
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+     hz = 1000000/delta;
This needs to be on of the do_div family.

Dave.
Hi Dave,
I build-tested the patch for both 32-bit and 64-bit x86. If my
understanding is correct, since the divisor is 64-bit here, the
compiler will do "if (delta > 1000000) hz = 0; else hz > 1000000/(s32)delta" automatically?
In general, is this a good thumb-rule to follow - use do_div if the
dividend is 64-bit, and normal divide operator if only the divisor is
64-bit?
I got a build error on 32-bit arm now. There is already a check
for an overflow of 10 seconds in there (10 million microseconds),
so it is safe to do the easiest fix is to cast that microsecond
value to a u32.

	Arnd
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