Messages in this thread | | | Date | Fri, 1 May 2015 14:29:52 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: regression in ktime.h circa 3.16.0-rc5+ breaks lirc irsend, bad commit 166afb64511 |
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On Fri, 1 May 2015, John Stultz wrote:
> So yea. I see the issue now. The ktime_divns() function uses do_div > which is an unsigned divide. So negative numbers look like large > numbers, and it doesn't do sign-extension, so when it divides we lose > the sign bit.
That doesn't stop there. On 32-bit systems, if the divisor is not constant or too large, then __ktime_divns() is used. If you look at the code for __ktime_divns(), you'll notice it would get into an infinite loop if you pass it a negative divisor.
Nicolas
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