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Re: [RFC v4 14/22] clockevents: clockevents_program_event(): turn clc into unsigned long

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  Re: [RFC v4 14/22] clockevents: clockevents_program_event(): turn  clc into unsigned long Thomas Gleixner <tglx@linutronix.de> - 2016-08-25 15:30 +0200
    Re: [RFC v4 14/22] clockevents: clockevents_program_event(): turn clc into unsigned long Nicolai Stange <nicstange@gmail.com> - 2016-08-27 17:30 +0200

#1470144 — Re: [RFC v4 14/22] clockevents: clockevents_program_event(): turn clc into unsigned long

On Tue, 23 Aug 2016, Nicolai Stange wrote:

> Right now, being of type unsigned long long, the clc local variable in
> clockevents_program_event() is unnecessarily wide as it gets cast to
> unsigned long anyway.

Congrats! You just broke 32bit systems. When delta is sufficiently large then
the mult overflows....
 
Thanks,

	tglx

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#1471204 — Re: [RFC v4 14/22] clockevents: clockevents_program_event(): turn clc into unsigned long

Thomas Gleixner <tglx@linutronix.de> writes:

> On Tue, 23 Aug 2016, Nicolai Stange wrote:
>
>> Right now, being of type unsigned long long, the clc local variable in
>> clockevents_program_event() is unnecessarily wide as it gets cast to
>> unsigned long anyway.
>
> Congrats! You just broke 32bit systems. When delta is sufficiently large then
> the mult overflows....

The 32bit breakage has been introduced in [13/22] ("clockevents: check a
programmed delta's bounds in terms of cycles") already -- please see my
reply there.

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