Re: [PATCH] clocksource_cyc2ns: avoid overflowing 64 bits
From: John Stultz
Date: Wed Nov 16 2016 - 15:01:05 EST
On Wed, Nov 16, 2016 at 11:56 AM, Chris Metcalf <cmetcalf@xxxxxxxxxxxx> wrote:
> On 11/16/2016 2:45 PM, John Stultz wrote:
>> On Wed, Nov 16, 2016 at 11:30 AM, Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
>>> diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
>>> index 08398182f56e..5444429884b8 100644
>>> --- a/include/linux/clocksource.h
>>> +++ b/include/linux/clocksource.h
>>> @@ -171,6 +171,10 @@ static inline u32 clocksource_hz2mult(u32 hz, u32
>>> * Converts cycles to nanoseconds, using the given mult and shift.
>>> + * The code is optimized for performance and not intended to work
>>> + * with absolute clocksource cycles, as it will easily overflow,
>>> + * but just intended for relative (delta) clocksource cycles.
>>> + *
>>> * XXX - This could use some mult_lxl_ll() asm optimization
>> Just as a heads up, it seems your working against an older kernel, as
>> this didn't apply. Its simple enough to fix up, so I'll do so, but in
>> the future, please submit patches against something close to Linus
> Oops, sorry; it wasn't version skew (I'm at v4.9-rc4) but whitespace damage.
> I assumed if I just pasted the patch into Thunderbird it would work, since
> it had
> no tabs. But bizarrely, if I look at the patch in the mailer, it shows a
> prefix, but when I save the email to a file, it has a three-space prefix.
Yea. Not many mailers can be trusted with sending patches. I'd
recommend git-send-email. :)