From: john stultz <johnstul@us.ibm.com>
To: Nicolas Pitre <nico@fluxnic.net>, Thomas Gleixner <tglx@linutronix.de>
Cc: lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] clocks_calc_mult_shift(): rename minsec argument according to actual usage
Date: Tue, 11 Jan 2011 09:24:04 -0800 [thread overview]
Message-ID: <1294766644.3441.9.camel@work-vm> (raw)
In-Reply-To: <alpine.LFD.2.00.1101111207140.17086@xanadu.home>
On Tue, 2011-01-11 at 12:18 -0500, Nicolas Pitre wrote:
> The minsec argument to clocks_calc_mult_shift() is misnamed. It is used
> to clamp the magnitude of the mult factor so that a multiplication with
> any value in the given range won't overflow a 64 bit result. Let's
> rename it to match the actual usage.
>
> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
Thomas, mind picking this up for 2.6.38?
thanks
-john
> diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
> index c18d7ef..8588abc 100644
> --- a/kernel/time/clocksource.c
> +++ b/kernel/time/clocksource.c
> @@ -113,7 +113,7 @@ EXPORT_SYMBOL_GPL(timecounter_cyc2time);
> * @shift: pointer to shift variable
> * @from: frequency to convert from
> * @to: frequency to convert to
> - * @minsec: guaranteed runtime conversion range in seconds
> + * @maxsec: guaranteed runtime conversion range in seconds
> *
> * The function evaluates the shift/mult pair for the scaled math
> * operations of clocksources and clockevents.
> @@ -122,7 +122,7 @@ EXPORT_SYMBOL_GPL(timecounter_cyc2time);
> * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
> * event @to is the counter frequency and @from is NSEC_PER_SEC.
> *
> - * The @minsec conversion range argument controls the time frame in
> + * The @maxsec conversion range argument controls the time frame in
> * seconds which must be covered by the runtime conversion with the
> * calculated mult and shift factors. This guarantees that no 64bit
> * overflow happens when the input value of the conversion is
> @@ -131,7 +131,7 @@ EXPORT_SYMBOL_GPL(timecounter_cyc2time);
> * factors.
> */
> void
> -clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
> +clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec)
> {
> u64 tmp;
> u32 sft, sftacc= 32;
> @@ -140,7 +140,7 @@ clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
> * Calculate the shift factor which is limiting the conversion
> * range:
> */
> - tmp = ((u64)minsec * from) >> 32;
> + tmp = ((u64)maxsec * from) >> 32;
> while (tmp) {
> tmp >>=1;
> sftacc--;
next prev parent reply other threads:[~2011-01-11 17:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-11 17:18 [PATCH] clocks_calc_mult_shift(): rename minsec argument according to actual usage Nicolas Pitre
2011-01-11 17:24 ` john stultz [this message]
2011-01-12 11:30 ` [tip:timers/urgent] time: Rename misnamed minsec argument of clocks_calc_mult_shift() tip-bot for Nicolas Pitre
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