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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	James Bottomley <JBottomley@Odin.com>,
	Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] lib/string_helpers.c: don't lose precision in string_get_size()
Date: Tue, 27 Oct 2015 11:34:33 +0200	[thread overview]
Message-ID: <1445938473.6332.17.camel@linux.intel.com> (raw)
In-Reply-To: <87fv0wyah4.fsf@vitty.brq.redhat.com>

On Tue, 2015-10-27 at 09:36 +0100, Vitaly Kuznetsov wrote:
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> 
> > On Mon, 2015-10-26 at 14:55 +0100, Vitaly Kuznetsov wrote:
> > > string_get_size() loses precision when there is a remainder for
> > > blk_size / divisor[units] and size is big enough. E.g
> > > string_get_size(8192, 4096, STRING_UNITS_10, ...) returns "32.7
> > > MB"
> > > while it is supposed to return "33.5 MB". For some artificial
> > > inputs
> > > the result can be ridiculously wrong, e.g.
> > > string_get_size(3000, 1900, STRING_UNITS_10, ...) returns "3.00
> > > MB"
> > > when "5.70 MB" is expected.

[]

> > > -	int i, j;
> > > -	u32 remainder = 0, sf_cap, exp;
> > > +	int order = 0, j;
> > > +	u64 remainder = 0;
> > > +	u32 sf_cap;
> > >  	char tmp[8];
> > >  	const char *unit;
> > >  
> > >  	tmp[0] = '\0';
> > > -	i = 0;
> > 
> > Maybe leave i naming as is. Your order is not strictly speaking an
> > order, rather 3x order. I will make patch neater.
> > 
> 
> While reading the original function I found meaningless 'i' and 'j'
> here
> a bit consufing but yes, strictly speaking 'i' is a power of
> divisor[units], not 'order' and I don't have a good name for it
> (div_power?). I'll revert back to 'i' in v2.

I agree that names suck, however it might be better to have separate
patch to fix naming.

Rasmus?

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy


  reply	other threads:[~2015-10-27  9:36 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-26 13:55 [PATCH 0/3] lib/string_helpers: fix precision issues and introduce tests Vitaly Kuznetsov
2015-10-26 13:55 ` [PATCH 1/3] lib/string_helpers: change blk_size to u32 for string_get_size() interface Vitaly Kuznetsov
2015-10-26 13:55 ` [PATCH 2/3] lib/string_helpers.c: don't lose precision in string_get_size() Vitaly Kuznetsov
2015-10-26 16:08   ` Andy Shevchenko
2015-10-27  8:36     ` Vitaly Kuznetsov
2015-10-27  9:34       ` Andy Shevchenko [this message]
2015-10-26 21:48   ` Rasmus Villemoes
2015-10-27  8:45     ` Vitaly Kuznetsov
2015-10-26 13:55 ` [PATCH 3/3] lib/test-string_helpers.c: add string_get_size() tests Vitaly Kuznetsov
2015-10-26 15:13   ` Andy Shevchenko
2015-10-26 15:18     ` Vitaly Kuznetsov
2015-10-26 15:21       ` Andy Shevchenko
2015-10-26 15:50         ` Vitaly Kuznetsov
2015-10-26 21:54   ` Rasmus Villemoes
2015-10-27  8:56     ` Vitaly Kuznetsov

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