Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31;
Date:   Tue, 24 Oct 2023 13:55:44 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Stephen Boyd <sboyd@kernel.org>
Cc:     David Laight <David.Laight@aculab.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Sebastian Reichel <sebastian.reichel@collabora.com>,
        linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@collabora.com
Subject: Re: [PATCH v3 1/1] clk: divider: Fix divisor masking on 64 bit
 platforms
Message-ID: <ZTeisLk5zvF2Fh/B@smile.fi.intel.com>
References: <20230630183835.464216-1-sebastian.reichel@collabora.com>
 <a9756c11ea3f111d45e85e0f3928bdd8.sboyd@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <a9756c11ea3f111d45e85e0f3928bdd8.sboyd@kernel.org>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Precedence: bulk

On Mon, Oct 23, 2023 at 08:34:12PM -0700, Stephen Boyd wrote:
> Quoting Sebastian Reichel (2023-06-30 11:38:35)

> > --- a/include/linux/math.h
> > +++ b/include/linux/math.h
> > @@ -36,6 +36,17 @@
> >  
> >  #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
> >  
> > +/**
> > + * DIV_ROUND_UP_NO_OVERFLOW - divide two numbers and always round up
> > + * @n: numerator / dividend
> > + * @d: denominator / divisor
> > + *
> > + * This functions does the same as DIV_ROUND_UP, but internally uses a
> > + * division and a modulo operation instead of math tricks. This way it
> > + * avoids overflowing when handling big numbers.
> > + */
> > +#define DIV_ROUND_UP_NO_OVERFLOW(n, d) (((n) / (d)) + !!((n) % (d)))
> 
> Can you get someone to review/ack this macro? Maybe Andy?
> 
> > +
> >  #define DIV_ROUND_DOWN_ULL(ll, d) \
> >         ({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })

First of all, it should be a separate patch and second, same issue is being
discussed here (as it needs to be fixed in UAPI header directly):

https://lore.kernel.org/all/your-ad-here.call-01697881440-ext-2458@work.hours/

-- 
With Best Regards,
Andy Shevchenko