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From: Harman Kalra <hkalra@marvell.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: <stephen@networkplumber.org>, <pbhagavatula@marvell.com>,
	<stable@dpdk.org>, <dev@dpdk.org>, <david.marchand@redhat.com>
Subject: Re: [dpdk-stable] [EXT] Re: [PATCH] eal: fix macros to align value
Date: Wed, 24 Jun 2020 15:32:49 +0530
Message-ID: <20200624100248.GB73382@outlook.office365.com> (raw)
In-Reply-To: <2473627.Zvk6BpfnDP@thomas>

On Wed, Jun 24, 2020 at 10:30:18AM +0200, Thomas Monjalon wrote:
> 24/06/2020 10:24, Harman Kalra:
> > On Wed, Jun 24, 2020 at 10:13:18AM +0200, Thomas Monjalon wrote:
> > > 09/06/2020 21:17, Harman Kalra:
> > > > Found an issue while using RTE_ALIGN_MUL_NEAR with an
> > > > expression, like as passed in estimate_tsc_freq().
> > > > RTE_ALIGN_MUL_FLOOR resulted in unexpected value in the
> > > > above function as division has more precedence over
> > > > substraction.
> > > 
> > > The only change I see is adding parenthesis around v.
> > > Am I right?
> > 
> > Yes, parathesis are required if an expression is passed.
> 
> I think the commit log needs to be updated.
> I don't see the relation between
> 	"division has more precedence over substraction"
> and
> 	"parathesis are required if an expression is passed"

By "division has more precedence over substraction", I tried to
highlight the issue which resulted in unexpected value, but yes
it is sounding confusing. I will reword the commit message and send
V2.

> 
> 
> > > >  #define RTE_ALIGN_MUL_CEIL(v, mul) \
> > > > -	(((v + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > > +	((((v) + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > [...]
> > > >  #define RTE_ALIGN_MUL_FLOOR(v, mul) \
> > > > -	((v / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > > +	(((v) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > [...]
> > > >  	({							\
> > > >  		typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul);	\
> > > >  		typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul);	\
> > > > -		(ceil - v) > (v - floor) ? floor : ceil;	\
> > > > +		(ceil - (v)) > ((v) - floor) ? floor : ceil;	\
> > > >  	})
> > > 
> > > 
> > > 
> > > 
> > 
> 
> 
> 
> 
> 

  reply	other threads:[~2020-06-24 10:03 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-09 19:17 [dpdk-stable] " Harman Kalra
2020-06-24  8:13 ` Thomas Monjalon
2020-06-24  8:24   ` [dpdk-stable] [EXT] " Harman Kalra
2020-06-24  8:30     ` Thomas Monjalon
2020-06-24 10:02       ` Harman Kalra [this message]
2020-06-24 10:20       ` [dpdk-stable] [PATCH v2] " Harman Kalra
2020-07-11  9:44         ` Thomas Monjalon

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