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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: "Ardelean, Alexandru" <alexandru.Ardelean@analog.com>,
	"lars@metafoo.de" <lars@metafoo.de>,
	"kernel-janitors@vger.kernel.org"
	<kernel-janitors@vger.kernel.org>,
	"Popa, Stefan Serban" <StefanSerban.Popa@analog.com>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Hennerich, Michael" <Michael.Hennerich@analog.com>,
	"pmeerw@pmeerw.net" <pmeerw@pmeerw.net>,
	"knaack.h@gmx.de" <knaack.h@gmx.de>
Subject: Re: [PATCH] iio: imu: adis16480: clean up a condition
Date: Sun, 6 Oct 2019 21:14:40 +0300	[thread overview]
Message-ID: <20191006181439.GU22609@kadam> (raw)
In-Reply-To: <20191006095133.24fb89be@archlinux>

On Sun, Oct 06, 2019 at 09:51:33AM +0100, Jonathan Cameron wrote:
> On Thu, 26 Sep 2019 14:36:30 +0300
> Dan Carpenter <dan.carpenter@oracle.com> wrote:
> 
> > On Thu, Sep 26, 2019 at 11:06:39AM +0000, Ardelean, Alexandru wrote:
> > > On Thu, 2019-09-26 at 11:10 +0300, Dan Carpenter wrote:  
> > > > [External]
> > > > 
> > > > The "t" variable is unsigned so it can't be less than zero.  We really
> > > > are just trying to prevent divide by zero bugs so just checking against
> > > > zero is sufficient.
> 
> I'm not sure that true.  It if were signed we'd be detecting that the
> input from userspace was negative.

It does a really bad job of that though so it raises more questions than
answers.  Maybe just one of the parameters is negative or maybe the
multiply or the addition overflowed?  Should scenarios those be checked?

It turns out none of those situations matter, only divide by zero needs
to be checked.

regards,
dan carpenter





WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: "Ardelean, Alexandru" <alexandru.Ardelean@analog.com>,
	"lars@metafoo.de" <lars@metafoo.de>,
	"kernel-janitors@vger.kernel.org"
	<kernel-janitors@vger.kernel.org>,
	"Popa, Stefan Serban" <StefanSerban.Popa@analog.com>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Hennerich, Michael" <Michael.Hennerich@analog.com>,
	"pmeerw@pmeerw.net" <pmeerw@pmeerw.net>,
	"knaack.h@gmx.de" <knaack.h@gmx.de>
Subject: Re: [PATCH] iio: imu: adis16480: clean up a condition
Date: Sun, 06 Oct 2019 18:14:40 +0000	[thread overview]
Message-ID: <20191006181439.GU22609@kadam> (raw)
In-Reply-To: <20191006095133.24fb89be@archlinux>

On Sun, Oct 06, 2019 at 09:51:33AM +0100, Jonathan Cameron wrote:
> On Thu, 26 Sep 2019 14:36:30 +0300
> Dan Carpenter <dan.carpenter@oracle.com> wrote:
> 
> > On Thu, Sep 26, 2019 at 11:06:39AM +0000, Ardelean, Alexandru wrote:
> > > On Thu, 2019-09-26 at 11:10 +0300, Dan Carpenter wrote:  
> > > > [External]
> > > > 
> > > > The "t" variable is unsigned so it can't be less than zero.  We really
> > > > are just trying to prevent divide by zero bugs so just checking against
> > > > zero is sufficient.
> 
> I'm not sure that true.  It if were signed we'd be detecting that the
> input from userspace was negative.

It does a really bad job of that though so it raises more questions than
answers.  Maybe just one of the parameters is negative or maybe the
multiply or the addition overflowed?  Should scenarios those be checked?

It turns out none of those situations matter, only divide by zero needs
to be checked.

regards,
dan carpenter

  reply	other threads:[~2019-10-06 18:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26  8:10 [PATCH] iio: imu: adis16480: clean up a condition Dan Carpenter
2019-09-26  8:10 ` Dan Carpenter
2019-09-26 11:06 ` Ardelean, Alexandru
2019-09-26 11:06   ` Ardelean, Alexandru
2019-09-26 11:36   ` Dan Carpenter
2019-09-26 11:36     ` Dan Carpenter
2019-10-06  8:51     ` Jonathan Cameron
2019-10-06  8:51       ` Jonathan Cameron
2019-10-06 18:14       ` Dan Carpenter [this message]
2019-10-06 18:14         ` Dan Carpenter
2019-10-07  9:21         ` Jonathan Cameron
2019-10-07  9:21           ` Jonathan Cameron
2019-10-07 14:18           ` Dan Carpenter
2019-10-07 14:18             ` Dan Carpenter

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