From: Dan Carpenter <dan.carpenter@oracle.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Keerthy <j-keerthy@ti.com>, Amit Kucheria <amitk@kernel.org>,
Zhang Rui <rui.zhang@intel.com>,
linux-pm@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] thermal: k3_j72xx_bandgap: Fix array underflow in prep_lookup_table()
Date: Sat, 21 May 2022 10:04:49 +0300 [thread overview]
Message-ID: <20220521070448.GE23160@kadam> (raw)
In-Reply-To: <20220521065615.GD23160@kadam>
On Sat, May 21, 2022 at 09:56:16AM +0300, Dan Carpenter wrote:
> On Fri, May 20, 2022 at 05:25:56PM +0200, Daniel Lezcano wrote:
> > On 20/05/2022 17:02, Dan Carpenter wrote:
> > > This while loop exits with "i" set to -1 and so then it sets:
> >
> > Won't it exit with 'i' set to '0' ?
> >
>
> Wow. You made me worried there. I had to make a test case just to be
> sure:
>
> int i = 10;
>
> while (i--)
> printf("in %d\n", i);
> printf("out %d\n", i);
>
> Yep. Ends on on -1.
I wrote a blog about this a few days back.
https://staticthinking.wordpress.com/2022/05/17/i-or-i/
I really think the most readable way is to say:
while (--i >= 0)
derived_table[i] = derived_table[i + 1] - 300;
Some people like while (i--) because it works on unsigned variables but
that doesn't apply here and "unsigned int i;" is dumb.
regards,
dan carpenter
next prev parent reply other threads:[~2022-05-21 7:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-20 15:02 [PATCH] thermal: k3_j72xx_bandgap: Fix array underflow in prep_lookup_table() Dan Carpenter
2022-05-20 15:25 ` Daniel Lezcano
2022-05-21 6:56 ` Dan Carpenter
2022-05-21 7:04 ` Dan Carpenter [this message]
2022-07-28 15:41 ` [thermal: thermal/next] thermal/drivers/k3_j72xx_bandgap: " thermal-bot for Dan Carpenter
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