linux-kernel - Re: [PATCH 4/5] kernel/debug/kdb/kdb_bp.c: drop negativity check on unsigned value

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Message-ID: <20140722074721.GM25880@mwanda>
Date:	Tue, 22 Jul 2014 10:47:21 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Andrey Utkin <andrey.krieger.utkin@...il.com>
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
	kgdb-bugreport@...ts.sourceforge.net, dcb314@...mail.com,
	jason.wessel@...driver.com
Subject: Re: [PATCH 4/5] kernel/debug/kdb/kdb_bp.c: drop negativity check on
 unsigned value

On Fri, Jul 18, 2014 at 06:34:52PM +0300, Andrey Utkin wrote:
>  static char *kdb_bptype(kdb_bp_t *bp)
>  {
> -	if (bp->bp_type < 0 || bp->bp_type > 4)
> +	if (bp->bp_type > 4)
>  		return "";

With Smatch, I ignore negative checks in this format.  It's obvious what
the intent is and they are harmless.  Patching them requires a little
review to make sure that someone isn't introducing a bug and can't be
done directly in the email client.

On the other hand, in Smatch I do complain about checks like:

	if (bp->bp_type > 4 || bp->bp_type < 0)

Because only backwards thinking people write checks like that.

regards,
dan carpenter

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