linux-kernel - Re: [PATCH v2] video: fbdev: uvesafb.c: Added additional error checking

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Message-ID: <20140724173112.GA2015@udknight>
Date:	Fri, 25 Jul 2014 01:31:12 +0800
From:	Wang YanQing <udknight@...il.com>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jingoo Han <jg1.han@...sung.com>,
	David Fries <David@...es.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Joe Perches <joe@...ches.com>, linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] video: fbdev: uvesafb.c:  Added additional error
 checking

On Wed, Jul 23, 2014 at 11:20:27PM +0200, Rickard Strandqvist wrote:
> Variable was assigned a value that is never used.
> Now the variable is used, and the function returns if a call to
> uvesafb_exec() returns a error.

Because the only user of uvesafb_vbe_getpmi in uvesafb.c
don't check its return value, it should do the check indeed,
so maybe below change is better:

-       if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
+       if (err || (task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
                par->pmi_setpal = par->ypan = 0;
        }

Or we check uvesafb_vbe_getpmi's return value, then the code will looks like below:

if (uvesafb_vbe_getpmi(task, par))
    par->pmi_setpal = par->ypan = 0;


Thanks.
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