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Date:   Fri, 22 Apr 2022 13:23:03 +0100
From:   Aaron Tomlin <atomlin@redhat.com>
To:     Christoph Lameter <cl@gentwo.de>
Cc:     Oleksandr Natalenko <oleksandr@natalenko.name>, mcgrof@kernel.org,
        pmladek@suse.com, mbenes@suse.cz, christophe.leroy@csgroup.eu,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-modules@vger.kernel.org, atomlin@atomlin.com,
        ghalat@redhat.com, neelx@redhat.com
Subject: Re: [PATCH v3 2/2] module: Introduce module unload taint tracking
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On Fri 2022-04-22 10:11 +0200, Christoph Lameter wrote:
> On Thu, 21 Apr 2022, Aaron Tomlin wrote:
> 
> > > > +		if (len == strlen(mod->name) && !memcmp(mod_taint->name, mod->name, len) &&
> > >
> > > Here, two strings are compared, so I'd expect to see `strncmp()` instead of `memcmp()`.
> >
> > Good point. There are other examples of this throughout
> > kernel/module/main.c; albeit, I will use strncmp() here.
> 
> Comparing the length first may be an attempt to avoid the expensive
> memcmp. But here we need to first execute strlen() to obtain the string
> length. This is already accessing all characters so this
> check is wasteful and a straight str[n]cmp is better.

Hi Christoph,

Agreed - we can skip the extra strlen().

Thanks,

-- 
Aaron Tomlin