Subject: Re: [PATCH 1/4] ftrace: Fix MATCH_END_ONLY filter matching
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Riss <frederic.riss@gmail.com>, Li Zefan <lizf@cn.fujitsu.com>,
       Ingo Molnar <mingo@elte.hu>, Wenji Huang <wenji.huang@oracle.com>,
       LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <20091211122721.GH5244@nowhere>
References: <4B2217D0.5000308@cn.fujitsu.com>
	 <87d3b2040912110420w270cff7ew36a7f2389a88fdb9@mail.gmail.com>
	 <20091211122721.GH5244@nowhere>
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Organization: Kihon Technologies Inc.
Date: Fri, 11 Dec 2009 10:10:31 -0500
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On Fri, 2009-12-11 at 13:27 +0100, Frederic Weisbecker wrote:
> On Fri, Dec 11, 2009 at 01:20:04PM +0100, Frederic Riss wrote:
> > 2009/12/11 Li Zefan <lizf@cn.fujitsu.com>:
> > > For '*foo' pattern, we should allow any string ending with
> > > 'foo', but ftrace filter incorrectly disallows strings
> > > like bar_foo_foo:
> > [...]
> > >        case MATCH_END_ONLY:
> > > -               ptr = strstr(str, regex);
> > > -               if (ptr && (ptr[len] == 0))
> > > +               slen = strlen(str);
> > > +               if (slen >= len && memcpy(str + slen - len, regex, len))
> > >                        matched = 1;
> > 
> > Shouldn't that be memcmp() == 0? I don't see how memcpy might serve as
> > a compare operator.
> > 
> > Fred.
> 
> 
> Oh you're right, I reviewed it too quickly. Perhaps the star's
> alignment made it possible for only one Frederic to review it
> the right way...
> 

The stars are still fuzzy to me. How does memcpy work here?

-- Steve


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