linux-kernel - Re: [PATCH] perf-record: Check correct pid when forking

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Message-ID: <20100531214015.GA27050@liondog.tnic>
Date:	Mon, 31 May 2010 23:40:15 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf-record: Check correct pid when forking

From: Frederic Weisbecker <fweisbec@...il.com>
Date: Mon, May 31, 2010 at 11:27:26PM +0200

Hi Frederic :),

> On Mon, May 31, 2010 at 11:18:18PM +0200, Borislav Petkov wrote:
> > When forking the child to be traced, we should check the correct return
> > value from fork() and not a local variable which is otherwise unused.
> > 
> > Signed-off-by: Borislav Petkov <bp@...en8.de>
> > ---
> >  tools/perf/builtin-record.c |    3 +--
> >  1 files changed, 1 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index 9bc8905..dc3435e 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -503,7 +503,6 @@ static int __cmd_record(int argc, const char **argv)
> >  {
> >  	int i, counter;
> >  	struct stat st;
> > -	pid_t pid = 0;
> >  	int flags;
> >  	int err;
> >  	unsigned long waking = 0;
> > @@ -572,7 +571,7 @@ static int __cmd_record(int argc, const char **argv)
> >  
> >  	if (forks) {
> >  		child_pid = fork();
> > -		if (pid < 0) {
> > +		if (child_pid < 0) {
> 
> 
> 
> Oops :)

Yeah, this looked really odd and I had recheck it couple of times just
to be sure I'm not missing any "hidden" semantics. And it seems that
nobody has hit that because obviously we always fork fine :)

-- 
Regards/Gruss,
    Boris.
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