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Date: Tue, 12 May 2015 00:26:47 +0900
From: Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH 4/6] perf kmem: Print gfp flags in human readable string
Message-ID: <20150511152647.GB12220@danjae.kornet>
References: <1429592107-1807-1-git-send-email-namhyung@kernel.org>
 <1429592107-1807-5-git-send-email-namhyung@kernel.org>
 <20150511143536.GP28183@kernel.org>
 <20150511144110.GR28183@kernel.org>
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To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Jiri Olsa <jolsa@redhat.com>, LKML <linux-kernel@vger.kernel.org>, David Ahern <dsahern@gmail.com>, Joonsoo Kim <js1304@gmail.com>, Minchan Kim <minchan@kernel.org>, Pekka Enberg <penberg@kernel.org>, linux-mm@kvack.org

On Mon, May 11, 2015 at 11:41:10AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, May 11, 2015 at 11:35:36AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Tue, Apr 21, 2015 at 01:55:05PM +0900, Namhyung Kim escreveu:
> > > Save libtraceevent output and print it in the header.
> > 
> > <SNIP>
> > 
> > > +static int parse_gfp_flags(struct perf_evsel *evsel, struct perf_sample *sample,
> > > +			   unsigned int gfp_flags)
> > > +{
> > > +	char *str, *pos;
> 
> > > +	str = strtok_r(seq.buffer, " ", &pos);
> > 
> > builtin-kmem.c:743:427: error: a??posa?? may be used uninitialized in this
> > function [-Werror=maybe-uninitialized]
> >     new->human_readable = strdup(str + 10);
> >                                                                                                                                                                                                                                                                                                                                                                                                                                            ^
> > builtin-kmem.c:716:14: note: a??posa?? was declared here
> >   char *str, *pos;
> >               ^
> 
> Emphasis on the "may", as according to strtok_r your code is ok, its
> just the compiler that needs to be told that no, it is not being
> accessed uninitialized:
> 
> <quote man strtok>
>        On the first call to strtok_r(), str should point to the string
> to be parsed, and the value of saveptr is ignored.  In subsequent calls,
> str should be NULL, and saveptr should be unchanged since the previous
> call.
> </>
> 
> So just setting it to NULL is enough.

Agreed.

Thanks for fixing this,
Namhyung

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