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Date: Mon, 9 Dec 2013 14:23:50 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Namhyung Kim <namhyung@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Namhyung Kim <namhyung.kim@lge.com>
Subject: Re: [PATCH 01/14] tools lib traceevent: Get rid of malloc_or_die()
 in show_error()
Message-ID: <20131209142350.5d23108c@gandalf.local.home>
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On Mon, 9 Dec 2013 16:14:39 -0300
Arnaldo Carvalho de Melo <acme@ghostprotocols.net> wrote:

> Em Mon, Dec 09, 2013 at 02:03:42PM -0500, Steven Rostedt escreveu:
> > On Mon, 9 Dec 2013 15:30:09 -0300
> > Arnaldo Carvalho de Melo <acme@ghostprotocols.net> wrote:
> > 
> > 
> > > > +		error = malloc(MAX_ERR_STR_SIZE);
> > > > +		if (error == NULL) {
> > > > +			/* no memory */
> > > > +			*error_str = "failed to allocate memory";
> > > > +			return;
> > > 
> > > Can *error_str point to either malloc'ed or constant strings? Who
> > > releases the allocated memory?
> > > 
> > 
> > Good question. Perhaps we should have a flag that states if the string
> > is allocated or not. Or better yet, since the only reason it would be
> > pointing to a static string is if the string for error_str itself
> > failed to allocate. Then we could use a string within pevent for it:
> > 
> > static char *pevent_failed_error_alloc = "failed to allocate memory";
> > 
> > Then in the freeing of error str:
> > 
> > void pevent_free_error_str(error_str)
> > {
> > 	if (error_str != pevent_failed_error_alloc)
> > 		free(error_str);
> > }
> 
> That is a possibility, yes, then any other routine that works in such a
> way could check against this string, but what is wrong with returning a
> value to that function and checking against < 0?

Then everyone has to check if show_error() failed. Then report a bug if
it did. Egad, then we need to check if that error function failed, and
then that one and that one and that one :-)

-- Steve