linux-kernel - Re: [PATCH 12/12] perf report: Add --task option to display monitored tasks

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Message-ID: <20180109130524.GA30494@kernel.org>
Date:   Tue, 9 Jan 2018 10:05:24 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        kernel-team@....com
Subject: Re: [PATCH 12/12] perf report: Add --task option to display
 monitored tasks

Em Tue, Jan 09, 2018 at 10:15:51AM +0100, Jiri Olsa escreveu:
> On Tue, Jan 09, 2018 at 10:56:07AM +0900, Namhyung Kim wrote:
> 
> SNIP
> 
> > > +static struct task *task_list(struct task *task, struct machine *machine)
> > > +{
> > > +	struct thread *parent_thread, *thread = task->thread;
> > > +	struct task   *parent_task;
> > > +
> > > +	/* Already listed. */
> > > +	if (!list_empty(&task->list))
> > > +		return NULL;
> > > +
> > > +	/* Last one in the chain. */
> > > +	if (thread->ppid == -1)
> > > +		return task;
> > > +
> > > +	parent_thread = machine__findnew_thread(machine, -1, thread->ppid);
> > 
> > I think it should be machine__find_thread() since creating a new
> > thread at this stage would lack thread->priv anyway.
> 
> ugh, that's right.. I tried to stay safe, but the NULL
> in priv would bring it down anyway
> 
> Arnaldo,
> I already see changed version on top of your branch,
> please let me know if you make also this change or
> I should send v2

I can make the change, thanks!

Just to make sure we're on the same page, just this, right?

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 3685ac101b16..e60709fe31ed 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -633,9 +633,9 @@ static struct task *tasks_list(struct task *task, struct machine *machine)
 	if (thread->ppid == -1)
 		return task;
 
-	parent_thread = machine__findnew_thread(machine, -1, thread->ppid);
+	parent_thread = machine__find_thread(machine, -1, thread->ppid);
 	if (!parent_thread)
-		return ERR_PTR(-ENOMEM);
+		return ERR_PTR(-ENOENT);
 
 	parent_task = thread__priv(parent_thread);
 	list_add_tail(&task->list, &parent_task->children);