perf machine: Fix the value used for unknown pids

The value used for unknown pids cannot be zero because that is used by
the "idle" task.

Use -1 instead.  Also handle the unknown pid case when creating map
groups.

Note that, threads with an unknown pid should not occur because fork (or
synthesized) events precede the thread's existence.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1405332185-4050-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index c38d06c..b7f555a 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -935,8 +935,8 @@
 		return -1;
 	}
 
-	sched_out = machine__findnew_thread(machine, 0, prev_pid);
-	sched_in = machine__findnew_thread(machine, 0, next_pid);
+	sched_out = machine__findnew_thread(machine, -1, prev_pid);
+	sched_in = machine__findnew_thread(machine, -1, next_pid);
 
 	out_events = thread_atoms_search(&sched->atom_root, sched_out, &sched->cmp_pid);
 	if (!out_events) {
@@ -979,7 +979,7 @@
 {
 	const u32 pid	   = perf_evsel__intval(evsel, sample, "pid");
 	const u64 runtime  = perf_evsel__intval(evsel, sample, "runtime");
-	struct thread *thread = machine__findnew_thread(machine, 0, pid);
+	struct thread *thread = machine__findnew_thread(machine, -1, pid);
 	struct work_atoms *atoms = thread_atoms_search(&sched->atom_root, thread, &sched->cmp_pid);
 	u64 timestamp = sample->time;
 	int cpu = sample->cpu;
@@ -1012,7 +1012,7 @@
 	struct thread *wakee;
 	u64 timestamp = sample->time;
 
-	wakee = machine__findnew_thread(machine, 0, pid);
+	wakee = machine__findnew_thread(machine, -1, pid);
 	atoms = thread_atoms_search(&sched->atom_root, wakee, &sched->cmp_pid);
 	if (!atoms) {
 		if (thread_atoms_insert(sched, wakee))
@@ -1072,7 +1072,7 @@
 	if (sched->profile_cpu == -1)
 		return 0;
 
-	migrant = machine__findnew_thread(machine, 0, pid);
+	migrant = machine__findnew_thread(machine, -1, pid);
 	atoms = thread_atoms_search(&sched->atom_root, migrant, &sched->cmp_pid);
 	if (!atoms) {
 		if (thread_atoms_insert(sched, migrant))
@@ -1290,7 +1290,7 @@
 		return -1;
 	}
 
-	sched_in = machine__findnew_thread(machine, 0, next_pid);
+	sched_in = machine__findnew_thread(machine, -1, next_pid);
 
 	sched->curr_thread[this_cpu] = sched_in;