perf tools: Save parent pid in thread struct

Information is available, so why not save it in case some command wants
to use it.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1369543631-5106-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/thread.c

@@ -14,6 +14,7 @@ struct thread *thread__new(pid_t pid)
 	if (self != NULL) {
 		map_groups__init(&self->mg);
 		self->pid = pid;
+		self->ppid = -1;
 		self->comm = malloc(32);
 		if (self->comm)
 			snprintf(self->comm, 32, ":%d", self->pid);
@@ -82,5 +83,8 @@ int thread__fork(struct thread *self, struct thread *parent)
 	for (i = 0; i < MAP__NR_TYPES; ++i)
 		if (map_groups__clone(&self->mg, &parent->mg, i) < 0)
 			return -ENOMEM;
+
+	self->ppid = parent->pid;
+
 	return 0;
 }

tools/perf/util/thread.h

@@ -13,6 +13,7 @@ struct thread {
 	};
 	struct map_groups	mg;
 	pid_t			pid;
+	pid_t			ppid;
 	char			shortname[3];
 	bool			comm_set;
 	char			*comm;