perf evlist: Introduce control file descriptors

Define and initialize control file descriptors.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/0dd4f544-2610-96d6-1bdb-6582bdc3dc2c@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evlist.c

@@ -63,6 +63,9 @@ void evlist__init(struct evlist *evlist, struct perf_cpu_map *cpus,
 	perf_evlist__set_maps(&evlist->core, cpus, threads);
 	evlist->workload.pid = -1;
 	evlist->bkw_mmap_state = BKW_MMAP_NOTREADY;
+	evlist->ctl_fd.fd = -1;
+	evlist->ctl_fd.ack = -1;
+	evlist->ctl_fd.pos = -1;
 }
 
 struct evlist *evlist__new(void)

tools/perf/util/evlist.h

@@ -74,6 +74,11 @@ struct evlist {
 		pthread_t		th;
 		volatile int		done;
 	} thread;
+	struct {
+		int	fd;	/* control file descriptor */
+		int	ack;	/* ack file descriptor for control commands */
+		int	pos;	/* index at evlist core object to check signals */
+	} ctl_fd;
 };
 
 struct evsel_str_handler {