perf record: Implement control commands handling

Implement handling of 'enable' and 'disable' control commands coming
from control file descriptor.
Signed-off-by: NAlexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Acked-by: NNamhyung 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/f0fde590-1320-dca1-39ff-da3322704d3b@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -1564,6 +1564,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 	bool disabled = false, draining = false;
 	int fd;
 	float ratio = 0;
+	enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
 
 	atexit(record__sig_exit);
 	signal(SIGCHLD, sig_handler);
@@ -1883,6 +1884,21 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 				draining = true;
 		}
 
+		if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {
+			switch (cmd) {
+			case EVLIST_CTL_CMD_ENABLE:
+				pr_info(EVLIST_ENABLED_MSG);
+				break;
+			case EVLIST_CTL_CMD_DISABLE:
+				pr_info(EVLIST_DISABLED_MSG);
+				break;
+			case EVLIST_CTL_CMD_ACK:
+			case EVLIST_CTL_CMD_UNSUPPORTED:
+			default:
+				break;
+			}
+		}
+
 		/*
 		 * When perf is starting the traced process, at the end events
 		 * die with the process and we wait for that. Thus no need to