trace-cmd report: Add --first-event and --last-event options

Add the options to trace-cmd report to show the timestamp of the first and
last events.

This also fixes a memory leak when --cpus is used, but was not a major
issue as the code exited immediately afterward.

Link: https://lore.kernel.org/linux-trace-devel/20220607122242.51bf5aa2@gandalf.local.home

Suggested-by: Julia Lawall <julia.lawall@inria.fr>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216068
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

3 files changed, 58 insertions, 6 deletions

diff --git a/Documentation/trace-cmd/trace-cmd-report.1.txt b/Documentation/trace-cmd/trace-cmd-report.1.txt
index aad8ab51..cf5c88b2 100644
--- a/Documentation/trace-cmd/trace-cmd-report.1.txt
+++ b/Documentation/trace-cmd/trace-cmd-report.1.txt
@@ -254,6 +254,12 @@ OPTIONS
 *--cpus*::
     List the CPUs that have data in the trace file then exit.
 
+*--first-event*::
+    Show the timestamp of the first event of all CPUs that have data.
+
+*--last-event*::
+    Show the timestamp of the last event of all CPUs that have data.
+
 *--stat*::
     If the trace.dat file recorded the final stats (outputed at the end of record)
     the *--stat* option can be used to retrieve them.
diff --git a/tracecmd/trace-read.c b/tracecmd/trace-read.c
index df559d2a..691450b0 100644
--- a/tracecmd/trace-read.c
+++ b/tracecmd/trace-read.c
@@ -157,7 +157,8 @@ static void print_event_name(struct trace_seq *s, struct tep_event *event)
 
 enum time_fmt {
 	TIME_FMT_LAT		= 1,
-	TIME_FMT_NORMAL		= 2,
+	TIME_FMT_NORMAL,
+	TIME_FMT_TS,
 };
 
 static const char *time_format(struct tracecmd_input *handle, enum time_fmt tf)
@@ -172,11 +173,11 @@ static const char *time_format(struct tracecmd_input *handle, enum time_fmt tf)
 	default:
 		if (tracecmd_get_flags(handle) & TRACECMD_FL_IN_USECS) {
 			if (tep_test_flag(tep, TEP_NSEC_OUTPUT))
-				return " %9.1d:";
+				return tf == TIME_FMT_NORMAL ? " %9.1d:" : "%9.1d";
 			else
-				return " %6.1000d:";
+				return tf == TIME_FMT_NORMAL ? " %6.1000d:" : "%6.1000d";
 		} else
-			return "%12d:";
+			return tf == TIME_FMT_NORMAL ? "%12d:" : "%12d";
 	}
 }
 
@@ -1507,6 +1508,19 @@ static void set_event_flags(struct tep_handle *pevent, struct event_str *list,
 	}
 }
 
+static void show_event_ts(struct tracecmd_input *handle,
+			  struct tep_record *record)
+{
+	const char *tfmt = time_format(handle, TIME_FMT_TS);
+	struct tep_handle *tep = tracecmd_get_tep(handle);
+	struct trace_seq s;
+
+	trace_seq_init(&s);
+	tep_print_event(tep, &s, record, tfmt, TEP_PRINT_TIME);
+	printf("%s", s.buffer);
+	trace_seq_destroy(&s);
+}
+
 static void add_hook(const char *arg)
 {
 	struct hook_list *hook;
@@ -1543,6 +1557,8 @@ enum {
 	OPT_events	= 254,
 	OPT_cpu		= 255,
 	OPT_cpus	= 256,
+	OPT_first	= 257,
+	OPT_last	= 258,
 };
 
 void trace_report (int argc, char **argv)
@@ -1571,6 +1587,8 @@ void trace_report (int argc, char **argv)
 	int show_version = 0;
 	int show_events = 0;
 	int show_cpus = 0;
+	int show_first = 0;
+	int show_last = 0;
 	int print_events = 0;
 	int nanosec = 0;
 	int no_date = 0;
@@ -1601,6 +1619,7 @@ void trace_report (int argc, char **argv)
 			{"events", no_argument, NULL, OPT_events},
 			{"event", required_argument, NULL, OPT_event},
 			{"filter-test", no_argument, NULL, 'T'},
+			{"first-event", no_argument, NULL, OPT_first},
 			{"kallsyms", required_argument, NULL, OPT_kallsyms},
 			{"pid", required_argument, NULL, OPT_pid},
 			{"comm", required_argument, NULL, OPT_comm},
@@ -1610,6 +1629,7 @@ void trace_report (int argc, char **argv)
 			{"stat", no_argument, NULL, OPT_stat},
 			{"boundary", no_argument, NULL, OPT_boundary},
 			{"debug", no_argument, NULL, OPT_debug},
+			{"last-event", no_argument, NULL, OPT_last},
 			{"profile", no_argument, NULL, OPT_profile},
 			{"uname", no_argument, NULL, OPT_uname},
 			{"version", no_argument, NULL, OPT_version},
@@ -1754,6 +1774,14 @@ void trace_report (int argc, char **argv)
 		case OPT_stat:
 			show_stat = 1;
 			break;
+		case OPT_first:
+			show_first = 1;
+			show_cpus = 1;
+			break;
+		case OPT_last:
+			show_last = 1;
+			show_cpus = 1;
+			break;
 		case OPT_boundary:
 			/* Debug to look at buffer breaks */
 			buffer_breaks = 1;
@@ -1923,6 +1951,7 @@ void trace_report (int argc, char **argv)
 		}
 
 		if (show_cpus) {
+			struct tep_record *record;
 			int cpus;
 			int ret;
 			int i;
@@ -1935,8 +1964,23 @@ void trace_report (int argc, char **argv)
 			cpus = tracecmd_cpus(handle);
 			printf("List of CPUs in %s with data:\n", inputs->file);
 			for (i = 0; i < cpus; i++) {
-				if (tracecmd_read_cpu_first(handle, i))
-					printf("  %d\n", i);
+				if ((record = tracecmd_read_cpu_first(handle, i))) {
+					printf("  %d", i);
+					if (show_first) {
+						printf("\tFirst event:");
+						show_event_ts(handle, record);
+					}
+					if (show_last) {
+						tracecmd_free_record(record);
+						record = tracecmd_read_cpu_last(handle, i);
+						if (record) {
+							printf("\tLast event:");
+							show_event_ts(handle, record);
+						}
+					}
+					tracecmd_free_record(record);
+					printf("\n");
+				}
 			}
 			continue;
 		}
diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
index 2cfa64f5..abf6c3ac 100644
--- a/tracecmd/trace-usage.c
+++ b/tracecmd/trace-usage.c
@@ -230,6 +230,8 @@ static struct usage_help usage_help[] = {
 		"          --cpu <cpu1,cpu2,...> - filter events according to the given cpu list.\n"
 		"                                  A range of CPUs can be specified using 'cpuX-cpuY' notation.\n"
 		"          --cpus - List the CPUs that have content in it then exit.\n"
+		"          --first-event - Show the timestamp of the first event for all CPUs.\n"
+		"          --last-event - Show the timestamp of the last event for all CPUs.\n"
 		"          --check-events return whether all event formats can be parsed\n"
 		"          --stat - show the buffer stats that were reported at the end of the record.\n"
 		"          --uname - show uname of the record, if it was saved\n"