perf sched: Do not delete session object prematurely
Jiri Olsa [Mon, 8 Aug 2011 21:03:34 +0000 (23:03 +0200)]
The session object is released prematurely when processing events for
latency command. The session's thread objects are used within the
output_lat_thread function.

Runnning following commands:

 # perf sched record
 # perf sched latency

the latter displays incorrect data and might cause access violation.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1312837414-3819-1-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-sched.c

index dcfe887..3d5702c 100644 (file)
@@ -1637,23 +1637,29 @@ static struct perf_event_ops event_ops = {
        .ordered_samples        = true,
 };
 
-static int read_events(void)
+static void read_events(bool destroy, struct perf_session **psession)
 {
        int err = -EINVAL;
        struct perf_session *session = perf_session__new(input_name, O_RDONLY,
                                                         0, false, &event_ops);
        if (session == NULL)
-               return -ENOMEM;
+               die("No Memory");
 
        if (perf_session__has_traces(session, "record -R")) {
                err = perf_session__process_events(session, &event_ops);
+               if (err)
+                       die("Failed to process events, error %d", err);
+
                nr_events      = session->hists.stats.nr_events[0];
                nr_lost_events = session->hists.stats.total_lost;
                nr_lost_chunks = session->hists.stats.nr_events[PERF_RECORD_LOST];
        }
 
-       perf_session__delete(session);
-       return err;
+       if (destroy)
+               perf_session__delete(session);
+
+       if (psession)
+               *psession = session;
 }
 
 static void print_bad_events(void)
@@ -1689,9 +1695,10 @@ static void print_bad_events(void)
 static void __cmd_lat(void)
 {
        struct rb_node *next;
+       struct perf_session *session;
 
        setup_pager();
-       read_events();
+       read_events(false, &session);
        sort_lat();
 
        printf("\n ---------------------------------------------------------------------------------------------------------------\n");
@@ -1717,6 +1724,7 @@ static void __cmd_lat(void)
        print_bad_events();
        printf("\n");
 
+       perf_session__delete(session);
 }
 
 static struct trace_sched_handler map_ops  = {
@@ -1731,7 +1739,7 @@ static void __cmd_map(void)
        max_cpu = sysconf(_SC_NPROCESSORS_CONF);
 
        setup_pager();
-       read_events();
+       read_events(true, NULL);
        print_bad_events();
 }
 
@@ -1744,7 +1752,7 @@ static void __cmd_replay(void)
 
        test_calibrations();
 
-       read_events();
+       read_events(true, NULL);
 
        printf("nr_run_events:        %ld\n", nr_run_events);
        printf("nr_sleep_events:      %ld\n", nr_sleep_events);