perf top: Don't process samples with no valid machine object

The perf sample processing code relies on a valid machine object. Make
sure that this path is only entered when such a object exists.

A counter for samples where no machine object exits is also introduced
to give the user a message about these samples.

Reported-by: David Ahern <dsahern@gmail.com>
Reported-by: Jason Wang <jasowang@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328893505-4115-2-git-send-email-joerg.roedel@amd.com
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 0d486135d10..48e5acd1e86 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -32,6 +32,7 @@ struct events_stats {
         u32 nr_unknown_events;
         u32 nr_invalid_chains;
         u32 nr_unknown_id;
+        u32 nr_unprocessable_samples;
 };
 
 enum hist_column {
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 552c1c50eea..9f833cf9c6a 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -796,6 +796,10 @@ static int perf_session_deliver_event(struct perf_session *session,
                         ++session->hists.stats.nr_unknown_id;
                         return -1;
                 }
+                if (machine == NULL) {
+                        ++session->hists.stats.nr_unprocessable_samples;
+                        return -1;
+                }
                 return tool->sample(tool, event, sample, evsel, machine);
         case PERF_RECORD_MMAP:
                 return tool->mmap(tool, event, sample, machine);
@@ -964,6 +968,12 @@ static void perf_session__warn_about_errors(const struct perf_session *session,
                             session->hists.stats.nr_invalid_chains,
                             session->hists.stats.nr_events[PERF_RECORD_SAMPLE]);
         }
+
+        if (session->hists.stats.nr_unprocessable_samples != 0) {
+                ui__warning("%u unprocessable samples recorded.\n"
+                            "Do you have a KVM guest running and not using 'perf kvm'?\n",
+                            session->hists.stats.nr_unprocessable_samples);
+        }
 }
 
 #define session_done()  (*(volatile int *)(&session_done))