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>

tools/perf/builtin-top.c

@@ -677,6 +677,12 @@ static void perf_event__process_sample(struct perf_tool *tool,
 		return;
 	}
 
+	if (!machine) {
+		pr_err("%u unprocessable samples recorded.",
+		       top->session->hists.stats.nr_unprocessable_samples++);
+		return;
+	}
+
 	if (event->header.misc & PERF_RECORD_MISC_EXACT_IP)
 		top->exact_samples++;
 

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 {

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))