perf kvm stat live: Enable events copying

Process of analyzing events caused by 2 functions: mmap_read() and
finished_round().

During mmap_read(), perf receives events from shared memory, queues
their pointers for further processing in finished_round() and notifies
the kernel that the events have been processed.

By the time when finished_round() is invoked, queued events can be
overwritten by the kernel, so the finished_round() occurs on potentially
corrupted memory.

Since there is no place where the event can be safely consumed, let's
copy events when queueing.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1412347212-28237-3-git-send-email-yarygin@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index ef9fc15fbfbfd60d63439877abcb72bf7113a17f..b65eb0507b38a97bb86b948eec3d6c045b5c27e1 100644 (file)
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1358,6 +1358,7 @@ static int kvm_events_live(struct perf_kvm_stat *kvm,
        }
        kvm->session->evlist = kvm->evlist;
        perf_session__set_id_hdr_size(kvm->session);
+       ordered_events__set_copy_on_queue(&kvm->session->ordered_events, true);
        machine__synthesize_threads(&kvm->session->machines.host, &kvm->opts.target,
                                    kvm->evlist->threads, false);
        err = kvm_live_open_events(kvm);