Messages in this thread Patch in this message | | | From | Alexander Yarygin <> | Subject | [PATCH 2/2] perf kvm stat live: Enable events copying | Date | Thu, 2 Oct 2014 14:32:09 +0400 |
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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: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> --- tools/perf/builtin-kvm.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c index f5d3ae4..80efbfa 100644 --- a/tools/perf/builtin-kvm.c +++ b/tools/perf/builtin-kvm.c @@ -1370,6 +1370,7 @@ 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); -- 1.9.1
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