Messages in this thread Patch in this message | | | From | David Ahern <> | Subject | [PATCH] perf: detect loops processing events | Date | Wed, 8 May 2013 09:18:47 -0600 |
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Recovery algorithm in __perf_session__process_events attempts to remap a perf.data file with a different file_offset and try again at a new head position. Both of these adjustment rely on page_offset. If page_offset is 0 then file_offset and head never change which means the remap attempt is the same and the fetch_mmaped_event is the same and the processing just loops forever.
Detect this condition and warn the user.
Signed-off-by: David Ahern <dsahern@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Stephane Eranian <eranian@google.com> --- tools/perf/util/session.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index cf1fe01..1c4dc45 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1235,6 +1235,12 @@ more: } page_offset = page_size * (head / page_size); + /* catch looping where we never make forward progress. */ + if (page_offset == 0) { + pr_err("Loop detection processing events. Is file corrupted?\n"); + return -1; + } + file_offset += page_offset; head -= page_offset; goto remap; -- 1.7.10.1
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