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Subject[PATCH 01/16] perf session: Fail on processing event with unknown size
Date
From: Jiri Olsa <jolsa@redhat.com>

Currently if we cannot decide the size of the event, we guess next
event possition by:
"... check alignment, and increment a single u64 in the hope
to catch on again 'soon'"

This usually ends up with segfault or endless loop. It's better
to admit the failure right away, then pretend nothing happened.
It makes the life easier ;)

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120416184251.GA11503@m.brq.redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/session.c | 30 +++++++++---------------------
1 file changed, 9 insertions(+), 21 deletions(-)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 9412e3b..f992ae3 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1100,16 +1100,10 @@ more:
}

if ((skip = perf_session__process_event(self, &event, tool, head)) < 0) {
- dump_printf("%#" PRIx64 " [%#x]: skipping unknown header type: %d\n",
- head, event.header.size, event.header.type);
- /*
- * assume we lost track of the stream, check alignment, and
- * increment a single u64 in the hope to catch on again 'soon'.
- */
- if (unlikely(head & 7))
- head &= ~7ULL;
-
- size = 8;
+ pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
+ head, event.header.size, event.header.type);
+ err = -EINVAL;
+ goto out_err;
}

head += size;
@@ -1218,17 +1212,11 @@ more:

if (size == 0 ||
perf_session__process_event(session, event, tool, file_pos) < 0) {
- dump_printf("%#" PRIx64 " [%#x]: skipping unknown header type: %d\n",
- file_offset + head, event->header.size,
- event->header.type);
- /*
- * assume we lost track of the stream, check alignment, and
- * increment a single u64 in the hope to catch on again 'soon'.
- */
- if (unlikely(head & 7))
- head &= ~7ULL;
-
- size = 8;
+ pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
+ file_offset + head, event->header.size,
+ event->header.type);
+ err = -EINVAL;
+ goto out_err;
}

head += size;
--
1.7.9.2.358.g22243


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