[PATCH AUTOSEL for 3.18 40/63] perf inject: Copy events when reordering events in pipe mode

[Sasha Levin]

From: David Carrillo-Cisneros <davidcc@xxxxxxxxxx>

[ Upstream commit 1e0d4f0200e4dbdfc38d818f329d8a0955f7c6f5 ]

__perf_session__process_pipe_events reuses the same memory buffer to
process all events in the pipe.

When reordering is needed (e.g. -b option), events are not immediately
flushed, but kept around until reordering is possible, causing
memory corruption.

The problem is usually observed by a "Unknown sample error" output. It
can easily be reproduced by:

  perf record -o - noploop | perf inject -b > output

Committer testing:

Before:

  $ perf record -o - stress -t 2 -c 2 | perf inject -b > /dev/null
  stress: info: [8297] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
  stress: info: [8297] successful run completed in 2s
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  Warning:
  Found 1 unknown events!

  Is this an older tool processing a perf.data file generated by a more recent tool?

  If that is not the case, consider reporting to linux-kernel@xxxxxxxxxxxxxxxx

  $

After:

  $ perf record -o - stress -t 2 -c 2 | perf inject -b > /dev/null
  stress: info: [9027] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
  stress: info: [9027] successful run completed in 2s
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  no symbols found in /usr/bin/stress, maybe install a debug package?
  no symbols found in /usr/bin/stress, maybe install a debug package?
  $

Signed-off-by: David Carrillo-Cisneros <davidcc@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Simon Que <sque@xxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170410201432.24807-3-davidcc@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 tools/perf/util/ordered-events.c | 3 ++-
 tools/perf/util/session.c        | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index fd4be94125fb..e2c53bb0e476 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -80,7 +80,7 @@ static union perf_event *dup_event(struct ordered_events *oe,
 
 static void free_dup_event(struct ordered_events *oe, union perf_event *event)
 {
-	if (oe->copy_on_queue) {
+	if (event && oe->copy_on_queue) {
 		oe->cur_alloc_size -= event->header.size;
 		free(event);
 	}
@@ -151,6 +151,7 @@ void ordered_events__delete(struct ordered_events *oe, struct ordered_event *eve
 	list_move(&event->list, &oe->cache);
 	oe->nr_events--;
 	free_dup_event(oe, event->event);
+	event->event = NULL;
 }
 
 static int __ordered_events__flush(struct perf_session *s,
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 80dbba095f30..e798b58971bf 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1080,6 +1080,7 @@ static int __perf_session__process_pipe_events(struct perf_session *session,
 	buf = malloc(cur_size);
 	if (!buf)
 		return -errno;
+	ordered_events__set_copy_on_queue(oe, true);
 more:
 	event = buf;
 	err = readn(fd, event, sizeof(struct perf_event_header));
-- 
2.14.1