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Subject[tip:perf/core] perf inject: Copy events when reordering events in pipe mode
Commit-ID:  1e0d4f0200e4dbdfc38d818f329d8a0955f7c6f5
Gitweb: http://git.kernel.org/tip/1e0d4f0200e4dbdfc38d818f329d8a0955f7c6f5
Author: David Carrillo-Cisneros <davidcc@google.com>
AuthorDate: Mon, 10 Apr 2017 13:14:27 -0700
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 11 Apr 2017 15:23:41 -0300

perf inject: Copy events when reordering events in pipe mode

__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@vger.kernel.org.

$

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@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170410201432.24807-3-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
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 fe84df1..e70e935 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -79,7 +79,7 @@ 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);
}
@@ -150,6 +150,7 @@ 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;
}

int ordered_events__queue(struct ordered_events *oe, union perf_event *event,
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 24259bc2..a25302b 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1656,6 +1656,7 @@ 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));
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