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

From: Sasha Levin
Date: Sat Mar 03 2018 - 17:48:38 EST


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