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Groups > linux.kernel > #1400574

[PATCH 07/17] perf record: Don't read from and poll overwrite channel

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Reading from overwritable ring buffer is unreliable. Introduce
record__mmap_should_read() and prevent reading from such ring
buffers in 'perf record'. The rule in record__mmap_should_read() will
be changed when perf support reading from backward writing ring buffer.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: He Kuang <hekuang@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
 tools/perf/builtin-record.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 5e87602..d9a92e0 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -429,6 +429,19 @@ static struct perf_event_header finished_round_event = {
 	.type = PERF_RECORD_FINISHED_ROUND,
 };
 
+static bool record__mmap_should_read(struct record *rec, int idx)
+{
+	int channel = -1;
+
+	if (!rec->evlist->mmap[idx].base)
+		return false;
+	if (perf_evlist__channel_idx(rec->evlist, &channel, &idx))
+		return false;
+	if (perf_evlist__channel_check(rec->evlist, channel, RDONLY))
+		return false;
+	return true;
+}
+
 static int record__mmap_read_all(struct record *rec)
 {
 	u64 bytes_written = rec->bytes_written;
@@ -439,7 +452,7 @@ static int record__mmap_read_all(struct record *rec)
 	for (i = 0; i < total_mmaps; i++) {
 		struct auxtrace_mmap *mm = &rec->evlist->mmap[i].auxtrace_mmap;
 
-		if (rec->evlist->mmap[i].base) {
+		if (record__mmap_should_read(rec, i)) {
 			if (record__mmap_read(rec, i) != 0) {
 				rc = -1;
 				goto out;
-- 
1.8.3.4

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[PATCH 00/17] perf tools: Support overwritable ring buffer Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 15/17] perf record: Read from backward ring buffer Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read() Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read() Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
  [PATCH 09/17] perf tools: Detect avalibility of write_backward Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
      Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-20 17:40 +0200
        Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-20 17:40 +0200
  [PATCH 05/17] perf record: Prevent reading invalid data in record__mmap_read Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 17/17] perf tools: Don't warn about out of order event if write_backward is used Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 11/17] perf tools: Set write_backward attribut bit for overwrite events Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 04/17] perf tools: Operate multiple channels Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 08/17] perf record: Don't poll on overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 08/17] perf record: Don't poll on overwrite channel Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:20 +0200
      Re: [PATCH 08/17] perf record: Don't poll on overwrite channel "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-16 05:20 +0200
  [PATCH 16/17] perf record: Toggle overwrite ring buffer for reading Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 10/17] perf tools: Enable overwrite settings Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 10/17] perf tools: Enable overwrite settings Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-16 15:40 +0200
  [PATCH 07/17] perf record: Don't read from and poll overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 12/17] perf tools: Record fd into perf_mmap Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 13/17] perf tools: Add API to pause a channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 14/17] perf record: Rename variable to make code clear Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:10 +0200
  [PATCH 02/17] perf tools: Add evlist channel helpers Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:10 +0200
    Re: [PATCH 02/17] perf tools: Add evlist channel helpers Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
      Re: [PATCH 02/17] perf tools: Add evlist channel helpers "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-18 05:40 +0200
        Re: [PATCH 02/17] perf tools: Add evlist channel helpers Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> - 2016-05-18 15:30 +0200
  [PATCH 03/17] perf tools: Automatically add new channel according to evlist Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:20 +0200
  [PATCH 06/17] perf tools: Squash overwrite setting into channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:20 +0200

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