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Groups > linux.kernel > #1343973

[PATCH 35/46] 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 overwrite ring
buffer 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 92eccf1..120b3bb 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -462,6 +462,19 @@ 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;
@@ -472,7 +485,7 @@ 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 00/46] perf tools: Fix and improvements (bpf and overwrite) Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
  [PATCH 07/46] perf trace: Print content of bpf-output event Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
    [tip:perf/core] perf trace: Print content of bpf-output event tip-bot for Wang Nan <tipbot@zytor.com> - 2016-02-27 10:50 +0100
  [PATCH 43/46] perf record: Rename variable to make code clear Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
  [PATCH 46/46] perf tools: Don't warn about out of order event if write_backward is used Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 26/46] perf record: Disable buildid cache options by default in switch output mode Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 33/46] perf tools: Operate multiple channels Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 24/46] perf record: Split output into multiple files via '--switch-output' Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 45/46] perf record: Allow generate tracking events at the end of output Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 36/46] perf record: Don't poll on overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 30/46] perf record: Prevent reading invalid data in record__mmap_read Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 31/46] perf tools: Add evlist channel helpers Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 35/46] perf record: Don't read from and poll overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 23/46] perf record: Add '--timestamp-filename' option to append timestamp to output filename Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 25/46] perf record: Force enable --timestamp-filename when --switch-output is provided Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 28/46] perf record: Generate tracking events for process forked by perf Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 21/46] perf record: Turns auxtrace_snapshot_enable into 3 states Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 27/46] perf record: Re-synthesize tracking events after output switching Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
  [PATCH 12/46] perf core: Prepare writing into ring buffer from end Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 19/46] perf record: Extract synthesize code to record__synthesize() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 11/46] perf core: Set event's default overflow_handler Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 13/46] perf core: Add backward attribute to perf event Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 18/46] perf record: Use WARN_ONCE to replace 'if' condition Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 20/46] perf tools: Add perf_data_file__switch() helper Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 17/46] perf tools: Make ordered_events reusable Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 14/46] perf core: Reduce perf event output overhead by new overflow handler Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 08/46] perf data: Support converting data from bpf_perf_event_output() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 10/46] perf core: Introduce new ioctl options to pause and resume ring buffer Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
    Re: [PATCH 10/46] perf core: Introduce new ioctl options to pause  and resume ring buffer Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-02-29 16:40 +0100
      Re: [PATCH 10/46] perf core: Introduce new ioctl options to pause and  resume ring buffer "Wangnan (F)" <wangnan0@huawei.com> - 2016-03-03 03:20 +0100
  [PATCH 09/46] perf data: Explicitly set byte order for integer types Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
  [PATCH 03/46] perf config: Bring perf_default_config to the very beginning at main() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
    [tip:perf/core] perf config: Bring perf_default_config to the very  beginning at main() tip-bot for Wang Nan <tipbot@zytor.com> - 2016-02-27 10:50 +0100

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