If the perf record command is interrupted in record__mmap_read_all function, the 'done' is set and err has the latest poll return value, which is most likely positive number (= number of pollfds ready to read).
This 'positive err' is then propagated to the exit code, resulting in not finishing the perf.data header properly, causing following error in report: # perf record -F 50000 -a --- make the system real busy, so there's more chance to interrupt perf in event writing code --- ^C[ perf record: Woken up 16 times to write data ] [ perf record: Captured and wrote 30.292 MB perf.data (~1323468 samples) ] # perf report --stdio > /dev/null WARNING: The perf.data file's data size field is 0 which is unexpected. Was the 'perf record' command properly terminated? Fixing this by checking for positive poll return value and setting err to 0. Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Corey Ashford <[email protected]> Cc: David Ahern <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Jiri Olsa <[email protected]> --- tools/perf/builtin-record.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index e4c85b8..ce2cfec 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -454,7 +454,11 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) if (done) break; err = poll(rec->evlist->pollfd, rec->evlist->nr_fds, -1); - if (err < 0 && errno == EINTR) + /* + * Propagate error, only if there's any. Ignore positive + * number of returned events and interrupt error. + */ + if (err > 0 || (err < 0 && errno == EINTR)) err = 0; waking++; } -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
