From: Jiri Olsa Date: Mon, 2 Jun 2014 17:44:23 +0000 (-0400) Subject: perf record: Fix poll return value propagation X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=a515114fa3cff8f1da10cd68914d55c10879c3e0;p=deliverable%2Flinux.git perf record: Fix poll return value propagation 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. Acked-by: Arnaldo Carvalho de Melo Acked-by: Namhyung Kim Cc: Arnaldo Carvalho de Melo Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1401732126-19465-1-git-send-email-jolsa@kernel.org Signed-off-by: Jiri Olsa --- diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index e4c85b8f46c2..ce2cfec5c764 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++; }