[tip:perf/urgent] perf evlist: Fix side band thread draining

[tip-bot for Jiri Olsa]

Commit-ID:  adc6257c4a6f23ff97dca8314fcd33828e2d8db5
Gitweb:     https://git.kernel.org/tip/adc6257c4a6f23ff97dca8314fcd33828e2d8db5
Author:     Jiri Olsa <jo...@kernel.org>
AuthorDate: Tue, 16 Apr 2019 18:01:23 +0200
Committer:  Arnaldo Carvalho de Melo <a...@redhat.com>
CommitDate: Wed, 17 Apr 2019 14:30:11 -0300

perf evlist: Fix side band thread draining

Current perf_evlist__poll_thread() code could finish without draining
the data. Adding the logic that makes sure we won't finish before the
drain.

Signed-off-by: Jiri Olsa <jo...@kernel.org>
Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Song Liu <songliubrav...@fb.com>
Fixes: 657ee5531903 ("perf evlist: Introduce side band thread")
Link: http://lkml.kernel.org/r/20190416160127.30203-9-jo...@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
 tools/perf/util/evlist.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 6689378ee577..51ead577533f 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1868,12 +1868,12 @@ static void *perf_evlist__poll_thread(void *arg)
 {
        struct perf_evlist *evlist = arg;
        bool draining = false;
-       int i;
+       int i, done = 0;
+
+       while (!done) {
+               bool got_data = false;
 
-       while (draining || !(evlist->thread.done)) {
-               if (draining)
-                       draining = false;
-               else if (evlist->thread.done)
+               if (evlist->thread.done)
                        draining = true;
 
                if (!draining)
@@ -1894,9 +1894,13 @@ static void *perf_evlist__poll_thread(void *arg)
                                        pr_warning("cannot locate proper evsel 
for the side band event\n");
 
                                perf_mmap__consume(map);
+                               got_data = true;
                        }
                        perf_mmap__read_done(map);
                }
+
+               if (draining && !got_data)
+                       break;
        }
        return NULL;
 }