linux-kernel - [PATCH 2/5] perf record: Fix done

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Date:   Wed, 24 Aug 2022 10:28:11 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] perf record: Fix done_fd wakeup event

evlist__add_wakeup_eventfd() calls perf_evlist__add_pollfd() to add a
non-perf-event to the evlist pollfds. Since commit 415ccb58f68a
("perf record: Introduce thread specific data array") that doesn't work
because evlist pollfs is not polled and done_fd is not duplicated into
thread-data.

Patch "perf record: Fix way of handling non-perf-event pollfds" added a new
approach that ensures file descriptors like done_fd are handled correctly
by flagging them as fdarray_flag__non_perf_event.

Fix by flagging done_fd as fdarray_flag__non_perf_event.

Example:

 Before:

  $ sleep 3 & perf record -vv -p $!
  ...
  thread_data[0x55f44bd34140]: pollfd[0] <- event_fd=5
  thread_data[0x55f44bd34140]: pollfd[1] <- event_fd=6
  thread_data[0x55f44bd34140]: pollfd[2] <- event_fd=7
  thread_data[0x55f44bd34140]: pollfd[3] <- event_fd=8
  thread_data[0x55f44bd34140]: pollfd[4] <- event_fd=9
  thread_data[0x55f44bd34140]: pollfd[5] <- event_fd=10
  thread_data[0x55f44bd34140]: pollfd[6] <- event_fd=11
  thread_data[0x55f44bd34140]: pollfd[7] <- event_fd=12
  ...

 After:

  $ sleep 3 & perf record -vv -p $!
  ...
  thread_data[0x55a8ded89140]: pollfd[0] <- event_fd=5
  thread_data[0x55a8ded89140]: pollfd[1] <- event_fd=6
  thread_data[0x55a8ded89140]: pollfd[2] <- event_fd=7
  thread_data[0x55a8ded89140]: pollfd[3] <- event_fd=8
  thread_data[0x55a8ded89140]: pollfd[4] <- event_fd=9
  thread_data[0x55a8ded89140]: pollfd[5] <- event_fd=10
  thread_data[0x55a8ded89140]: pollfd[6] <- event_fd=11
  thread_data[0x55a8ded89140]: pollfd[7] <- event_fd=12
  thread_data[0x55a8ded89140]: pollfd[8] <- non_perf_event fd=4
  ...

This patch depends on "perf record: Fix way of handling non-perf-event
pollfds".

Fixes: 415ccb58f68a ("perf record: Introduce thread specific data array")
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/evlist.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 48167f3941a6..0b2222d05577 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -608,7 +608,8 @@ int evlist__filter_pollfd(struct evlist *evlist, short revents_and_mask)
 int evlist__add_wakeup_eventfd(struct evlist *evlist, int fd)
 {
 	return perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN,
-				       fdarray_flag__nonfilterable);
+				       fdarray_flag__nonfilterable |
+				       fdarray_flag__non_perf_event);
 }
 #endif
 
-- 
2.25.1