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[PATCH 13/29] perf record: Force ignore_missing_thread for uid option

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From: Jiri Olsa <jolsa@kernel.org>

Enable perf_evsel::ignore_missing_thread for -u option to ignore
complete failure if any of the user's processes die between its
enumeration and time we open the event.

Committer notes:

While doing a 'make -j4 allmodconfig' we sometimes get into the race:

Before:

  # perf record -u acme
  Error:
  The sys_perf_event_open() syscall returned with 3 (No such process) for event (cycles:ppp).
  /bin/dmesg may provide additional information.
  No CONFIG_PERF_EVENTS=y kernel support configured?
  #

After:

  [root@jouet ~]# perf record -u acme
  WARNING: Ignored open failure for pid 9888
  WARNING: Ignored open failure for pid 18059
  [root@jouet ~]#

Which is an improvement, with the races not preventing the remaining threads
for the specified user from being monitored, but the message probably needs
further clarification.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1481538943-21874-6-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-record.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index fa26865364b6..74d6a035133a 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1687,6 +1687,9 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 		goto out;
 	}
 
+	/* Enable ignoring missing threads when -u option is defined. */
+	rec->opts.ignore_missing_thread = rec->opts.target.uid != UINT_MAX;
+
 	err = -ENOMEM;
 	if (perf_evlist__create_maps(rec->evlist, &rec->opts.target) < 0)
 		usage_with_options(record_usage, record_options);
-- 
2.9.3

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[GIT PULL 00/29] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:10 +0100
  [PATCH 13/29] perf record: Force ignore_missing_thread for uid option Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 06/29] perf sched timehist: Add -I/--idle-hist option Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 21/29] perf trace: Check if MAP_32BIT is defined (again) Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 05/29] perf sched timehist: Skip non-idle events when necessary Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 07/29] perf sched timehist: Show callchains for idle stat Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 09/29] perf mem: Fix --all-user/--all-kernel options Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 03/29] perf sched timehist: Introduce struct idle_time_data Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 08/29] perf tools: Remove some needless __maybe_unused Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 20/29] samples/bpf: Make perf_event_read() static Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  [PATCH 10/29] perf evsel: Use variable instead of repeating lengthy FD macro Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-20 18:20 +0100
  Re: [GIT PULL 00/29] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2016-12-20 20:20 +0100

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