Showing better error message in case we fail to open counters due to the
EBUSY error. If we detect oprofile daemon process running, we now
display following message for EBUSY error:

  $ perf record ls
  Error:
  The PMU counters are busy/taken by another profiler.
  We found oprofile daemon running, please stop it and try again.

In case oprofiled was not detected the current error message stays:

  $ perf record ls
  Error:
  The sys_perf_event_open() syscall returned with 16 (Device or resource busy) for event (cycles).
  /bin/dmesg may provide additional information.
  No CONFIG_PERF_EVENTS=y kernel support configured?

Also changing PERF_FLAG_FD_CLOEXEC detection code not to display error
in case of EBUSY error, as it currently does:

  $ perf record ls
  Error:
  perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error 16 (Device or resource busy)
  perf_event_open(..., 0) failed unexpectedly with error 16 (Device or resource busy)
  The PMU counters are busy/taken by another profiler.
  We found oprofile daemon running, please stop it and try again.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Link: http://lkml.kernel.org/r/1406908014-8312-1-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>