It's not possible to run a package event and a per cpu event in the same
group. This is used by some of the power metrics.  They work correctly
when not using a group.

Normally weak groups should handle that, but in this case EBADF is
returned instead of the normal EINVAL.

  $ strace -e perf_event_open ./perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
  Using CPUID GenuineIntel-6-3E
  perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = -1 EINVAL (Invalid argument)
  perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
  perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
  perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
  perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = 3
  perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, 3, 0) = 4
  perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 1, 0, 0) = -1 EBADF (Bad file descriptor)

and perf errors out.

Make weak groups trigger a fall back for EBADF too. Then this case works correctly:

  $ perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
  Using CPUID GenuineIntel-6-3E
  Weak group for cstate_pkg/c2-residency//2 failed
  cstate_pkg/c2-residency/: 476709882 1000598460 1000598460
  msr/tsc/: 39625837911 12007369110 12007369110

   Performance counter stats for 'system wide':

         476,709,882      cstate_pkg/c2-residency/
      39,625,837,911      msr/tsc/

         1.000697588 seconds time elapsed

  This fixes perf stat -M Power ...

  $ perf stat -M Power --metric-only -a sleep 1

   Performance counter stats for 'system wide':

  Turbo_Utilization  C3_Core_Residency  C6_Core_Residency C7_Core_Residency  C2_Pkg_Residency   C3_Pkg_Residency  C6_Pkg_Residency  C7_Pkg_Residency
       1.0                 0.7                30.0               0.0               0.9                 0.1               0.4                 0.0

         1.001240740 seconds time elapsed
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170905211324.32427-1-andi@firstfloor.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>