perf tools: Fix a bug of segmentation fault

Fix the 'segmentation fault' bug of 'perf list --list-cmds', which also
happens in other cases (e.g. record, report ...). This bug happens when
there are no cmds to list at all.

Example:

Before this patch:

  $ perf list --list-cmds
  Segmentation fault
  $

  After this patch:
  $ perf list --list-cmds
  $

As shown above, the result prints nothing rather than a segmentation
fault. The null result means 'perf list' has no cmds to display at this
time.

Signed-off-by: Yunlong Song <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions