tools lib api fs: Store tracing mountpoint for better error message

Storing the actual tracing path mountpoint to display correct
error message hint ('Hint:' line). The error hint rediscovers
mountpoints, but it could be different from what we actually
used in tracing path.

Before we'd display debugfs mount even though tracefs was used:
  $ perf record -e sched:sched_krava ls
  event syntax error: 'sched:sched_krava'
                       \___ can't access trace events

  Error:  No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
  Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
  ...

After this change, correct mountpoint is displayed:
  $ perf record -e sched:sched_krava ls
  event syntax error: 'sched:sched_krava'
                       \___ can't access trace events

  Error:  No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
  Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
  ...

Signed-off-by: Jiri Olsa <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Raphael Beamonte <[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