[RFC][PATCH 00/10] tracing: Add triggers to trace_marker writes

[Steven Rostedt <rostedt@goodmis.org>]

A few people have asked for this in the past, and I finally got around
to implementing it. What this does is to allow writes into trace_marker
to initiate a trigger.

The trace_marker event is described in:

 tracefs/events/ftrace/print

Thus the trigger file is added there:

 tracefs/events/ftrace/print/trigger

As there's already a "hist" file there, everything appears to work
just like any other trigger to an event. See the last patch for
documentation on how to use the triggers to a trace_marker write.

By the way, the patch:

  tracing: Prevent further users of zero size static arrays in trace events

May prevent your kernel from building if you include Xen. You will need
to add this patch to make it work.

 http://lkml.kernel.org/r/20180509144605.5a220327@gandalf.local.home

-- Steve


Steven Rostedt (VMware) (10):
      tracing: Do not reference event data in post call triggers
      tracing: Add __find_event_file() to find event files without restrictions
      tracing: Have event_trace_init() called by trace_init_tracefs()
      tracing: Add brackets in ftrace event dynamic arrays
      tracing: Do not show filter file for ftrace internal events
      tracing: Add trigger file for trace_markers tracefs/ftrace/print
      tracing: Have zero size length in filter logic be full string
      tracing: Prevent further users of zero size static arrays in trace events
      tracing: Allow histogram triggers to access ftrace internal events
      tracing: Document trace_marker triggers

----
 Documentation/trace/events.rst      |   6 +-
 Documentation/trace/ftrace.rst      |   5 +
 Documentation/trace/histogram.txt   | 546 +++++++++++++++++++++++++++++++++++-
 include/linux/trace_events.h        |   3 +-
 include/trace/trace_events.h        |   1 +
 kernel/trace/trace.c                |  19 ++
 kernel/trace/trace.h                |   9 +-
 kernel/trace/trace_entries.h        |   6 +-
 kernel/trace/trace_events.c         |  36 ++-
 kernel/trace/trace_events_filter.c  |  23 +-
 kernel/trace/trace_events_hist.c    |   2 +-
 kernel/trace/trace_events_trigger.c |   6 +-
 kernel/trace/trace_export.c         |   9 +-
 13 files changed, 634 insertions(+), 37 deletions(-)