The traceevent plugins allows developers to have their events print out
information that is more advanced than what can be achieved by the
trace event format files.

As these plugins are used on the userspace side of the tracing tools, it
is only logical that the tools should be able to produce different types
of output for the events. The types of events still need to be defined by
the plugins thus we need a way to pass information from the tool to the
plugin to specify what type of information to be shown.

Not only does the information need to be passed by the tool to plugin, but
the plugin also requires a way to notify the tool of what options it can
provide.

This builds the plugin option infrastructure that is taken from trace-cmd
that is used to allow plugins to produce different output based on the
options specified by the tool.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20140603184154.0a4c031c@gandalf.local.homeSigned-off-by: NJiri Olsa <jolsa@kernel.org>

Add a flag to pevent that will let the callers be able to set it and
keep the system, and perhaps even normal plugins from being loaded.

This is useful when plugins might hide certain information and seeing
the raw events shows what may be going on.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20140603032223.678098063@goodmis.orgSigned-off-by: NJiri Olsa <jolsa@kernel.org>

The PEVENT_PLUGIN_UNLOADER function might need some cleanup using pevent
like unregister some handlers.  So pass pevent as argument.
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Reviewed-by: NJiri Olsa <jolsa@redhat.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1389750340-15965-6-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Removing malloc_or_die calls from event-plugin.c,
replacing them with standard malloc and error path.
Suggested-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1386076182-14484-23-git-send-email-jolsa@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Backporting plugin support for traceevent lib.

Backported from Steven Rostedt's trace-cmd repo (HEAD 0f2c2fb):
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git

It's now possible to use following interface to load plugins
(shared objects) to enhance pevent object functionality.

The plugin interface/hooks are as follows:
(taken from event-parse.h comments)

- 'pevent_plugin_loader' (required)
    The function name to initialized the plugin.

    int pevent_plugin_loader(struct pevent *pevent)

- 'pevent_plugin_unloader' (optional)
    The function called just before unloading

    int pevent_plugin_unloader(void)

- 'pevent_plugin_options'  (optional)
    Plugin options that can be set before loading

    struct plugin_option pevent_plugin_options[] = {
       {
               .name = "option-name",
               .plugin_alias = "overide-file-name", (optional)
               .description = "description of option to show users",
       },
       {
               .name = NULL,
       },
    };

    Array must end with .name = NULL;

    The plugin_alias (below) can be used to give a shorter
    name to access the variable. Useful if a plugin handles
    more than one event.

    NOTE options support is not backported yet.

- 'pevent_plugin_alias' (optional)
    The name to use for finding options (uses filename if not defined)

New traceevent functions are added to search and load
available plugins:

  struct plugin_list*
  traceevent_load_plugins(struct pevent *pevent)
    - loads plusing for 'struct pevent' object and returns
      loaded plugins list

  void traceevent_unload_plugins(struct plugin_list *plugin_list);
    - unload plugin list
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1386076182-14484-3-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>