Commit 9dc7dc75 authored by Tzvetomir Stoyanov (VMware)'s avatar Tzvetomir Stoyanov (VMware) Committed by Arnaldo Carvalho de Melo
Browse files

libtraceevent: Document tep_load_plugins_hook() 

Add description of tep_load_plugins_hook() traceevent API. Updated
library man pages with description of the tep_load_plugins_hook() API.

Link: https://lore.kernel.org/r/CAM9d7cgLBWCrEHwz+Lhv5x5EXGcNWB0QQoeGh3OKh2JfR=dV9Q@mail.gmail.com
Link: https://lore.kernel.org/linux-trace-devel/20200714103027.2477584-2-tz.stoyanov@gmail.com
Link: https://lore.kernel.org/linux-trace-devel/20200716092014.2613403-2-tz.stoyanov@gmail.com



Suggested-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarTzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200722011754.720060785@goodmis.org


Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 4b0297ef

tools/lib/traceevent/Documentation/libtraceevent-plugins.txt

+24 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ libtraceevent(3) 


NAME

----

tep_load_plugins, tep_unload_plugins - Load / unload traceevent plugins.

tep_load_plugins, tep_unload_plugins, tep_load_plugins_hook - Load / unload traceevent plugins.



SYNOPSIS

--------
@@ -13,6 +13,12 @@ SYNOPSIS 


struct tep_plugin_list pass:[*]*tep_load_plugins*(struct tep_handle pass:[*]_tep_);

void *tep_unload_plugins*(struct tep_plugin_list pass:[*]_plugin_list_, struct tep_handle pass:[*]_tep_);

void *tep_load_plugins_hook*(struct tep_handle pass:[*]_tep_, const char pass:[*]_suffix_,

			   void (pass:[*]_load_plugin_)(struct tep_handle pass:[*]tep,

					       const char pass:[*]path,

					       const char pass:[*]name,

					       void pass:[*]data),

			   void pass:[*]_data_);

--



DESCRIPTION
@@ -22,11 +28,13 @@ directories. The _tep_ argument is trace event parser context. 
The plugin directories are :

[verse]

--

	- Directories, specified in _tep_->plugins_dir with priority TEP_PLUGIN_FIRST

	- System's plugin directory, defined at the library compile time. It

	  depends on the library installation prefix and usually is

	  _(install_preffix)/lib/traceevent/plugins_

	- Directory, defined by the environment variable _TRACEEVENT_PLUGIN_DIR_

	- User's plugin directory, located at _~/.local/lib/traceevent/plugins_

	- Directories, specified in _tep_->plugins_dir with priority TEP_PLUGIN_LAST

--

Loading of plugins can be controlled by the _tep_flags_, using the

_tep_set_flag()_ API:
@@ -44,6 +52,12 @@ _tep_load_plugins()_. The _tep_ argument is trace event parser context. The 
_plugin_list_ is the list of loaded plugins, returned by

the _tep_load_plugins()_ function.



The _tep_load_plugins_hook_ function walks through all directories with plugins

and calls user specified _load_plugin()_ hook for each plugin file. Only files

with given _suffix_ are considered to be plugins. The _data_ is a user specified

context, passed to _load_plugin()_. Directories and the walk order are the same

as in _tep_load_plugins()_ API.



RETURN VALUE

------------

The _tep_load_plugins()_ function returns a list of successfully loaded plugins,
@@ -63,6 +77,15 @@ if (plugins == NULL) { 
}

...

tep_unload_plugins(plugins, tep);

...

void print_plugin(struct tep_handle *tep, const char *path,

		  const char *name, void *data)

{

	pritnf("Found libtraceevent plugin %s/%s\n", path, name);

}

...

tep_load_plugins_hook(tep, ".so", print_plugin, NULL);

...

--



FILES

tools/lib/traceevent/event-plugin.c

+16 −0
Original line number Diff line number Diff line
@@ -543,6 +543,22 @@ load_plugins_dir(struct tep_handle *tep, const char *suffix, 
	closedir(dir);

}



/**

 * tep_load_plugins_hook - call a user specified callback to load a plugin

 * @tep: handler to traceevent context

 * @suffix: filter only plugin files with given suffix

 * @load_plugin: user specified callback, called for each plugin file

 * @data: custom context, passed to @load_plugin

 *

 * Searches for traceevent plugin files and calls @load_plugin for each

 * The order of plugins search is:

 *  - Directories, specified in @tep->plugins_dir and priority TEP_PLUGIN_FIRST

 *  - Directory, specified at compile time with PLUGIN_TRACEEVENT_DIR

 *  - Directory, specified by environment variable TRACEEVENT_PLUGIN_DIR

 *  - In user's home: ~/.local/lib/traceevent/plugins/

 *  - Directories, specified in @tep->plugins_dir and priority TEP_PLUGIN_LAST

 *

 */

void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,

			   void (*load_plugin)(struct tep_handle *tep,

					       const char *path,