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Commit c877bbd8 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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tools lib traceevent: Add plugin support 

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: default avatarJiri 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.com


Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent a2cb3cf2

tools/lib/traceevent/Makefile

+5 −1
Original line number Diff line number Diff line
@@ -180,7 +180,11 @@ $(obj)/%.o: $(src)/%.c 
%.o: $(src)/%.c

	$(Q)$(call do_compile)



PEVENT_LIB_OBJS = event-parse.o trace-seq.o parse-filter.o parse-utils.o

PEVENT_LIB_OBJS  = event-parse.o

PEVENT_LIB_OBJS += event-plugin.o

PEVENT_LIB_OBJS += trace-seq.o

PEVENT_LIB_OBJS += parse-filter.o

PEVENT_LIB_OBJS += parse-utils.o

PEVENT_LIB_OBJS += kbuffer-parse.o



ALL_OBJS = $(PEVENT_LIB_OBJS)

tools/lib/traceevent/event-parse.h

+5 −0
Original line number Diff line number Diff line
@@ -377,6 +377,11 @@ enum pevent_errno { 
};

#undef _PE



struct plugin_list;



struct plugin_list *traceevent_load_plugins(struct pevent *pevent);

void traceevent_unload_plugins(struct plugin_list *plugin_list);



struct cmdline;

struct cmdline_list;

struct func_map;

tools/lib/traceevent/event-plugin.c

0 → 100644
+202 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2009, 2010 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>

 *

 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation;

 * version 2.1 of the License (not later!)

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not,  see <http://www.gnu.org/licenses>

 *

 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 */



#include <string.h>

#include <dlfcn.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <dirent.h>

#include "event-parse.h"

#include "event-utils.h"



#define LOCAL_PLUGIN_DIR ".traceevent/plugins"



struct plugin_list {

	struct plugin_list	*next;

	char			*name;

	void			*handle;

};



static void

load_plugin(struct pevent *pevent, const char *path,

	    const char *file, void *data)

{

	struct plugin_list **plugin_list = data;

	pevent_plugin_load_func func;

	struct plugin_list *list;

	const char *alias;

	char *plugin;

	void *handle;



	plugin = malloc_or_die(strlen(path) + strlen(file) + 2);



	strcpy(plugin, path);

	strcat(plugin, "/");

	strcat(plugin, file);



	handle = dlopen(plugin, RTLD_NOW | RTLD_GLOBAL);

	if (!handle) {

		warning("could not load plugin '%s'\n%s\n",

			plugin, dlerror());

		goto out_free;

	}



	alias = dlsym(handle, PEVENT_PLUGIN_ALIAS_NAME);

	if (!alias)

		alias = file;



	func = dlsym(handle, PEVENT_PLUGIN_LOADER_NAME);

	if (!func) {

		warning("could not find func '%s' in plugin '%s'\n%s\n",

			PEVENT_PLUGIN_LOADER_NAME, plugin, dlerror());

		goto out_free;

	}



	list = malloc_or_die(sizeof(*list));

	list->next = *plugin_list;

	list->handle = handle;

	list->name = plugin;

	*plugin_list = list;



	pr_stat("registering plugin: %s", plugin);

	func(pevent);

	return;



 out_free:

	free(plugin);

}



static void

load_plugins_dir(struct pevent *pevent, const char *suffix,

		 const char *path,

		 void (*load_plugin)(struct pevent *pevent,

				     const char *path,

				     const char *name,

				     void *data),

		 void *data)

{

	struct dirent *dent;

	struct stat st;

	DIR *dir;

	int ret;



	ret = stat(path, &st);

	if (ret < 0)

		return;



	if (!S_ISDIR(st.st_mode))

		return;



	dir = opendir(path);

	if (!dir)

		return;



	while ((dent = readdir(dir))) {

		const char *name = dent->d_name;



		if (strcmp(name, ".") == 0 ||

		    strcmp(name, "..") == 0)

			continue;



		/* Only load plugins that end in suffix */

		if (strcmp(name + (strlen(name) - strlen(suffix)), suffix) != 0)

			continue;



		load_plugin(pevent, path, name, data);

	}



	closedir(dir);

}



static void

load_plugins(struct pevent *pevent, const char *suffix,

	     void (*load_plugin)(struct pevent *pevent,

				 const char *path,

				 const char *name,

				 void *data),

	     void *data)

{

	char *home;

	char *path;

	char *envdir;



	/*

	 * If a system plugin directory was defined,

	 * check that first.

	 */

#ifdef PLUGIN_DIR

	load_plugins_dir(pevent, suffix, PLUGIN_DIR, load_plugin, data);

#endif



	/*

	 * Next let the environment-set plugin directory

	 * override the system defaults.

	 */

	envdir = getenv("TRACEEVENT_PLUGIN_DIR");

	if (envdir)

		load_plugins_dir(pevent, suffix, envdir, load_plugin, data);



	/*

	 * Now let the home directory override the environment

	 * or system defaults.

	 */

	home = getenv("HOME");

	if (!home)

		return;



	path = malloc_or_die(strlen(home) + strlen(LOCAL_PLUGIN_DIR) + 2);



	strcpy(path, home);

	strcat(path, "/");

	strcat(path, LOCAL_PLUGIN_DIR);



	load_plugins_dir(pevent, suffix, path, load_plugin, data);



	free(path);

}



struct plugin_list*

traceevent_load_plugins(struct pevent *pevent)

{

	struct plugin_list *list = NULL;



	load_plugins(pevent, ".so", load_plugin, &list);

	return list;

}



void

traceevent_unload_plugins(struct plugin_list *plugin_list)

{

	pevent_plugin_unload_func func;

	struct plugin_list *list;



	while (plugin_list) {

		list = plugin_list;

		plugin_list = list->next;

		func = dlsym(list->handle, PEVENT_PLUGIN_UNLOADER_NAME);

		if (func)

			func();

		dlclose(list->handle);

		free(list->name);

		free(list);

	}

}