Re: [PATCH v2 05/15] tools lib traceevent: Introduced new traceevent API, for adding new plugins directories.

[Namhyung Kim]

On Fri, Jul 3, 2020 at 3:57 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx>
>
> Implement new traceevent plugin API, which can be used to add new plugins
> directories:
> enum tep_plugin_load_priority {
>         TEP_PLUGIN_FIRST,
>         TEP_PLUGIN_LAST,
> };
> int tep_add_plugin_path(struct tep_handle *tep, char *path,
>                         enum tep_plugin_load_priority prio);
>
> It adds the "path" as new plugin directory, in the context of
> the handler "tep". The tep_load_plugins() API searches for plugins
> in this new location. Depending of the priority "prio", the plugins
> from this directory are loaded before (TEP_PLUGIN_FIRST) or after
> (TEP_PLUGIN_LAST) the ordinary libtraceevent plugin locations.
>
> Link: http://lore.kernel.org/linux-trace-devel/20191007114947.17104-2-tz.stoyanov@xxxxxxxxx
> Link: http://lore.kernel.org/linux-trace-devel/20200625100516.365338-6-tz.stoyanov@xxxxxxxxx
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
>  tools/lib/traceevent/event-parse-local.h |  5 +-
>  tools/lib/traceevent/event-parse.c       |  1 +
>  tools/lib/traceevent/event-parse.h       |  7 +++
>  tools/lib/traceevent/event-plugin.c      | 70 ++++++++++++++++++++++++
>  4 files changed, 82 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/traceevent/event-parse-local.h b/tools/lib/traceevent/event-parse-local.h
> index cee469803a34..96a0b0ca0675 100644
> --- a/tools/lib/traceevent/event-parse-local.h
> +++ b/tools/lib/traceevent/event-parse-local.h
> @@ -13,6 +13,7 @@ struct func_map;
>  struct func_list;
>  struct event_handler;
>  struct func_resolver;
> +struct tep_plugins_dir;
>
>  struct tep_handle {
>         int ref_count;
> @@ -47,7 +48,6 @@ struct tep_handle {
>         struct printk_list *printklist;
>         unsigned int printk_count;
>
> -
>         struct tep_event **events;
>         int nr_events;
>         struct tep_event **sort_events;
> @@ -81,10 +81,13 @@ struct tep_handle {
>
>         /* cache */
>         struct tep_event *last_event;
> +
> +       struct tep_plugins_dir *plugins_dir;
>  };
>
>  void tep_free_event(struct tep_event *event);
>  void tep_free_format_field(struct tep_format_field *field);
> +void tep_free_plugin_paths(struct tep_handle *tep);
>
>  unsigned short tep_data2host2(struct tep_handle *tep, unsigned short data);
>  unsigned int tep_data2host4(struct tep_handle *tep, unsigned int data);
> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
> index e1bd2a93c6db..064c100d2d5a 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -7065,6 +7065,7 @@ void tep_free(struct tep_handle *tep)
>         free(tep->events);
>         free(tep->sort_events);
>         free(tep->func_resolver);
> +       tep_free_plugin_paths(tep);
>
>         free(tep);
>  }
> diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
> index 02c0438527de..91f462f5a606 100644
> --- a/tools/lib/traceevent/event-parse.h
> +++ b/tools/lib/traceevent/event-parse.h
> @@ -393,6 +393,13 @@ struct tep_plugin_list;
>
>  #define INVALID_PLUGIN_LIST_OPTION     ((char **)((unsigned long)-1))
>
> +enum tep_plugin_load_priority {
> +       TEP_PLUGIN_FIRST,
> +       TEP_PLUGIN_LAST,
> +};
> +
> +int tep_add_plugin_path(struct tep_handle *tep, char *path,
> +                       enum tep_plugin_load_priority prio);
>  struct tep_plugin_list *tep_load_plugins(struct tep_handle *tep);
>  void tep_unload_plugins(struct tep_plugin_list *plugin_list,
>                         struct tep_handle *tep);
> diff --git a/tools/lib/traceevent/event-plugin.c b/tools/lib/traceevent/event-plugin.c
> index e8f4329ba8e0..1d4f1809cf17 100644
> --- a/tools/lib/traceevent/event-plugin.c
> +++ b/tools/lib/traceevent/event-plugin.c
> @@ -39,6 +39,12 @@ struct tep_plugin_list {
>         void                    *handle;
>  };
>
> +struct tep_plugins_dir {
> +       struct tep_plugins_dir          *next;
> +       char                            *path;
> +       enum tep_plugin_load_priority   prio;
> +};
> +
>  static void lower_case(char *str)
>  {
>         if (!str)
> @@ -544,6 +550,7 @@ void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
>                                                void *data),
>                            void *data)
>  {
> +       struct tep_plugins_dir *dir = NULL;
>         char *home;
>         char *path;
>         char *envdir;
> @@ -552,6 +559,15 @@ void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
>         if (tep && tep->flags & TEP_DISABLE_PLUGINS)
>                 return;
>
> +       if (tep)
> +               dir = tep->plugins_dir;
> +       while (dir) {
> +               if (dir->prio == TEP_PLUGIN_FIRST)
> +                       load_plugins_dir(tep, suffix, dir->path,
> +                                        load_plugin, data);
> +               dir = dir->next;
> +       }
> +
>         /*
>          * If a system plugin directory was defined,
>          * check that first.
> @@ -586,6 +602,15 @@ void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
>
>         load_plugins_dir(tep, suffix, path, load_plugin, data);
>
> +       if (tep)
> +               dir = tep->plugins_dir;
> +       while (dir) {
> +               if (dir->prio == TEP_PLUGIN_LAST)
> +                       load_plugins_dir(tep, suffix, dir->path,
> +                                        load_plugin, data);
> +               dir = dir->next;
> +       }
> +
>         free(path);
>  }
>
> @@ -598,6 +623,51 @@ tep_load_plugins(struct tep_handle *tep)
>         return list;
>  }
>
> +/**
> + * tep_add_plugin_path - Add a new plugin directory.
> + * @tep: Trace event handler.
> + * @path: Path to a directory. All files with extension .so in that

Is the extension (".so") fixed?  I think a new API has the suffix argument
which may change it... ?


> + *       directory will be loaded as plugins.
> + *@prio: Load priority of the plugins in that directory.
> + *
> + * Returns -1 in case of an error, 0 otherwise.
> + */
> +int tep_add_plugin_path(struct tep_handle *tep, char *path,
> +                       enum tep_plugin_load_priority prio)
> +{
> +       struct tep_plugins_dir *dir;
> +
> +       if (!tep || !path)
> +               return -1;
> +
> +       dir = calloc(1, sizeof(*dir));
> +       if (!dir)
> +               return -1;
> +
> +       dir->path = strdup(path);

It needs to check the return value..

Thanks
Namhyung


> +       dir->prio = prio;
> +       dir->next = tep->plugins_dir;
> +       tep->plugins_dir = dir;
> +
> +       return 0;
> +}
> +
> +void tep_free_plugin_paths(struct tep_handle *tep)
> +{
> +       struct tep_plugins_dir *dir;
> +
> +       if (!tep)
> +               return;
> +
> +       dir = tep->plugins_dir;
> +       while (dir) {
> +               tep->plugins_dir = tep->plugins_dir->next;
> +               free(dir->path);
> +               free(dir);
> +               dir = tep->plugins_dir;
> +       }
> +}
> +
>  void
>  tep_unload_plugins(struct tep_plugin_list *plugin_list, struct tep_handle *tep)
>  {
> --
> 2.26.2
>
>