linux-kernel - Re: [PATCH 06/17] tools lib traceevent: Add pevent_unregister_event

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Message-ID: <20140115111839.73d85422@gandalf.local.home>
Date:	Wed, 15 Jan 2014 11:18:39 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 06/17] tools lib traceevent: Add
 pevent_unregister_event_handler()

On Wed, 15 Jan 2014 10:45:29 +0900
Namhyung Kim <namhyung@...nel.org> wrote:
  
>  	pr_stat("overriding event (%d) %s:%s with new print handler",
>  		event->id, event->system, event->name);
> @@ -5637,6 +5649,79 @@ int pevent_register_event_handler(struct pevent *pevent, int id,
>  	return -1;
>  }
>  
> +static int handle_matches(struct event_handler *handler, int id,
> +			  const char *sys_name, const char *event_name,
> +			  pevent_event_handler_func func, void *context)
> +{
> +	if (id >= 0 && id != handler->id)
> +		return 0;
> +
> +	if (event_name && (strcmp(event_name, handler->event_name) != 0))
> +		return 0;
> +
> +	if (sys_name && (strcmp(sys_name, handler->sys_name) != 0))
> +		return 0;
> +
> +	if (func != handler->func || context != handler->context)
> +		return 0;
> +
> +	return 1;
> +}
> +
> +/**
> + * pevent_unregister_event_handler - unregister an existing event handler
> + * @pevent: the handle to the pevent
> + * @id: the id of the event to unregister
> + * @sys_name: the system name the handler belongs to
> + * @event_name: the name of the event handler
> + * @func: the function to call to parse the event information
> + * @context: the data to be passed to @func
> + *
> + * This function removes existing event handler (parser).
> + *
> + * If @id is >= 0, then it is used to find the event.
> + * else @sys_name and @event_name are used.
> + *
> + * Returns 0 if handler was removed successfully, -1 if event was not found.
> + */
> +int pevent_unregister_event_handler(struct pevent *pevent, int id,
> +				    const char *sys_name, const char *event_name,
> +				    pevent_event_handler_func func, void *context)
> +{
> +	struct event_format *event;
> +	struct event_handler *handle;
> +	struct event_handler **next;
> +
> +	event = pevent_search_event(pevent, id, sys_name, event_name);
> +	if (event == NULL)
> +		goto not_found;
> +
> +	if (event->handler == func && event->context == context) {
> +		pr_stat("overriding event (%d) %s:%s with default print handler",

Should we use the word "overriding" again? Perhaps saying:

"removing override print handler (%d) %s:%s. Going back to default handler."

Or something?

-- Steve

> +			event->id, event->system, event->name);
> +
> +		event->handler = NULL;
> +		event->context = NULL;
> +		return 0;
> +	}
> +
> +not_found:
> +	for (next = &pevent->handlers; *next; next = &(*next)->next) {
> +		handle = *next;
> +		if (handle_matches(handle, id, sys_name, event_name,
> +				   func, context))
> +			break;
> +	}
> +
> +	if (!(*next))
> +		return -1;
> +
> +	*next = handle->next;
> +	free_handler(handle);
> +
> +	return 0;
> +}
> +
--
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