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Commit a232e270 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
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tracing/kprobe: Wait for disabling all running kprobe handlers 

Wait for disabling all running kprobe handlers when a kprobe
event is disabled, since the caller, trace_remove_event_call()
supposes that a removing event is disabled completely by
disabling the event.
With this change, ftrace can ensure that there is no running
event handlers after disabling it.

Link: http://lkml.kernel.org/r/20130709093526.20138.93100.stgit@mhiramat-M0-7522



Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent cd92bf61

kernel/trace/trace_kprobe.c

+17 −6
Original line number Diff line number Diff line
@@ -243,11 +243,11 @@ find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file) 
static int

disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)

{

	struct event_file_link *link = NULL;

	int wait = 0;

	int ret = 0;



	if (file) {

		struct event_file_link *link;



		link = find_event_file_link(tp, file);

		if (!link) {

			ret = -EINVAL;
@@ -255,10 +255,7 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file) 
		}



		list_del_rcu(&link->list);

		/* synchronize with kprobe_trace_func/kretprobe_trace_func */

		synchronize_sched();

		kfree(link);



		wait = 1;

		if (!list_empty(&tp->files))

			goto out;
@@ -271,8 +268,22 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file) 
			disable_kretprobe(&tp->rp);

		else

			disable_kprobe(&tp->rp.kp);

		wait = 1;

	}

 out:

	if (wait) {

		/*

		 * Synchronize with kprobe_trace_func/kretprobe_trace_func

		 * to ensure disabled (all running handlers are finished).

		 * This is not only for kfree(), but also the caller,

		 * trace_remove_event_call() supposes it for releasing

		 * event_call related objects, which will be accessed in

		 * the kprobe_trace_func/kretprobe_trace_func.

		 */

		synchronize_sched();

		kfree(link);	/* Ignored if link == NULL */

	}



	return ret;

}