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Commit 87107a25 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing/kprobes: Simplify the logic of enable_trace_kprobe() 

The function enable_trace_kprobe() performs slightly differently if the file
parameter is passed in as NULL on non-NULL. Instead of checking file twice,
move the code between the two tests into a static inline helper function to
make the code easier to follow.

Link: http://lkml.kernel.org/r/20180725224728.7b1d5db2@vmware.local.home
Link: http://lkml.kernel.org/r/20180726121152.4dd54330@gandalf.local.home



Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 72809cbf

kernel/trace/trace_kprobe.c

+24 −18
Original line number Diff line number Diff line
@@ -393,6 +393,20 @@ static struct trace_kprobe *find_trace_kprobe(const char *event, 
	return NULL;

}



static inline int __enable_trace_kprobe(struct trace_kprobe *tk)

{

	int ret = 0;



	if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {

		if (trace_kprobe_is_return(tk))

			ret = enable_kretprobe(&tk->rp);

		else

			ret = enable_kprobe(&tk->rp.kp);

	}



	return ret;

}



/*

 * Enable trace_probe

 * if the file is NULL, enable "perf" handler, or enable "trace" handler.
@@ -400,7 +414,7 @@ static struct trace_kprobe *find_trace_kprobe(const char *event, 
static int

enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)

{

	struct event_file_link *link = NULL;

	struct event_file_link *link;

	int ret = 0;



	if (file) {
@@ -414,27 +428,19 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) 
		list_add_tail_rcu(&link->list, &tk->tp.files);



		tk->tp.flags |= TP_FLAG_TRACE;

	} else

		tk->tp.flags |= TP_FLAG_PROFILE;



	if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {

		if (trace_kprobe_is_return(tk))

			ret = enable_kretprobe(&tk->rp);

		else

			ret = enable_kprobe(&tk->rp.kp);

	}



		ret = __enable_trace_kprobe(tk);

		if (ret) {

		if (file) {

			/* Notice the if is true on not WARN() */

			if (!WARN_ON_ONCE(!link))

			list_del_rcu(&link->list);

			kfree(link);

			tk->tp.flags &= ~TP_FLAG_TRACE;

		}



	} else {

		tk->tp.flags |= TP_FLAG_PROFILE;

		ret = __enable_trace_kprobe(tk);

		if (ret)

			tk->tp.flags &= ~TP_FLAG_PROFILE;

	}

	}

 out:

	return ret;

}