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Commit 4c69e6ea authored by Sahara's avatar Sahara Committed by Steven Rostedt
Browse files

tracepoints: Prevent null probe from being added 

Somehow tracepoint_entry_add_probe() function allows a null probe function.
And, this may lead to unexpected results since the number of probe
functions in an entry can be counted by checking whether a probe is null
or not in the for-loop.
This patch prevents a null probe from being added.
In tracepoint_entry_remove_probe() function, checking probe parameter
within the for-loop is moved out for code efficiency, leaving the null probe
feature which removes all probe functions in the entry.

Link: http://lkml.kernel.org/r/1365991995-19445-1-git-send-email-kpark3469@gmail.com



Reviewed-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: default avatarSahara <keun-o.park@windriver.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent d2802d07

kernel/tracepoint.c

+13 −8
Original line number Diff line number Diff line
@@ -112,7 +112,8 @@ tracepoint_entry_add_probe(struct tracepoint_entry *entry, 
	int nr_probes = 0;

	struct tracepoint_func *old, *new;



	WARN_ON(!probe);

	if (WARN_ON(!probe))

		return ERR_PTR(-EINVAL);



	debug_print_probes(entry);

	old = entry->funcs;
@@ -152,13 +153,18 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry, 


	debug_print_probes(entry);

	/* (N -> M), (N > 1, M >= 0) probes */

	if (probe) {

		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {

		if (!probe ||

		    (old[nr_probes].func == probe &&

		     old[nr_probes].data == data))

			if (old[nr_probes].func == probe &&

			     old[nr_probes].data == data)

				nr_del++;

		}

	}



	/*

	 * If probe is NULL, then nr_probes = nr_del = 0, and then the

	 * entire entry will be removed.

	 */

	if (nr_probes - nr_del == 0) {

		/* N -> 0, (N > 1) */

		entry->funcs = NULL;
@@ -173,8 +179,7 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry, 
		if (new == NULL)

			return ERR_PTR(-ENOMEM);

		for (i = 0; old[i].func; i++)

			if (probe &&

			    (old[i].func != probe || old[i].data != data))

			if (old[i].func != probe || old[i].data != data)

				new[j++] = old[i];

		new[nr_probes - nr_del].func = NULL;

		entry->refcount = nr_probes - nr_del;