pinctrl: protect pinctrl_list add

We have few fedora bug reports about list corruption on pinctrl,
for example:
https://bugzilla.redhat.com/show_bug.cgi?id=1051918

Most likely corruption happen due lack of protection of pinctrl_list
when adding new nodes to it. Patch corrects that.

Fixes: 42fed7b ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Cc: [email protected]
Signed-off-by: Stanislaw Gruszka <[email protected]>
Acked-by: Stephen Warren <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>

Author: Stanislaw Gruszka

drivers/pinctrl/core.c

@@ -851,7 +851,9 @@ static struct pinctrl *create_pinctrl(struct device *dev)
 	kref_init(&p->users);
 
 	/* Add the pinctrl handle to the global list */
+	mutex_lock(&pinctrl_list_mutex);
 	list_add_tail(&p->node, &pinctrl_list);
+	mutex_unlock(&pinctrl_list_mutex);
 
 	return p;
 }