[PATCH v2] pinctrl: protect pinctrl_list add

[Stanislaw Gruszka <sgruszka@redhat.com>]

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: 42fed7ba44e ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
I only compile tested patch, also did not get test results from bug
reporters yet. But I'm pretty confident that patch fixes the problem
and does not cause any other deadlock.

v1 -> v2: point correct first bad commit.

 drivers/pinctrl/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 5ee61a4..cab020a 100644
--- a/drivers/pinctrl/core.c
+++ b/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;
 }
-- 
1.7.11.7