[PATCH 1/2] pinctrl: st: avoid multiple mutex lock

From: Patrice CHOTARD
Date: Tue Dec 09 2014 - 03:35:33 EST

From: Francesco VIRLINZI <francesco.virlinzi@xxxxxx>

Using the sysfs inteface to inspect the pins configuration
the system can walk around a path which acquires the same
mutex twice.

On STiH407 platform, for example :
cat /sys/kernel/debug/pinctrl/920f080.pin-controller-front0/pinconf-pins
hangs the kernel and never returns.

With this patch the mutex is temporary freed.

Signed-off-by: Francesco Virlinzi <francesco.virlinzi@xxxxxx>
Signed-off-by: Patrice Chotard <patrice.chotard@xxxxxx>
drivers/pinctrl/pinctrl-st.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index caeeb1c..2870a68 100644
--- a/drivers/pinctrl/pinctrl-st.c
+++ b/drivers/pinctrl/pinctrl-st.c
@@ -1012,8 +1012,10 @@ static void st_pinconf_dbg_show(struct pinctrl_dev *pctldev,
struct seq_file *s, unsigned pin_id)
unsigned long config;
- st_pinconf_get(pctldev, pin_id, &config);

+ mutex_unlock(&pctldev->mutex);
+ st_pinconf_get(pctldev, pin_id, &config);
+ mutex_lock(&pctldev->mutex);
seq_printf(s, "[OE:%ld,PU:%ld,OD:%ld]\n"

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