pinctrl: core: Add proper mutex lock in pinctrl_request_gpio

This one is missed in commit 42fed7ba "pinctrl: move subsystem mutex to
pinctrl_dev struct".

I think this fixes the race between pin_free() and pin_request() calls.
It protects accessing the members of pctldev->desc.
(e.g. update desc->mux_usecount, desc->gpio_owner, desc->mux_owner, etc)
Current code grabs pctldev->mutex before calling pinmux_free_gpio(),
but did not grab the mutex while calling pinmux_request_gpio().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 7094a81..054d14b 100644 (file)
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -562,11 +562,15 @@ int pinctrl_request_gpio(unsigned gpio)
                return ret;
        }
 
+       mutex_lock(&pctldev->mutex);
+
        /* Convert to the pin controllers number space */
        pin = gpio_to_pin(range, gpio);
 
        ret = pinmux_request_gpio(pctldev, range, pin, gpio);
 
+       mutex_unlock(&pctldev->mutex);
+
        return ret;
 }
 EXPORT_SYMBOL_GPL(pinctrl_request_gpio);