From 42fed7ba44e4e8c1fb27b28ad14490cb1daff3c7 Mon Sep 17 00:00:00 2001 From: Patrice Chotard Date: Thu, 11 Apr 2013 11:01:27 +0200 Subject: pinctrl: move subsystem mutex to pinctrl_dev struct This mutex avoids deadlock in case of use of multiple pin controllers. Before this modification, by using a global mutex, deadlock appeared when, for example, a call to pinctrl_pins_show() locked the pinctrl_mutex, called the ops->pin_dbg_show of a particular pin controller. If this pin controller needs I2C access to retrieve configuration information and I2C driver is using pinctrl to drive its pins, a call to pinctrl_select_state() try to lock again pinctrl_mutex which leads to a deadlock. Notice that the mutex grab from the two direction functions was moved into pinctrl_gpio_direction(). For several cases, we can't replace pinctrl_mutex by pctldev->mutex, because at this stage, pctldev is not accessible : - pinctrl_get()/pinctrl_put() - pinctrl_register_maps() So add respectively pinctrl_list_mutex and pinctrl_maps_mutex in order to protect pinctrl_list and pinctrl_maps list instead. Reintroduce pinctrldev_list_mutex in find_pinctrl_by_of_node(), pinctrl_find_and_add_gpio_range() pinctrl_request_gpio(), pinctrl_free_gpio(), pinctrl_gpio_direction(), pinctrl_devices_show(), pinctrl_register() and pinctrl_unregister() to protect pinctrldev_list. Changes v2->v3: - Fix a missing EXPORT_SYMBOL_GPL() for pinctrl_select_state(). Changes v1->v2: - pinctrl_select_state_locked() is removed, all lock mechanism is located inside pinctrl_select_state(). When parsing the state->setting list, take the per-pin-controller driver lock. (Patrice). - Introduce pinctrldev_list_mutex to protect pinctrldev_list in all functions which parse or modify pictrldev_list. (Patrice). - move find_pinctrl_by_of_node() from pinctrl/devicetree.c to pinctrl/core.c in order to protect pinctrldev_list. (Patrice). - Sink mutex:es into some functions and remove some _locked variants down to where the lists are actually accessed to make things simpler. (Linus) - Drop *all* mutexes completely from pinctrl_lookup_state() and pinctrl_select_state() - no relevant mutex was taken and it was unclear what this was protecting against. (Linus) Reported by : Seraphin Bonnaffe Signed-off-by: Patrice Chotard Signed-off-by: Linus Walleij --- drivers/pinctrl/devicetree.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) (limited to 'drivers/pinctrl/devicetree.c') diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c index c7b7cb477129..340fb4e6c600 100644 --- a/drivers/pinctrl/devicetree.c +++ b/drivers/pinctrl/devicetree.c @@ -95,22 +95,11 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, return pinctrl_register_map(map, num_maps, false, true); } -static struct pinctrl_dev *find_pinctrl_by_of_node(struct device_node *np) -{ - struct pinctrl_dev *pctldev; - - list_for_each_entry(pctldev, &pinctrldev_list, node) - if (pctldev->dev->of_node == np) - return pctldev; - - return NULL; -} - struct pinctrl_dev *of_pinctrl_get(struct device_node *np) { struct pinctrl_dev *pctldev; - pctldev = find_pinctrl_by_of_node(np); + pctldev = get_pinctrl_dev_from_of_node(np); if (!pctldev) return NULL; @@ -138,7 +127,7 @@ static int dt_to_map_one_config(struct pinctrl *p, const char *statename, /* OK let's just assume this will appear later then */ return -EPROBE_DEFER; } - pctldev = find_pinctrl_by_of_node(np_pctldev); + pctldev = get_pinctrl_dev_from_of_node(np_pctldev); if (pctldev) break; /* Do not defer probing of hogs (circular loop) */ -- cgit v1.2.3-59-g8ed1b