=============================================
[ INFO: possible recursive locking detected ]
4.2.0-rc6-00013-g5d050ed-dirty #55 Not tainted
---------------------------------------------
sh/63 is trying to acquire lock:
 (class){......}, at: [<c009b91c>] __irq_get_desc_lock+0x50/0x94

but task is already holding lock:
 (class){......}, at: [<c009b91c>] __irq_get_desc_lock+0x50/0x94

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(class);
  lock(class);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

7 locks held by sh/63:
 #0:  (sb_writers#4){.+.+.+}, at: [<c016bbb8>] vfs_write+0x13c/0x164
 #1:  (&of->mutex){+.+.+.}, at: [<c01debf4>] kernfs_fop_write+0x4c/0x1a0
 #2:  (s_active#36){.+.+.+}, at: [<c01debfc>] kernfs_fop_write+0x54/0x1a0
 #3:  (pm_mutex){+.+.+.}, at: [<c009758c>] pm_suspend+0xec/0x4c4
 #4:  (&dev->mutex){......}, at: [<c03f77f8>] __device_suspend+0xd4/0x398
 #5:  (&gpio->lock){+.+.+.}, at: [<c009b940>] __irq_get_desc_lock+0x74/0x94
 #6:  (class){......}, at: [<c009b91c>] __irq_get_desc_lock+0x50/0x94

stack backtrace:
CPU: 0 PID: 63 Comm: sh Not tainted 4.2.0-rc6-00013-g5d050ed-dirty #55
Hardware name: Generic DRA74X (Flattened Device Tree)
[<c0016e24>] (unwind_backtrace) from [<c0013338>] (show_stack+0x10/0x14)
[<c0013338>] (show_stack) from [<c05f6b24>] (dump_stack+0x84/0x9c)
[<c05f6b24>] (dump_stack) from [<c00903f4>] (__lock_acquire+0x19c0/0x1e20)
[<c00903f4>] (__lock_acquire) from [<c0091098>] (lock_acquire+0xa8/0x128)
[<c0091098>] (lock_acquire) from [<c05fd61c>] (_raw_spin_lock_irqsave+0x38/0x4c)
[<c05fd61c>] (_raw_spin_lock_irqsave) from [<c009b91c>] (__irq_get_desc_lock+0x50/0x94)
[<c009b91c>] (__irq_get_desc_lock) from [<c009c4f4>] (irq_set_irq_wake+0x20/0xfc)
[<c009c4f4>] (irq_set_irq_wake) from [<c0393ac4>] (pcf857x_irq_set_wake+0x24/0x54)
[<c0393ac4>] (pcf857x_irq_set_wake) from [<c009c560>] (irq_set_irq_wake+0x8c/0xfc)
[<c009c560>] (irq_set_irq_wake) from [<c04a02ac>] (gpio_keys_suspend+0x70/0xd4)
[<c04a02ac>] (gpio_keys_suspend) from [<c03f6a00>] (dpm_run_callback+0x50/0x124)
[<c03f6a00>] (dpm_run_callback) from [<c03f7830>] (__device_suspend+0x10c/0x398)
[<c03f7830>] (__device_suspend) from [<c03f90f0>] (dpm_suspend+0x134/0x2f4)
[<c03f90f0>] (dpm_suspend) from [<c0096e20>] (suspend_devices_and_enter+0xa8/0x728)
[<c0096e20>] (suspend_devices_and_enter) from [<c00977cc>] (pm_suspend+0x32c/0x4c4)
[<c00977cc>] (pm_suspend) from [<c0096060>] (state_store+0x64/0xb8)
[<c0096060>] (state_store) from [<c01dec64>] (kernfs_fop_write+0xbc/0x1a0)
[<c01dec64>] (kernfs_fop_write) from [<c016b280>] (__vfs_write+0x20/0xd8)
[<c016b280>] (__vfs_write) from [<c016bb0c>] (vfs_write+0x90/0x164)
[<c016bb0c>] (vfs_write) from [<c016c330>] (SyS_write+0x44/0x9c)
[<c016c330>] (SyS_write) from [<c000f500>] (ret_fast_syscall+0x0/0x54)

Lets fix it by using separate lockdep class for each registered GPIO
IRQ Chip. This is done by wrapping gpiochip_irqchip_add call into macros.

The implementation of this patch inspired by solution done by Nicolas
Boichat for regmap [3]

[1] http://www.spinics.net/lists/linux-gpio/msg05844.html
[2] http://www.spinics.net/lists/linux-gpio/msg06021.html
[3] http://www.spinics.net/lists/arm-kernel/msg429834.html

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roger Quadros <rogerq@ti.com>
Reported-by: Roger Quadros <rogerq@ti.com>
Tested-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
Changes in v2:
- removed accidental change in gpio chip structure description.

 drivers/gpio/gpiolib.c      | 27 ++++++++++++++-------------
 include/linux/gpio/driver.h | 26 +++++++++++++++++++++-----
 2 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 34f95fb..b562dd3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -462,12 +462,6 @@ void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
 }
 EXPORT_SYMBOL_GPL(gpiochip_set_chained_irqchip);
 
-/*
- * This lock class tells lockdep that GPIO irqs are in a different
- * category than their parents, so it won't report false recursion.
- */
-static struct lock_class_key gpiochip_irq_lock_class;
-
 /**
  * gpiochip_irq_map() - maps an IRQ into a GPIO irqchip
  * @d: the irqdomain used by this irqchip
@@ -484,7 +478,11 @@ static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
 	struct gpio_chip *chip = d->host_data;
 
 	irq_set_chip_data(irq, chip);
-	irq_set_lockdep_class(irq, &gpiochip_irq_lock_class);
+	/*
+	 * This lock class tells lockdep that GPIO irqs are in a different
+	 * category than their parents, so it won't report false recursion.
+	 */
+	irq_set_lockdep_class(irq, chip->lock_key);
 	irq_set_chip_and_handler(irq, chip->irqchip, chip->irq_handler);
 	/* Chips that can sleep need nested thread handlers */
 	if (chip->can_sleep && !chip->irq_not_threaded)
@@ -589,6 +587,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip)
  * @handler: the irq handler to use (often a predefined irq core function)
  * @type: the default type for IRQs on this irqchip, pass IRQ_TYPE_NONE
  * to have the core avoid setting up any default type in the hardware.
+ * @lock_key: lockdep class
  *
  * This function closely associates a certain irqchip with a certain
  * gpiochip, providing an irq domain to translate the local IRQs to
@@ -604,11 +603,12 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip)
  * the pins on the gpiochip can generate a unique IRQ. Everything else
  * need to be open coded.
  */
-int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
-			 struct irq_chip *irqchip,
-			 unsigned int first_irq,
-			 irq_flow_handler_t handler,
-			 unsigned int type)
+int _gpiochip_irqchip_add(struct gpio_chip *gpiochip,
+			  struct irq_chip *irqchip,
+			  unsigned int first_irq,
+			  irq_flow_handler_t handler,
+			  unsigned int type,
+			  struct lock_class_key *lock_key)
 {
 	struct device_node *of_node;
 	unsigned int offset;
@@ -634,6 +634,7 @@ int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
 	gpiochip->irq_handler = handler;
 	gpiochip->irq_default_type = type;
 	gpiochip->to_irq = gpiochip_to_irq;
+	gpiochip->lock_key = lock_key;
 	gpiochip->irqdomain = irq_domain_add_simple(of_node,
 					gpiochip->ngpio, first_irq,
 					&gpiochip_domain_ops, gpiochip);
@@ -671,7 +672,7 @@ int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(gpiochip_irqchip_add);
+EXPORT_SYMBOL_GPL(_gpiochip_irqchip_add);
 
 #else /* CONFIG_GPIOLIB_IRQCHIP */
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index c8393cd..0c7004d 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -6,6 +6,7 @@
 #include <linux/irq.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
+#include <linux/lockdep.h>
 #include <linux/pinctrl/pinctrl.h>
 
 struct device;
@@ -126,6 +127,7 @@ struct gpio_chip {
 	irq_flow_handler_t	irq_handler;
 	unsigned int		irq_default_type;
 	int			irq_parent;
+	struct lock_class_key	*lock_key;
 #endif
 
 #if defined(CONFIG_OF_GPIO)
@@ -171,11 +173,25 @@ void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
 		int parent_irq,
 		irq_flow_handler_t parent_handler);
 
-int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
-		struct irq_chip *irqchip,
-		unsigned int first_irq,
-		irq_flow_handler_t handler,
-		unsigned int type);
+int _gpiochip_irqchip_add(struct gpio_chip *gpiochip,
+			  struct irq_chip *irqchip,
+			  unsigned int first_irq,
+			  irq_flow_handler_t handler,
+			  unsigned int type,
+			  struct lock_class_key *lock_key);
+
+#ifdef CONFIG_LOCKDEP
+#define gpiochip_irqchip_add(...)				\
+(								\
+	({							\
+		static struct lock_class_key _key;		\
+		_gpiochip_irqchip_add(__VA_ARGS__, &_key);	\
+	})							\
+)
+#else
+#define gpiochip_irqchip_add(...)				\
+	_gpiochip_irqchip_add(__VA_ARGS__, NULL)
+#endif
 
 #endif /* CONFIG_GPIOLIB_IRQCHIP */
 
