If a driver calls enable_irq_wake() on a gpio turned interrupt
from the msm pinctrl driver we'll get a lockdep warning like so:
=============================================
[ INFO: possible recursive locking detected ]
3.14.0-rc3 #2 Not tainted
---------------------------------------------
modprobe/52 is trying to acquire lock:
(&irq_desc_lock_class){-.....}, at: [<c026aea0>] __irq_get_desc_lock+0x48/0x88
but task is already holding lock:
(&irq_desc_lock_class){-.....}, at: [<c026aea0>] __irq_get_desc_lock+0x48/0x88
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&irq_desc_lock_class);
lock(&irq_desc_lock_class);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by modprobe/52:
#0: (&__lockdep_no_validate__){......}, at: [<c04f2864>] __driver_attach+0x48/0x98
#1: (&__lockdep_no_validate__){......}, at: [<c04f2874>] __driver_attach+0x58/0x98
#2: (&irq_desc_lock_class){-.....}, at: [<c026aea0>] __irq_get_desc_lock+0x48/0x88
#3: (&(&pctrl->lock)->rlock){......}, at: [<c04bb4b8>] msm_gpio_irq_set_wake+0x20/0xa8
Silence it by putting the gpios into their own lock class.
Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
---
drivers/pinctrl/pinctrl-msm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/pinctrl/pinctrl-msm.c b/drivers/pinctrl/pinctrl-msm.c
index ef2bf3126da6..ac7223dab4a3 100644
--- a/drivers/pinctrl/pinctrl-msm.c
+++ b/drivers/pinctrl/pinctrl-msm.c
@@ -869,6 +869,12 @@ static void msm_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
chained_irq_exit(chip, desc);
}
+/*
+ * 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 gpio_lock_class;
+
static int msm_gpio_init(struct msm_pinctrl *pctrl)
{
struct gpio_chip *chip;
@@ -907,6 +913,7 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
for (i = 0; i < chip->ngpio; i++) {
irq = irq_create_mapping(pctrl->domain, i);
+ irq_set_lockdep_class(irq, &gpio_lock_class);
irq_set_chip_and_handler(irq, &msm_gpio_irq_chip, handle_edge_irq);
irq_set_chip_data(irq, pctrl);
}
--
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