v3.18.129-rt111 rt-stable review patch. If anyone has any objections,
please let me know.
------------------
From: Lukas Wunner <lukas@xxxxxxxxx>
[Upstream rt-devel commit 55016fa934eb0d4e037beef2b2f503012dfebeac]
[Upstream commit 71dfaa749f2f7c1722ebf6716d3f797a04528cba]
The BCM2835 pinctrl driver acquires a spinlock in its ->irq_enable,
->irq_disable and ->irq_set_type callbacks. Spinlocks become sleeping
locks with CONFIG_PREEMPT_RT_FULL=y, therefore invocation of one of the
callbacks in atomic context may cause a hard lockup if at least two GPIO
pins in the same bank are used as interrupts. The issue doesn't occur
with just a single interrupt pin per bank because the lock is never
contended. I'm experiencing such lockups with GPIO 8 and 28 used as
level-triggered interrupts, i.e. with ->irq_disable being invoked on
reception of every IRQ.
The critical section protected by the spinlock is very small (one bitop
and one RMW of an MMIO register), hence converting to a raw spinlock
seems a better trade-off than converting the driver to threaded IRQ
handling (which would increase latency to handle an interrupt).
Cc: Mathias Duckeck <m.duckeck@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Acked-by: Julia Cartwright <julia@xxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Conflicts:
drivers/pinctrl/bcm/pinctrl-bcm2835.c
---
drivers/pinctrl/pinctrl-bcm2835.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/pinctrl/pinctrl-bcm2835.c b/drivers/pinctrl/pinctrl-bcm2835.c
index eabba02f71f9..9a975a12b8e3 100644
--- a/drivers/pinctrl/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/pinctrl-bcm2835.c
@@ -106,7 +106,7 @@ struct bcm2835_pinctrl {
struct pinctrl_gpio_range gpio_range;
struct bcm2835_gpio_irqdata irq_data[BCM2835_NUM_BANKS];
- spinlock_t irq_lock[BCM2835_NUM_BANKS];
+ raw_spinlock_t irq_lock[BCM2835_NUM_BANKS];
};
static struct lock_class_key gpio_lock_class;
@@ -465,10 +465,10 @@ static void bcm2835_gpio_irq_enable(struct irq_data *data)
unsigned bank = GPIO_REG_OFFSET(gpio);
unsigned long flags;
- spin_lock_irqsave(&pc->irq_lock[bank], flags);
+ raw_spin_lock_irqsave(&pc->irq_lock[bank], flags);
set_bit(offset, &pc->enabled_irq_map[bank]);
bcm2835_gpio_irq_config(pc, gpio, true);
- spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
+ raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
}
static void bcm2835_gpio_irq_disable(struct irq_data *data)
@@ -479,10 +479,10 @@ static void bcm2835_gpio_irq_disable(struct irq_data *data)
unsigned bank = GPIO_REG_OFFSET(gpio);
unsigned long flags;
- spin_lock_irqsave(&pc->irq_lock[bank], flags);
+ raw_spin_lock_irqsave(&pc->irq_lock[bank], flags);
bcm2835_gpio_irq_config(pc, gpio, false);
clear_bit(offset, &pc->enabled_irq_map[bank]);
- spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
+ raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
}
static int __bcm2835_gpio_irq_set_type_disabled(struct bcm2835_pinctrl *pc,
@@ -584,14 +584,14 @@ static int bcm2835_gpio_irq_set_type(struct irq_data *data, unsigned int type)
unsigned long flags;
int ret;
- spin_lock_irqsave(&pc->irq_lock[bank], flags);
+ raw_spin_lock_irqsave(&pc->irq_lock[bank], flags);
if (test_bit(offset, &pc->enabled_irq_map[bank]))
ret = __bcm2835_gpio_irq_set_type_enabled(pc, gpio, type);
else
ret = __bcm2835_gpio_irq_set_type_disabled(pc, gpio, type);
- spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
+ raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags);
return ret;
}
@@ -1004,7 +1004,7 @@ static int bcm2835_pinctrl_probe(struct platform_device *pdev)
pc->irq[i] = irq_of_parse_and_map(np, i);
pc->irq_data[i].pc = pc;
pc->irq_data[i].bank = i;
- spin_lock_init(&pc->irq_lock[i]);
+ raw_spin_lock_init(&pc->irq_lock[i]);
len = strlen(dev_name(pc->dev)) + 16;
name = devm_kzalloc(pc->dev, len, GFP_KERNEL);
--
2.14.1
