[PATCH 1/4] gpio: mt7621: avoid corruption of shared interrupt trigger state

[Sergio Paracuellos <sergio.paracuellos@gmail.com>]

The bank-shared fields like 'rising' and 'falling' are modified using
non-atomic read-modify-write operations. Since every gpio chip instance
represents an entire bank of 32 pins, if 'mediatek_gpio_irq_type()' is
called concurrently for different IRQs on the same bank a possible overwrite
of each other's configuration is possible. Thus, protect this state with
'gpio_generic_lock_irqsave' lock in the same way it is handled in irp_chip
'mediatek_gpio_irq_mask()' and 'mediatek_gpio_irq_unmask()' callbacks.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
---
 drivers/gpio/gpio-mt7621.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-mt7621.c b/drivers/gpio/gpio-mt7621.c
index a814885ccd5d..ceb99641baee 100644
--- a/drivers/gpio/gpio-mt7621.c
+++ b/drivers/gpio/gpio-mt7621.c
@@ -187,6 +187,8 @@ mediatek_gpio_irq_type(struct irq_data *d, unsigned int type)
 	struct mtk_gc *rg = gpiochip_get_data(gc);
 	u32 mask = BIT(mt7621_gpio_hwirq_to_offset(d->hwirq, rg));
 
+	guard(gpio_generic_lock_irqsave)(&rg->chip);
+
 	if (type == IRQ_TYPE_PROBE) {
 		if ((rg->rising | rg->falling |
 		     rg->hlevel | rg->llevel) & mask)
-- 
2.43.0