[PATCH 5.15.y] gpio: mt7621: avoid corruption of shared interrupt trigger state

[Sasha Levin <sashal@kernel.org>]

From: Sergio Paracuellos <sergio.paracuellos@gmail.com>

[ Upstream commit 1781172526d1092323af443fa03f00e6de560401 ]

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.

Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Fixes: 4ba9c3afda41 ("gpio: mt7621: Add a driver for MT7621")
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://patch.msgid.link/20260626060112.2498324-2-sergio.paracuellos@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
[ Changed `guard(gpio_generic_lock_irqsave)(&rg->chip)` to `guard(spinlock_irqsave)(&rg->lock)` as the generic GPIO chip lock does not exist in this tree. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 c3658a597a80a0..bf08f6894ae063 100644
--- a/drivers/gpio/gpio-mt7621.c
+++ b/drivers/gpio/gpio-mt7621.c
@@ -153,6 +153,8 @@ mediatek_gpio_irq_type(struct irq_data *d, unsigned int type)
 	int pin = d->hwirq;
 	u32 mask = BIT(pin);
 
+	guard(spinlock_irqsave)(&rg->lock);
+
 	if (type == IRQ_TYPE_PROBE) {
 		if ((rg->rising | rg->falling |
 		     rg->hlevel | rg->llevel) & mask)
-- 
2.53.0