[PATCH 7.1 004/271] gpio: pca953x: fix pca953x_irq_bus_sync_unlock regmap lock

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Tomlinson <[email protected]>

[ Upstream commit 9dc325327babe7f159e84cbe9380a45342da0585 ]

Locking is disabled in the regmap config as this driver uses its own
lock. This means that all calls to regmap functions (read or write) must
hold the i2c_lock. The function pca953x_irq_bus_sync_unlock() did not do
this, and it was therefore possible that multiple threads could cause an
incorrect register to be read/written.

A previous patch partly fixed this, but only protected the write to the
interrupt mask register, and not the read from the direction register.

Fixes: bfc6444b57dc ("gpio: pca953x: fix pca953x_irq_bus_sync_unlock race")
Cc: [email protected]
Signed-off-by: Mark Tomlinson <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Bartosz Golaszewski <[email protected]>
(cherry picked from commit 9dc325327babe7f159e84cbe9380a45342da0585)
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/gpio/gpio-pca953x.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 69c5bd9aaee7c..cb282b35fb58d 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -605,20 +605,28 @@ static int pca953x_read_regs(struct pca953x_chip *chip, int reg, unsigned long *
 	return 0;
 }
 
-static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+static int pca953x_gpio_direction_input_unlocked(struct gpio_chip *gc,
+						 unsigned int off)
 {
 	struct pca953x_chip *chip = gpiochip_get_data(gc);
 	u8 dirreg = chip->recalc_addr(chip, chip->regs->direction, off);
 	u8 bit = pca953x_get_bit_mask(chip, off);
 
-	guard(mutex)(&chip->i2c_lock);
-
 	if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)
 		return regmap_update_bits(chip->regmap, dirreg, bit, 0);
 
 	return regmap_update_bits(chip->regmap, dirreg, bit, bit);
 }
 
+static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned int off)
+{
+	struct pca953x_chip *chip = gpiochip_get_data(gc);
+
+	guard(mutex)(&chip->i2c_lock);
+
+	return pca953x_gpio_direction_input_unlocked(gc, off);
+}
+
 static int pca953x_gpio_direction_output(struct gpio_chip *gc,
 		unsigned off, int val)
 {
@@ -856,9 +864,10 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 	DECLARE_BITMAP(reg_direction, MAX_LINE);
 	int level;
 
+	guard(mutex)(&chip->i2c_lock);
+
 	if (chip->driver_data & PCA_PCAL) {
 		DECLARE_BITMAP(latched_inputs, MAX_LINE);
-		guard(mutex)(&chip->i2c_lock);
 
 		/* Enable latch on edge-triggered interrupt-enabled inputs */
 		bitmap_or(latched_inputs, chip->irq_trig_fall, chip->irq_trig_raise, gc->ngpio);
@@ -882,7 +891,7 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 
 	/* Look for any newly setup interrupt */
 	for_each_set_bit(level, irq_mask, gc->ngpio)
-		pca953x_gpio_direction_input(&chip->gpio_chip, level);
+		pca953x_gpio_direction_input_unlocked(&chip->gpio_chip, level);
 
 	mutex_unlock(&chip->irq_lock);
 }
-- 
2.53.0