This is a note to let you know that I've just added the patch titled
gpio: pca953x: fix pca953x_irq_bus_sync_unlock race
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpio-pca953x-fix-pca953x_irq_bus_sync_unlock-race.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b8b5a7f210780d8d7ffd6efe0339756db7c8b58e
Author: Ian Ray <ian.ray@xxxxxxxxxxxxxxxx>
Date: Thu Jun 20 07:29:15 2024 +0300
gpio: pca953x: fix pca953x_irq_bus_sync_unlock race
[ Upstream commit bfc6444b57dc7186b6acc964705d7516cbaf3904 ]
Ensure that `i2c_lock' is held when setting interrupt latch and mask in
pca953x_irq_bus_sync_unlock() in order to avoid races.
The other (non-probe) call site pca953x_gpio_set_multiple() ensures the
lock is held before calling pca953x_write_regs().
The problem occurred when a request raced against irq_bus_sync_unlock()
approximately once per thousand reboots on an i.MX8MP based system.
* Normal case
0-0022: write register AI|3a {03,02,00,00,01} Input latch P0
0-0022: write register AI|49 {fc,fd,ff,ff,fe} Interrupt mask P0
0-0022: write register AI|08 {ff,00,00,00,00} Output P3
0-0022: write register AI|12 {fc,00,00,00,00} Config P3
* Race case
0-0022: write register AI|08 {ff,00,00,00,00} Output P3
0-0022: write register AI|08 {03,02,00,00,01} *** Wrong register ***
0-0022: write register AI|12 {fc,00,00,00,00} Config P3
0-0022: write register AI|49 {fc,fd,ff,ff,fe} Interrupt mask P0
Signed-off-by: Ian Ray <ian.ray@xxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240620042915.2173-1-ian.ray@xxxxxxxxxxxxxxxx
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index dc4088a47ab2d..5dcc31e5fb3eb 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -489,6 +489,8 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
u8 invert_irq_mask[MAX_BANK];
if (chip->driver_data & PCA_PCAL) {
+ guard(mutex)(&chip->i2c_lock);
+
/* Enable latch on interrupt-enabled inputs */
pca953x_write_regs(chip, PCAL953X_IN_LATCH, chip->irq_mask);
