5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ian Ray ian.ray@gehealthcare.com
[ 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@gehealthcare.com Link: https://lore.kernel.org/r/20240620042915.2173-1-ian.ray@gehealthcare.com Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpio-pca953x.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index c81d73d5e0159..d4c81373929af 100644 --- a/drivers/gpio/gpio-pca953x.c +++ b/drivers/gpio/gpio-pca953x.c @@ -696,6 +696,8 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d) pca953x_read_regs(chip, chip->regs->direction, reg_direction);
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);