]> git.hungrycats.org Git - linux/commit
gpio: pca953x: fix pca953x_irq_bus_sync_unlock race
authorIan Ray <ian.ray@gehealthcare.com>
Thu, 20 Jun 2024 04:29:15 +0000 (07:29 +0300)
committerBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Fri, 21 Jun 2024 14:20:34 +0000 (16:20 +0200)
commitbfc6444b57dc7186b6acc964705d7516cbaf3904
tree41224deba7ad3edd0df17c339fb2c4231d20a4cd
parent83a7eefedc9b56fe7bfeff13b6c7356688ffa670
gpio: pca953x: fix pca953x_irq_bus_sync_unlock race

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>
drivers/gpio/gpio-pca953x.c