Fix gpio-fsm race condition #5596
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Move some functions into a more logical ordering. This change causes no functional change and is essentially cosmetic. Signed-off-by: Phil Elwell <[email protected]>
Partition the code to separate atomic and non-atomic methods so that none of them have to handle both cases. The result avoids using deferred work unless necessary, and should be easier to understand. Signed-off-by: Phil Elwell <[email protected]>
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kernel: Fix gpio-fsm race condition See: raspberrypi/linux#5596
popcornmix
added a commit
to raspberrypi/rpi-firmware
that referenced
this pull request
Sep 8, 2023
kernel: Fix gpio-fsm race condition See: raspberrypi/linux#5596
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Under certain circumstances (building the gpio-fsm module into the kernel seems to be a factor), it is possible for a gpio-fsm soft GPIO to be driven before the FSM has entered its start state, causing a crash. Partition the code more carefully into that which can sleep (non-atomic) and that which can't (atomic), avoiding using the workqueue unless trying to drive GPIOs from atomic code. With this done, it becomes clear that the probe function can just call the non-atomic
gpio_fsm_enter_statedirectly.