esp32/machine_uart: Correctly manage UART queue and event task. #17135
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DvdGiessen
commented
Apr 16, 2025
dpgeorge
reviewed
May 14, 2025
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If the driver was reinitialised while there was already an event task running the queue that task is trying to receive from would be deleted, causing it to try to take a lock that no longer existed and deadlocking the CPU. This change ensures the task is always shut down before recreating the queue and recreates the task afterwards. It also allows setting an IRQ handler before the UART is initialized (like other ports allow), removes the task when the UART is deinitialized (which was previously missing), adds a check that no event task can be started when no queue exists, and adds a check to prevent reinitialising the UART driver unnecessarily. Signed-off-by: Daniël van de Giessen <daniel@dvdgiessen.nl>
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dpgeorge
approved these changes
May 15, 2025
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Summary
If the driver was reinitialised while there was already an event task running the queue that task is trying to receive from would be deleted, causing it to try to take a lock that no longer existed and deadlocking the CPU.
This change ensures the task is always shut down before recreating the queue and recreates the task afterwards.
It also:
Testing
Tested on three custom boards (1x original ESP32, 2x ESP32S3) to talk to three modem chips (1x Sequans, 2x different SIMCOM) all using the UART IRQ's to trigger the PPP.poll() method.