Pico W Occasional Crash in cyw43_arch_deinit

[gazzyt]

I have an application using SDK 2.1.0 that does the following:

• reads some sensors
• joins the wifi network
• publish the readings to mqtt
• disconnect from the wifi network
• sleep for 10 mins
• repeat for ever

Source code is here: https://github.com/gazzyt/pico-weather-mqtt

This is using pico_cyw43_arch_lwip_threadsafe_background mode of the networking stack.

The application runs fine mostly but I had the following issue after about 150 cycles.
I can't see anything in my code that could cause this so I suspect a timing issue in the SDK code. It looks to me like the maybe background irq is being fired during the time that it is being removed although I really don't understand the SDK code in detail.

Stacktrace:

unhandled_user_irq_num_in_r0 () at /home/pi/pico/pico-sdk/src/rp2_common/pico_crt0/crt0.S:289
289         bkpt #0
(gdb) bt
#0  unhandled_user_irq_num_in_r0 () at /home/pi/pico/pico-sdk/src/rp2_common/pico_crt0/crt0.S:289
#1  <signal handler called>
#2  0x1000153c in set_raw_irq_handler_and_unlock (num=num@entry=13, handler=handler@entry=0x100001cd <isr_irq9>, save=save@entry=0)
    at /home/pi/pico/pico-sdk/src/rp2_common/hardware_irq/irq.c:59
#3  0x1000194c in irq_remove_handler (num=num@entry=13, handler=handler@entry=0x10013d01 <cyw43_gpio_irq_handler>)
    at /home/pi/pico/pico-sdk/src/rp2_common/hardware_irq/irq.c:575
#4  0x1000129e in gpio_remove_raw_irq_handler_masked (gpio_mask=gpio_mask@entry=16777216, handler=handler@entry=0x10013d01 <cyw43_gpio_irq_handler>)
    at /home/pi/pico/pico-sdk/src/rp2_common/hardware_gpio/gpio.c:243
#5  0x10013d5c in gpio_remove_raw_irq_handler (handler=<optimized out>, gpio=24)
    at /home/pi/pico/pico-sdk/src/rp2_common/hardware_gpio/include/hardware/gpio.h:819
#6  cyw43_irq_deinit (param=<optimized out>) at /home/pi/pico/pico-sdk/src/rp2_common/pico_cyw43_driver/cyw43_driver.c:66
#7  0x10014174 in async_context_threadsafe_background_execute_sync (self_base=0x20002348 <cyw43_async_context_threadsafe_background>,
    func=0x10013d41 <cyw43_irq_deinit>, param=0x0)
    at /home/pi/pico/pico-sdk/src/rp2_common/pico_async_context/async_context_threadsafe_background.c:156
#8  0x10013e5e in async_context_execute_sync (param=0x0, func=<optimized out>, context=0x20002348 <cyw43_async_context_threadsafe_background>)
    at /home/pi/pico/pico-sdk/src/rp2_common/pico_async_context/include/pico/async_context.h:256
#9  cyw43_driver_deinit (context=context@entry=0x20002348 <cyw43_async_context_threadsafe_background>)
    at /home/pi/pico/pico-sdk/src/rp2_common/pico_cyw43_driver/cyw43_driver.c:121
#10 0x100103bc in cyw43_arch_deinit () at /home/pi/pico/pico-sdk/src/rp2_common/pico_cyw43_arch/cyw43_arch_threadsafe_background.c:70
#11 0x10000bc4 in WifiConnection::~WifiConnection (this=this@entry=0x20041a34, __in_chrg=<optimized out>)
    at /home/pi/dev/pico-weather-mqtt/wifi_connection.cpp:44
#12 0x1000043a in publish_sensor_values (values=...) at /usr/include/newlib/c++/12.2.1/bits/new_allocator.h:90
#13 0x10000766 in main () at /home/pi/dev/pico-weather-mqtt/uvsensor.cpp:138

Is this my code at fault or have I hit an SDK bug?

[peterharperuk]

I feel like I've seen this before, but I can't reproduce it. I would guess it's an sdk bug. It strikes me that cyw43_irq_deinit is doing things in the wrong order. Are you able to try moving the call to cyw43_set_irq_enabled in cyw43_irq_deinit so it's called before gpio_remove_raw_irq_handler?

uint32_t cyw43_irq_deinit(__unused void *param) {
#ifndef NDEBUG
    assert(get_core_num() == async_context_core_num(cyw43_async_context));
#endif
    gpio_remove_raw_irq_handler(CYW43_PIN_WL_HOST_WAKE, cyw43_gpio_irq_handler);
    cyw43_set_irq_enabled(false); // MOVE THIS SO IT'S CALLED BEFORE gpio_remove_raw_irq_handler
    return 0;
}

[gazzyt]

Yep - I've made that change and it's now running on the PICO. I'll update you in a couple of days unless it crashes sooner.

Thanks,
Gary

[gazzyt]

It's been solid for a couple of days now so I reckon this was the fix. I have submitted a PR with the change.

Thanks for the help!

[peterharperuk]

Nice!