when running under FreeRTOS SMP, the timer task can attempt to free the CYW43 async context's statically allocated timer

[vogon]

hey there. while running FreeRTOS SMP 11.2.0 on SDK version 2.2.0 with static allocation enabled, I ran into an issue where calling cyw43_arch_deinit from a FreeRTOS task would cause FreeRTOS to throw an assertion failure and hard fault:

assertion "( ( uint8_t * ) ( pxLink ) >= &( ucHeap[ 0 ] ) ) && ( ( uint8_t * ) ( pxLink ) <= &( ucHeap[ (128*1024) - 1 ] ) )" failed: file "/home/vogon/work/ais-epaper/build/freertos_kernel-src/portable/MemMang/heap_4.c", line 368, function: vPortFree

I think the series of events which precipitates this assertion failing are:

1. async_context_freertos_deinit calls xTimerDelete on the async context's associated timer, which enqueues an asynchronous timer delete command for the timer task.
2. async_context_freertos_deinit continues executing past the memset at the end of the function.
3. the timer task is scheduled and receives the command from async_context_freertos_deinit to delete the timer.
4. prvProcessReceivedCommands checks pxTimer->ucStatus, which has been cleared to 0, and decides the timer was dynamically allocated.
5. vPortFree notices that the statically-allocated timer isn't in a heap block and panics.

I've verified that commenting out the memset at the bottom of async_context_freertos_deinit (which seems to be redundant with a memset at the top of async_context_freertos_init) prevents the crash from happening.

I've uploaded a gist of the app I'm running (with all the commented-out code removed but otherwise not cleaned up), as well as my FreeRTOSConfig.h and CMakeLists.txt: https://gist.github.com/vogon/4c08fdd31a565609d02cb2534a4386bd