fix(threadx): fix clock scaling math and TCB memory leak in system.c

[michael545]

Description

What does this PR do?

This PR resolves two critical ThreadX PAL issues in src/system/threadx/stm32/system.c:

1. Clock Math Integer Truncation: __z_clock_gettime() and _z_get_time_since_epoch() evaluated (TX_TIMER_TICKS_PER_SECOND / 1000) first. For 2000Hz tick rates, 2000 / 1000 = 2, accelerating reported time by 4x. For <=500Hz tick rates, 500 / 1000 = 0, freezing time at 0. This PR updates __z_clock_gettime() to calculate seconds by ticks / TX_TIMER_TICKS_PER_SECOND and nanoseconds via remainder modulus.
2. Task Control Block Memory Leak: _z_task_join() waited for task completion (TX_COMPLETED), but omitted tx_thread_delete(). On session reconnection, _z_task_init() invoked tx_thread_create() on the existing TCB, failing with 0x0E (TX_THREAD_ERROR). This PR adds tx_thread_delete(&(task->threadx_thread)) in _z_task_join().

Related Issues

• Fixes [Bug] ThreadX __z_clock_gettime has broken time logic #1233
• Fixes [Bug] ThreadX PAL _z_task_join does not delete completed thread, causing tx_thread_create failure on reconnect #1273

Signed-off-by: michael545 michael.valand@gmail.com

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Labels: bug

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Pull request overview

This PR fixes timekeeping and task lifecycle issues in the ThreadX STM32 platform layer (src/system/threadx/stm32/system.c) to ensure correct clock scaling across tick rates and to prevent ThreadX thread control blocks (TCBs) from being left in a non-reusable state after task completion.

Changes:

• Fixes __z_clock_gettime() time conversion by computing seconds + fractional nanoseconds from ticks without integer-truncation artifacts.
• Ensures _z_task_join() deletes the underlying ThreadX thread so the TCB can be reused after reconnect.
• Fixes additional tick-to-time conversions (_z_condvar_wait_until(), z_time_elapsed_s(), _z_get_time_since_epoch()), and implements _z_task_cancel() using ThreadX termination.

Suppressed comments (1)

src/system/threadx/stm32/system.c:105

• _z_task_cancel() terminates the thread but never deletes it. For ThreadX, tx_thread_terminate() does not remove the thread control block from kernel lists; without a subsequent tx_thread_delete(), the same TCB reuse/reconnect failure can still happen when cancel is used (similar to the original join leak).

z_result_t _z_task_cancel(_z_task_t *task) {
    UINT status = tx_thread_terminate(&(task->threadx_thread));
    if (status != TX_SUCCESS && status != TX_THREAD_ERROR) {
        _Z_ERROR_RETURN(_Z_ERR_GENERIC);
    }
    return _Z_RES_OK;
}

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