sched/sched: Fix uninitialized sporadic params returned by nxsched_get_param()

[yushuailong]

Summary

When querying the calling task itself (pid == 0 or the caller's own pid), nxsched_get_param() only filled in sched_priority and never touched the SCHED_SPORADIC related members (sched_ss_low_priority, sched_ss_max_repl, sched_ss_repl_period and sched_ss_init_budget). With CONFIG_SCHED_SPORADIC enabled, the caller received uninitialized stack garbage in these fields, and a task running under the sporadic policy could not retrieve its own sporadic parameters.

Fix this by factoring the sporadic parameter fill-in into a common helper nxsched_get_sporadic_param() shared by both the self-query and the lookup paths, so both paths now return identical information.

The self-query path keeps its original fast-path behavior: no TCB lookup and a lock-free read of sched_priority. Only the read of the sporadic state is wrapped in a critical section, because tcb->sporadic may be freed concurrently, e.g. by sched_setscheduler() from another CPU switching the task away from SCHED_SPORADIC.

Impact

Only affects configurations with CONFIG_SCHED_SPORADIC=y: sched_getparam() / nxsched_get_param() now returns valid sched_ss_* members when a task queries itself, instead of uninitialized stack memory. The sporadic state is read inside a critical section to avoid a race with a concurrent sched_setscheduler(). No API/ABI change; no impact on build, hardware or documentation. Configurations without CONFIG_SCHED_SPORADIC are functionally unchanged.

Testing

ci test

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

• arduino-mega2560
• esp32-devkitc
• hifive1-revb
• mirtoo
• qemu-armv8a
• qemu-intel64
• rx65n-rsk2mb
• s698pm-dkit
• stm32-nucleo-f103rb