Process cleanup semantics

[FlareCoding]

Add proc_kill syscall and implement recursive process termination on parent exit or explicit kill.

This PR addresses the need for robust process management by ensuring that child processes are properly terminated when their parent exits without waiting, or when explicitly killed, preventing orphaned processes and kernel panics.

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Missing __PRIVILEGED_CODE on do_exit_current

High Severity · Logic Bug

do_exit_current was extracted from inline code inside a RUN_ELEVATED block in sched::exit(), but the new standalone function lacks the __PRIVILEGED_CODE annotation. It is called directly from maybe_terminate_current() which IS __PRIVILEGED_CODE, and it itself calls privileged functions like sync::spin_lock_irqsave, sync::wake_all, and store_cleanup_stage. This function needs __PRIVILEGED_CODE to be placed in the privileged code section, matching the annotation pattern of every other static helper in this file that touches scheduler/sync internals.

 

[cursor]

TOCTOU race in terminate vs wait entry

Medium Severity · Potential Edge Case

request_terminate reads t->state without holding the target wait queue's lock. If the target task is between the termination_requested check in sync::wait and setting its state to TASK_STATE_BLOCKED, request_terminate sees RUNNING, skips the cancel_wait/cancel_sleep, and returns. The task then enters blocked state with terminate_requested already set. It stays blocked until whatever it's waiting on fires naturally — if that event never arrives (e.g., blocked on I/O or an unrelated wait queue), the task is stuck and terminate_proc_resource_with_epoch deadlocks waiting for pr->exited.

Additional Locations (1)

• kernel/sync/wait_queue.cpp#L19-L34