Function thread_check_susp

freebsd/kern/kern_thread.c:1431–1453

* Check for possible stops and suspensions while executing a * casueword or similar transiently failing operation. * * The sleep argument controls whether the function can handle a stop * request itself or it should return ERESTART and the request is * proceed at the kernel/user boundary in ast. * * Typically, when retrying due to casueword(9) failure (rv == 1), we * should handle the stop

 * handle it at all, and simply return EINTR.
 */
int
thread_check_susp(struct thread *td, bool sleep)
{
	struct proc *p;
	int error;

	/*
	 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to
	 * eventually break the lockstep loop.
	 */
	if ((td->td_flags & TDF_NEEDSUSPCHK) == 0)
		return (0);
	error = 0;
	p = td->td_proc;
	PROC_LOCK(p);
	if (p->p_flag & P_SINGLE_EXIT)
		error = EINTR;
	else if (P_SHOULDSTOP(p) ||
	    ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND)))
		error = sleep ? thread_suspend_check(0) : ERESTART;
	PROC_UNLOCK(p);
	return (error);
}

void
thread_suspend_switch(struct thread *td, struct proc *p)