Function ktrprocfork

freebsd/kern/kern_ktrace.c:582–607

* When a process forks, enable tracing in the new process if needed. */

 * When a process forks, enable tracing in the new process if needed.
 */
void
ktrprocfork(struct proc *p1, struct proc *p2)
{

	MPASS(p2->p_tracevp == NULL);
	MPASS(p2->p_traceflag == 0);

	if (p1->p_traceflag == 0)
		return;

	PROC_LOCK(p1);
	mtx_lock(&ktrace_mtx);
	if (p1->p_traceflag & KTRFAC_INHERIT) {
		p2->p_traceflag = p1->p_traceflag;
		if ((p2->p_tracevp = p1->p_tracevp) != NULL) {
			VREF(p2->p_tracevp);
			KASSERT(p1->p_tracecred != NULL,
			    ("ktrace vnode with no cred"));
			p2->p_tracecred = crhold(p1->p_tracecred);
		}
	}
	mtx_unlock(&ktrace_mtx);
	PROC_UNLOCK(p1);

	ktrprocctor(p2);
}

/*
 * When a thread returns, drain any asynchronous records generated by the