p2->p_cpu = NULL;
p2->p_cpu = p1->p_cpu;
fork1(struct proc *p1, int exitsig, int flags, void *stack, size_t stacksize,    void (*func)(void *), void *arg, register_t *retval,    struct proc **rnewprocp){	struct proc *p2;	uid_t uid;	struct vmspace *vm;	int count;	vaddr_t uaddr;	int s;	extern void endtsleep(void *);	extern void realitexpire(void *);	/*	 * Although process entries are dynamically created, we still keep	 * a global limit on the maximum number we will create. We reserve	 * the last 5 processes to root. The variable nprocs is the current	 * number of processes, maxproc is the limit.	 */	uid = p1->p_cred->p_ruid;	if ((nprocs >= maxproc - 5 && uid != 0) || nprocs >= maxproc) {		static struct timeval lasttfm;		if (ratecheck(&lasttfm, &fork_tfmrate))			tablefull("proc");		return (EAGAIN);	}	nprocs++;	/*	 * Increment the count of procs running with this uid. Don't allow	 * a nonprivileged user to exceed their current limit.	 */	count = chgproccnt(uid, 1);	if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {		(void)chgproccnt(uid, -1);		nprocs--;		return (EAGAIN);	}	/*	 * Allocate a pcb and kernel stack for the process	 */	uaddr = uvm_km_valloc_align(kernel_map, USPACE, USPACE_ALIGN);	if (uaddr == 0) {		chgproccnt(uid, -1);		nprocs--;		return (ENOMEM);	}	/*	 * From now on, we're committed to the fork and cannot fail.	 */	/* Allocate new proc. */	p2 = pool_get(&proc_pool, PR_WAITOK);	p2->p_stat = SIDL;			/* protect against others */	p2->p_exitsig = exitsig;	p2->p_forw = p2->p_back = NULL;	/*	 * Make a proc table entry for the new process.	 * Start by zeroing the section of proc that is zero-initialized,	 * then copy the section that is copied directly from the parent.	 */	bzero(&p2->p_startzero,	    (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));	bcopy(&p1->p_startcopy, &p2->p_startcopy,	    (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));	/*	 * Initialize the timeouts.	 */	timeout_set(&p2->p_sleep_to, endtsleep, p2);	timeout_set(&p2->p_realit_to, realitexpire, p2);#if defined(__HAVE_CPUINFO)	p2->p_cpu = NULL;#endif	/*	 * Duplicate sub-structures as needed.	 * Increase reference counts on shared objects.	 * The p_stats and p_sigacts substructs are set in vm_fork.	 */	p2->p_flag = P_INMEM;	p2->p_emul = p1->p_emul;	if (p1->p_flag & P_PROFIL)		startprofclock(p2);	p2->p_flag |= (p1->p_flag & (P_SUGID | P_SUGIDEXEC));	p2->p_cred = pool_get(&pcred_pool, PR_WAITOK);	bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));	p2->p_cred->p_refcnt = 1;	crhold(p1->p_ucred);	/* bump references to the text vnode (for procfs) */	p2->p_textvp = p1->p_textvp;	if (p2->p_textvp)		VREF(p2->p_textvp);	if (flags & FORK_CLEANFILES)		p2->p_fd = fdinit(p1);	else if (flags & FORK_SHAREFILES)		p2->p_fd = fdshare(p1);	else		p2->p_fd = fdcopy(p1);	/*	 * If p_limit is still copy-on-write, bump refcnt,	 * otherwise get a copy that won't be modified.	 * (If PL_SHAREMOD is clear, the structure is shared	 * copy-on-write.)	 */	if (p1->p_limit->p_lflags & PL_SHAREMOD)		p2->p_limit = limcopy(p1->p_limit);	else {		p2->p_limit = p1->p_limit;		p2->p_limit->p_refcnt++;	}	if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)		p2->p_flag |= P_CONTROLT;	if (flags & FORK_PPWAIT)		p2->p_flag |= P_PPWAIT;	LIST_INSERT_AFTER(p1, p2, p_pglist);	p2->p_pptr = p1;	if (flags & FORK_NOZOMBIE)		p2->p_flag |= P_NOZOMBIE;	LIST_INSERT_HEAD(&p1->p_children, p2, p_sibling);	LIST_INIT(&p2->p_children);#ifdef KTRACE	/*	 * Copy traceflag and tracefile if enabled.	 * If not inherited, these were zeroed above.	 */	if (p1->p_traceflag & KTRFAC_INHERIT) {		p2->p_traceflag = p1->p_traceflag;		if ((p2->p_tracep = p1->p_tracep) != NULL)			VREF(p2->p_tracep);	}#endif	/*	 * set priority of child to be that of parent	 * XXX should move p_estcpu into the region of struct proc which gets	 * copied.	 */	scheduler_fork_hook(p1, p2);	/*	 * Create signal actions for the child process.	 */	if (flags & FORK_SIGHAND)		sigactsshare(p1, p2);	else		p2->p_sigacts = sigactsinit(p1);	/*	 * If emulation has process fork hook, call it now.	 */	if (p2->p_emul->e_proc_fork)		(*p2->p_emul->e_proc_fork)(p2, p1);	/*	 * This begins the section where we must prevent the parent	 * from being swapped.	 */	PHOLD(p1);	p2->p_addr = (struct user *)uaddr;	/*	 * Finish creating the child process.  It will return through a	 * different path later.	 */	uvm_fork(p1, p2, ((flags & FORK_SHAREVM) ? TRUE : FALSE), stack,	    stacksize, func ? func : child_return, arg ? arg : p2);	vm = p2->p_vmspace;	if (flags & FORK_FORK) {		forkstat.cntfork++;		forkstat.sizfork += vm->vm_dsize + vm->vm_ssize;	} else if (flags & FORK_VFORK) {		forkstat.cntvfork++;		forkstat.sizvfork += vm->vm_dsize + vm->vm_ssize;	} else if (flags & FORK_RFORK) {		forkstat.cntrfork++;		forkstat.sizrfork += vm->vm_dsize + vm->vm_ssize;	} else {		forkstat.cntkthread++;		forkstat.sizkthread += vm->vm_dsize + vm->vm_ssize;	}	/* Find an unused pid satisfying 1 <= lastpid <= PID_MAX */	do {		lastpid = 1 + (randompid ? arc4random() : lastpid) % PID_MAX;	} while (pidtaken(lastpid));	p2->p_pid = lastpid;	LIST_INSERT_HEAD(&allproc, p2, p_list);	LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);#if NSYSTRACE > 0	if (ISSET(p1->p_flag, P_SYSTRACE))		systrace_fork(p1, p2);#endif	/*	 * Make child runnable, set start time, and add to run queue.	 */	SCHED_LOCK(s); 	getmicrotime(&p2->p_stats->p_start);	p2->p_acflag = AFORK;	p2->p_stat = SRUN;	setrunqueue(p2);	SCHED_UNLOCK(s);	timeout_set(&p2->p_stats->p_virt_to, virttimer_trampoline, p2);	timeout_set(&p2->p_stats->p_prof_to, proftimer_trampoline, p2);	/*	 * Now can be swapped.	 */	PRELE(p1);	/*	 * Notify any interested parties about the new process.	 */	KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid);	/*	 * Update stats now that we know the fork was successfull.	 */	uvmexp.forks++;	if (flags & FORK_PPWAIT)		uvmexp.forks_ppwait++;	if (flags & FORK_SHAREVM)		uvmexp.forks_sharevm++;	/*	 * Pass a pointer to the new process to the caller.	 */	if (rnewprocp != NULL)		*rnewprocp = p2;	/*	 * Preserve synchronization semantics of vfork.  If waiting for	 * child to exec or exit, set P_PPWAIT on child, and sleep on our	 * proc (in case of exit).	 */	if (flags & FORK_PPWAIT)		while (p2->p_flag & P_PPWAIT)			tsleep(p1, PWAIT, "ppwait", 0);	/*	 * Return child pid to parent process,	 * marking us as parent via retval[1].	 */	if (retval != NULL) {		retval[0] = p2->p_pid;		retval[1] = 0;	}	return (0);}