chprio.c,v

来自「TCP-IP红宝书源代码」· C,V 代码 · 共 62 行

head	1.1;
access;
symbols;
locks
	dls:1.1; strict;
comment	@ * @;


1.1
date	97.09.21.19.29.30;	author dls;	state Dist;
branches;
next	;


desc
@@


1.1
log
@pre-3e code
@
text
@/* chprio.c - chprio */

#include <conf.h>
#include <kernel.h>
#include <proc.h>

/*------------------------------------------------------------------------
 * chprio  --  change the scheduling priority of a process
 *------------------------------------------------------------------------
 */
SYSCALL chprio(pid,newprio)
	int	pid;
	int	newprio;		/* newprio > 0			*/
{
	STATWORD ps;    
	int	oldprio;
	struct	pentry	*pptr;

	disable(ps);
	if (isbadpid(pid) || newprio<=0 ||
	    (pptr = &proctab[pid])->pstate == PRFREE) {
		restore(ps);
		return(SYSERR);
	}
	oldprio = pptr->pprio;
	pptr->pprio = newprio;
	switch (pptr->pstate) {
	case PRREADY:
		insert( dequeue(pid), rdyhead, newprio);
	case PRCURR:
		resched();
	default:
		break;
	}
	restore(ps);
	return(oldprio);
}
@