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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 #pragma ident	"%Z%%M%	%I%	%E% SMI"	/* from SVr4.0 1.15 */
     31 
     32 #include <sys/types.h>
     33 #include <sys/param.h>
     34 #include <sys/sysmacros.h>
     35 #include <sys/systm.h>
     36 #include <sys/errno.h>
     37 #include <sys/cred.h>
     38 #include <sys/proc.h>
     39 #include <sys/debug.h>
     40 #include <sys/class.h>
     41 #include <sys/mutex.h>
     42 #include <sys/schedctl.h>
     43 
     44 /*
     45  * We support the nice system call for compatibility although
     46  * the priocntl system call supports a superset of nice's functionality.
     47  * We support nice only for time sharing threads.  It will fail
     48  * if called by a thread from another class.
     49  */
     50 
     51 int
     52 nice(int niceness)
     53 {
     54 	int error = 0;
     55 	int err, retval;
     56 	kthread_t *t;
     57 	proc_t *p = curproc;
     58 
     59 	mutex_enter(&p->p_lock);
     60 	t = p->p_tlist;
     61 	do {
     62 		err = CL_DONICE(t, CRED(), niceness, &retval);
     63 		schedctl_set_cidpri(t);
     64 		if (error == 0 && err)
     65 			error = set_errno(err);
     66 	} while ((t = t->t_forw) != p->p_tlist);
     67 	mutex_exit(&p->p_lock);
     68 	if (error)
     69 		return (error);
     70 	return (retval);
     71 }
     72