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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, Version 1.0 only
      6  * (the "License").  You may not use this file except in compliance
      7  * with the License.
      8  *
      9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
     10  * or http://www.opensolaris.org/os/licensing.
     11  * See the License for the specific language governing permissions
     12  * and limitations under the License.
     13  *
     14  * When distributing Covered Code, include this CDDL HEADER in each
     15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     16  * If applicable, add the following below this CDDL HEADER, with the
     17  * fields enclosed by brackets "[]" replaced with your own identifying
     18  * information: Portions Copyright [yyyy] [name of copyright owner]
     19  *
     20  * CDDL HEADER END
     21  */
     22 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
     23 /*	  All Rights Reserved  	*/
     24 /*	Copyright (c) 1994 Sun Microsystems, Inc. */
     25 
     26 
     27 #pragma ident	"@(#)nice.c	1.4	05/06/08 SMI"	/* from SVr4.0 1.15 */
     28 
     29 #include <sys/types.h>
     30 #include <sys/param.h>
     31 #include <sys/sysmacros.h>
     32 #include <sys/systm.h>
     33 #include <sys/errno.h>
     34 #include <sys/cred.h>
     35 #include <sys/proc.h>
     36 #include <sys/debug.h>
     37 #include <sys/class.h>
     38 #include <sys/mutex.h>
     39 
     40 /*
     41  * We support the nice system call for compatibility although
     42  * the priocntl system call supports a superset of nice's functionality.
     43  * We support nice only for time sharing threads.  It will fail
     44  * if called by a thread from another class.
     45  */
     46 
     47 int
     48 nice(int niceness)
     49 {
     50 	int error = 0;
     51 	int err, retval;
     52 	kthread_id_t t;
     53 	proc_t	*p = curproc;
     54 
     55 	mutex_enter(&p->p_lock);
     56 	t = p->p_tlist;
     57 	do {
     58 		err = CL_DONICE(t, CRED(), niceness, &retval);
     59 		if (error == 0 && err)
     60 			error = set_errno(err);
     61 	} while ((t = t->t_forw) != p->p_tlist);
     62 	mutex_exit(&p->p_lock);
     63 	if (error)
     64 		return (error);
     65 	return (retval);
     66 }
     67