Return to syscall_subr.c CVS log

Up to [Apple XNU] / XNU / osfmk / kern

Annotation of XNU/osfmk/kern/syscall_subr.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * @OSF_COPYRIGHT@
        !            24:  */
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
        !            28:  * All Rights Reserved.
        !            29:  * 
        !            30:  * Permission to use, copy, modify and distribute this software and its
        !            31:  * documentation is hereby granted, provided that both the copyright
        !            32:  * notice and this permission notice appear in all copies of the
        !            33:  * software, derivative works or modified versions, and any portions
        !            34:  * thereof, and that both notices appear in supporting documentation.
        !            35:  * 
        !            36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            39:  * 
        !            40:  * Carnegie Mellon requests users of this software to return to
        !            41:  * 
        !            42:  *  Software Distribution Coordinator  or  [email protected]
        !            43:  *  School of Computer Science
        !            44:  *  Carnegie Mellon University
        !            45:  *  Pittsburgh PA 15213-3890
        !            46:  * 
        !            47:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            48:  * the rights to redistribute these changes.
        !            49:  */
        !            50: /*
        !            51:  */
        !            52: 
        !            53: #include <cpus.h>
        !            54: 
        !            55: #include <mach/boolean.h>
        !            56: #include <mach/thread_switch.h>
        !            57: #include <ipc/ipc_port.h>
        !            58: #include <ipc/ipc_space.h>
        !            59: #include <kern/counters.h>
        !            60: #include <kern/etap_macros.h>
        !            61: #include <kern/ipc_kobject.h>
        !            62: #include <kern/processor.h>
        !            63: #include <kern/sched.h>
        !            64: #include <kern/sched_prim.h>
        !            65: #include <kern/spl.h>
        !            66: #include <kern/task.h>
        !            67: #include <kern/thread.h>
        !            68: #include <kern/ast.h>
        !            69: #include <mach/policy.h>
        !            70: 
        !            71: #include <kern/syscall_subr.h>
        !            72: #include <mach/mach_host_server.h>
        !            73: #include <mach/mach_syscalls.h>
        !            74: 
        !            75: #include <kern/sf.h>
        !            76: 
        !            77: /*
        !            78:  *     swtch and swtch_pri both attempt to context switch (logic in
        !            79:  *     thread_block no-ops the context switch if nothing would happen).
        !            80:  *     A boolean is returned that indicates whether there is anything
        !            81:  *     else runnable.
        !            82:  *
        !            83:  *     This boolean can be used by a thread waiting on a
        !            84:  *     lock or condition:  If FALSE is returned, the thread is justified
        !            85:  *     in becoming a resource hog by continuing to spin because there's
        !            86:  *     nothing else useful that the processor could do.  If TRUE is
        !            87:  *     returned, the thread should make one more check on the
        !            88:  *     lock and then be a good citizen and really suspend.
        !            89:  */
        !            90: 
        !            91: swtch_continue()
        !            92: {
        !            93:     boolean_t retval;
        !            94:        register processor_t myprocessor;
        !            95: 
        !            96:     mp_disable_preemption();
        !            97:        myprocessor = current_processor();
        !            98:        retval = (
        !            99: #if    NCPUS > 1
        !           100:               myprocessor->runq.count > 0 ||
        !           101: #endif /*NCPUS > 1*/
        !           102:               myprocessor->processor_set->runq.count > 0);
        !           103:        mp_enable_preemption();
        !           104:        return retval;
        !           105: }
        !           106: 
        !           107: boolean_t
        !           108: swtch(void)
        !           109: {
        !           110:        register processor_t    myprocessor;
        !           111:        boolean_t                               result;
        !           112: 
        !           113:        mp_disable_preemption();
        !           114:        myprocessor = current_processor();
        !           115:        if (
        !           116: #if    NCPUS > 1
        !           117:                        myprocessor->runq.count == 0                                    &&
        !           118: #endif /* NCPUS > 1 */
        !           119:                        myprocessor->processor_set->runq.count == 0                     ) {
        !           120:                mp_enable_preemption();
        !           121: 
        !           122:                return (FALSE);
        !           123:        }
        !           124:        mp_enable_preemption();
        !           125: 
        !           126:        counter(c_swtch_block++);
        !           127: 
        !           128:        thread_block(swtch_continue);
        !           129: 
        !           130:        mp_disable_preemption();
        !           131:        myprocessor = current_processor();
        !           132:        result = 
        !           133: #if    NCPUS > 1
        !           134:                myprocessor->runq.count > 0                                                     ||
        !           135: #endif /*NCPUS > 1*/
        !           136:                myprocessor->processor_set->runq.count > 0;
        !           137:        mp_enable_preemption();
        !           138: 
        !           139:        return (result);
        !           140: }
        !           141: 
        !           142: boolean_t
        !           143: swtch_pri(
        !           144:        int                             pri)
        !           145: {
        !           146:        thread_t                                self = current_thread();
        !           147:        register processor_t    myprocessor;
        !           148:        boolean_t                               result;
        !           149:        sched_policy_t                  *policy;
        !           150:        spl_t                                   s;
        !           151: 
        !           152:        s = splsched();
        !           153:        thread_lock(self);
        !           154:        myprocessor = current_processor();
        !           155:        if (
        !           156: #if    NCPUS > 1
        !           157:                        myprocessor->runq.count == 0                                    &&
        !           158: #endif /* NCPUS > 1 */
        !           159:                        myprocessor->processor_set->runq.count == 0                     ) {
        !           160:                thread_unlock(self);
        !           161:                splx(s);
        !           162: 
        !           163:                return (FALSE);
        !           164:        }
        !           165: 
        !           166:        policy = &sched_policy[self->policy];
        !           167:        thread_unlock(self);
        !           168:        splx(s);
        !           169: 
        !           170:        policy->sp_ops.sp_swtch_pri(policy, pri);
        !           171: 
        !           172:        mp_disable_preemption();
        !           173:        myprocessor = current_processor();
        !           174:        result = 
        !           175: #if    NCPUS > 1
        !           176:                myprocessor->runq.count > 0                                                     ||
        !           177: #endif /*NCPUS > 1*/
        !           178:                myprocessor->processor_set->runq.count > 0;
        !           179:        mp_enable_preemption();
        !           180: 
        !           181:        return (result);
        !           182: }
        !           183: 
        !           184: /*
        !           185:  *     thread_switch:
        !           186:  *
        !           187:  *     Context switch.  User may supply thread hint, if not use
        !           188:  *     the currect thread activation as the hint.  This is the
        !           189:  *     equivilent of providing NULL, but the underlying routines
        !           190:  *     can't handle that anymore.
        !           191:  */
        !           192: kern_return_t
        !           193: thread_switch(
        !           194:        mach_port_name_t                thread_name,
        !           195:        int                                             option,
        !           196:        mach_msg_timeout_t              option_time)
        !           197: {
        !           198:     register thread_t          self = current_thread();
        !           199:     register thread_act_t      thr_act = self->top_act;
        !           200:        sched_policy_t                  *policy;
        !           201:        spl_t                                   s;
        !           202: 
        !           203:     if (thread_name != MACH_PORT_NULL) {
        !           204:                ipc_port_t                      port;
        !           205: 
        !           206:                if (ipc_port_translate_send(thr_act->task->itk_space,
        !           207:                                                                                thread_name, &port) == KERN_SUCCESS) {
        !           208:                        /* port is locked, but it might not be active */
        !           209:                        /*
        !           210:                         *      If it was a valid thread activation, pass that to the
        !           211:                         *  real switching routine, otherwise pass ourself (which
        !           212:                         *  will result in a noop.
        !           213:                         */
        !           214:                        if (ip_active(port) && ip_kotype(port) == IKOT_ACT) {
        !           215:                                thr_act = (thread_act_t) port->ip_kobject;
        !           216:                                (void) act_lock_thread(thr_act);
        !           217:                        }
        !           218: 
        !           219:                        ip_unlock(port);
        !           220:                }
        !           221:        }
        !           222: 
        !           223:        s = splsched();
        !           224:        thread_lock(self);
        !           225:        policy = &sched_policy[self->policy];
        !           226:        thread_unlock(self);
        !           227:        splx(s);
        !           228: 
        !           229:     /*
        !           230:      * This is a scheduling policy-dependent operation.
        !           231:      * Call the routine associated with the thread's
        !           232:      * scheduling policy.
        !           233:      */
        !           234:     return (policy->sp_ops.
        !           235:                                sp_thread_switch(policy, thr_act, option, option_time));
        !           236: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.