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Annotation of OSKit-Mach/oskit/ds_request.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1993,1991,1990,1989,1988 Carnegie Mellon University
        !             4:  * All Rights Reserved.
        !             5:  *
        !             6:  * Permission to use, copy, modify and distribute this software and its
        !             7:  * documentation is hereby granted, provided that both the copyright
        !             8:  * notice and this permission notice appear in all copies of the
        !             9:  * software, derivative works or modified versions, and any portions
        !            10:  * thereof, and that both notices appear in supporting documentation.
        !            11:  *
        !            12:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            13:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            14:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            15:  *
        !            16:  * Carnegie Mellon requests users of this software to return to
        !            17:  *
        !            18:  *  Software Distribution Coordinator  or  [email protected]
        !            19:  *  School of Computer Science
        !            20:  *  Carnegie Mellon University
        !            21:  *  Pittsburgh PA 15213-3890
        !            22:  *
        !            23:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            24:  * the rights to redistribute these changes.
        !            25:  */
        !            26: 
        !            27: #include "ds_request.h"
        !            28: 
        !            29: #include <machine/spl.h>
        !            30: #include <kern/counters.h>
        !            31: #include <kern/queue.h>
        !            32: #include <kern/zalloc.h>
        !            33: 
        !            34: 
        !            35: queue_head_t           device_ready_queue;
        !            36: decl_simple_lock_data(,        device_ready_queue_lock)
        !            37: 
        !            38: zone_t io_req_zone;
        !            39: 
        !            40: 
        !            41: void io_done_thread_continue()
        !            42: {
        !            43:        for (;;) {
        !            44:            register spl_t      s;
        !            45:            device_t dev;
        !            46: 
        !            47:            while (1)
        !            48:              {
        !            49:                s = splio();
        !            50:                simple_lock(&device_ready_queue_lock);
        !            51: 
        !            52:                if (queue_empty (&device_ready_queue))
        !            53:                  break;
        !            54:                queue_remove_first (&device_ready_queue, dev,
        !            55:                                    device_t, com.stream.ready_queue);
        !            56: 
        !            57:                /* Clear this link to indicate that the device is no
        !            58:                   longer on the queue, so ds_device_ready (below)
        !            59:                   can check and avoid trying to requeue a device
        !            60:                   that is already waiting for us on the queue.  */
        !            61:                dev->com.stream.ready_queue.next = 0;
        !            62: 
        !            63:                simple_unlock(&device_ready_queue_lock);
        !            64:                (void) splx(s);
        !            65: 
        !            66:                /* We have a ready device.  */
        !            67:                ds_asyncio_ready (dev);/* could be dev->ops->ready */
        !            68:                device_deallocate (dev); /* place on ready queue held a ref */
        !            69:            }
        !            70: 
        !            71:            assert_wait(&device_ready_queue, FALSE);
        !            72:            simple_unlock(&device_ready_queue_lock);
        !            73:            (void) splx(s);
        !            74:            counter(c_io_done_thread_block++);
        !            75:            thread_block(io_done_thread_continue);
        !            76:        }
        !            77: }
        !            78: 
        !            79: void io_done_thread()
        !            80: {
        !            81:        /*
        !            82:         * Set thread privileges and highest priority.
        !            83:         */
        !            84:        current_thread()->vm_privilege = TRUE;
        !            85:        stack_privilege(current_thread());
        !            86:        thread_set_own_priority(0);
        !            87: 
        !            88:        io_done_thread_continue();
        !            89:        /*NOTREACHED*/
        !            90: }
        !            91: 
        !            92: 
        !            93: void
        !            94: ds_device_ready (device_t dev)
        !            95: {
        !            96:   spl_t s;
        !            97:   int ref;
        !            98: 
        !            99:   s = splio ();
        !           100:   simple_lock (&device_ready_queue_lock); /* locks all request queues! */
        !           101: 
        !           102:   ref = (dev->com.stream.ready_queue.next == 0);
        !           103:   if (ref)                     /* if not already on the queue */
        !           104:     queue_enter (&device_ready_queue, dev, device_t, com.stream.ready_queue);
        !           105: 
        !           106:   simple_unlock (&device_ready_queue_lock);
        !           107:   splx (s);
        !           108: 
        !           109:   /* The device's spot on the ready queue holds a reference that
        !           110:      will be freed when it's dequeued.  */
        !           111:   device_reference (dev);
        !           112: 
        !           113:   thread_wakeup_one (&device_ready_queue);
        !           114: }
        !           115: 
        !           116: void
        !           117: ds_request_init (void)
        !           118: {
        !           119:   io_req_zone = zinit (sizeof (struct pending_request),
        !           120:                       1000 * sizeof (struct pending_request),
        !           121:                       100 * sizeof (struct pending_request),
        !           122:                       ZONE_EXHAUSTIBLE,
        !           123:                       "io requests pending");
        !           124: 
        !           125:   queue_init (&device_ready_queue);
        !           126:   simple_lock_init (&device_ready_queue_lock);
        !           127: }

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