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Annotation of OSKit-Mach/oskit/ds_request.c, revision 1.1.1.1

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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