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2 | pj | 1 | /* |
2 | * Project: S.Ha.R.K. |
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3 | * |
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4 | * Coordinators: |
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5 | * Giorgio Buttazzo <giorgio@sssup.it> |
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6 | * Paolo Gai <pj@gandalf.sssup.it> |
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7 | * |
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8 | * Authors : |
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9 | * Paolo Gai <pj@gandalf.sssup.it> |
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10 | * Massimiliano Giorgi <massy@gandalf.sssup.it> |
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11 | * Luca Abeni <luca@gandalf.sssup.it> |
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12 | * (see the web pages for full authors list) |
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13 | * |
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14 | * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy) |
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15 | * |
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16 | * http://www.sssup.it |
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17 | * http://retis.sssup.it |
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18 | * http://shark.sssup.it |
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19 | */ |
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20 | |||
21 | |||
22 | /** |
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23 | ------------ |
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24 | CVS : $Id: srp.h,v 1.1.1.1 2002-03-29 14:12:51 pj Exp $ |
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25 | |||
26 | File: $File$ |
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27 | Revision: $Revision: 1.1.1.1 $ |
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28 | Last update: $Date: 2002-03-29 14:12:51 $ |
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29 | ------------ |
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30 | |||
31 | This file contains the Stack Resource Policy (SRP) Protocol |
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32 | |||
33 | Title: |
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34 | SRP (Stack Resource Policy) |
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35 | |||
36 | Resource Models Accepted: |
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37 | None |
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38 | |||
39 | Description: |
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40 | This module implement the Stack Resource policy using the shadow field |
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41 | of the task descriptor. No difference is made upon the task model of the |
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42 | tasks that use SRP mutexes. |
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43 | |||
44 | A SRP mutex is created passing the SRP_mutexattr structure to mutex_init. |
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45 | |||
46 | In effect, this module doesn't work correctly if it is |
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47 | used, for example, with a Round Robin Module; in this case we |
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48 | can have a task B that preempts A, but when B finishes his timeslice, A |
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49 | can be scheduled by the RR module, and the SRP can't block it, because |
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50 | the SRP module can not control preemptions (it works only using the shadow |
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51 | field at lock and unlock time!!!). |
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52 | Note that this problen not affect the EDF, RM & co. algorithms... because |
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53 | if B preempts A, A will never preempts on B... |
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54 | |||
55 | A task that want to use the SRP protocol MUST declare it using a |
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56 | SRP_RES_MODEL in the task_create. Only the first SRP_RES_MODEL is |
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57 | considered. |
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58 | |||
59 | A task that want to use a SRP mutex have to declare it with the |
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60 | SRP_usemutex function as last parameter of a task_create call, AFTER |
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61 | the specification of the preemption level. |
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62 | |||
63 | Exceptions raised: |
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64 | XMUTEX_OWNER_KILLED |
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65 | This exception is raised when a task ends and it owns one or more |
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66 | mutexes |
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67 | |||
68 | XSRP_UNVALID_LOCK |
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69 | This exception is raised when a task try to lock a srp mutex but |
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70 | it don't have the provilege. |
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71 | |||
72 | Restrictions & special features: |
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73 | - This module is NOT Posix compliant |
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74 | - This module can manage any number of SRP mutexes. |
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75 | - If a task ends (because it reaches the end of the body or because it |
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76 | is killed by someone) and it owns some mutex, an exception is raised. |
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77 | - if a mutex unlock is called on a mutex not previously |
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78 | locked or previously locked by another task an exception is raised |
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79 | - A SRP mutex can not be statically allocated |
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80 | - The module is incompatible with the primitive TASK_JOIN, so the tasks |
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81 | that uses SRP can NOT call task_join. |
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82 | **/ |
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83 | |||
84 | /* |
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85 | * Copyright (C) 2000 Paolo Gai |
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86 | * |
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87 | * This program is free software; you can redistribute it and/or modify |
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88 | * it under the terms of the GNU General Public License as published by |
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89 | * the Free Software Foundation; either version 2 of the License, or |
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90 | * (at your option) any later version. |
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91 | * |
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92 | * This program is distributed in the hope that it will be useful, |
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93 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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94 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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95 | * GNU General Public License for more details. |
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96 | * |
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97 | * You should have received a copy of the GNU General Public License |
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98 | * along with this program; if not, write to the Free Software |
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99 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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100 | * |
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101 | */ |
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102 | |||
103 | |||
104 | |||
105 | #ifndef __SRP_H__ |
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106 | #define __SRP_H__ |
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107 | |||
108 | #include <kernel/model.h> |
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109 | #include <kernel/descr.h> |
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110 | |||
111 | void SRP_register_module(void); |
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112 | |||
113 | extern __inline__ RES_MODEL *SRP_usemutex(mutex_t *m) { |
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114 | return (RES_MODEL *)m->opt; |
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115 | }; |
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116 | |||
117 | #endif |