1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief POSIX Condition Variables Wait Support |
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5 | * @ingroup POSIX_COND_VARS |
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6 | */ |
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7 | |
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8 | /* |
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9 | * COPYRIGHT (c) 1989-2014. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.rtems.org/license/LICENSE. |
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15 | */ |
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16 | |
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17 | #if HAVE_CONFIG_H |
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18 | #include "config.h" |
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19 | #endif |
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20 | |
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21 | #include <rtems/posix/condimpl.h> |
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22 | #include <rtems/posix/posixapi.h> |
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23 | #include <rtems/score/assert.h> |
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24 | #include <rtems/score/statesimpl.h> |
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25 | #include <rtems/score/status.h> |
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26 | #include <rtems/score/threaddispatch.h> |
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27 | |
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28 | THREAD_QUEUE_OBJECT_ASSERT( POSIX_Condition_variables_Control, Wait_queue ); |
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29 | |
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30 | int _POSIX_Condition_variables_Wait_support( |
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31 | pthread_cond_t *cond, |
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32 | pthread_mutex_t *mutex, |
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33 | Watchdog_Interval timeout, |
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34 | bool already_timedout |
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35 | ) |
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36 | { |
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37 | POSIX_Condition_variables_Control *the_cond; |
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38 | Thread_queue_Context queue_context; |
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39 | int error; |
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40 | int mutex_error; |
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41 | Per_CPU_Control *cpu_self; |
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42 | Thread_Control *executing; |
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43 | |
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44 | if ( mutex == NULL ) { |
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45 | return EINVAL; |
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46 | } |
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47 | |
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48 | the_cond = _POSIX_Condition_variables_Get( cond, &queue_context ); |
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49 | |
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50 | if ( the_cond == NULL ) { |
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51 | return EINVAL; |
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52 | } |
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53 | |
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54 | _POSIX_Condition_variables_Acquire_critical( the_cond, &queue_context ); |
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55 | |
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56 | if ( |
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57 | the_cond->mutex != POSIX_CONDITION_VARIABLES_NO_MUTEX |
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58 | && the_cond->mutex != *mutex |
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59 | ) { |
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60 | _POSIX_Condition_variables_Release( the_cond, &queue_context ); |
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61 | return EINVAL; |
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62 | } |
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63 | |
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64 | the_cond->mutex = *mutex; |
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65 | |
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66 | cpu_self = _Thread_Dispatch_disable_critical( &queue_context.Lock_context ); |
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67 | executing = _Per_CPU_Get_executing( cpu_self ); |
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68 | |
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69 | if ( !already_timedout ) { |
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70 | _Thread_queue_Context_set_expected_level( &queue_context, 2 ); |
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71 | _Thread_queue_Context_set_timeout( &queue_context, timeout ); |
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72 | _Thread_queue_Context_set_discipline( &queue_context, WATCHDOG_RELATIVE ); |
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73 | _Thread_queue_Enqueue_critical( |
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74 | &the_cond->Wait_queue.Queue, |
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75 | POSIX_CONDITION_VARIABLES_TQ_OPERATIONS, |
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76 | executing, |
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77 | STATES_WAITING_FOR_CONDITION_VARIABLE, |
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78 | &queue_context |
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79 | ); |
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80 | } else { |
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81 | _POSIX_Condition_variables_Release( the_cond, &queue_context ); |
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82 | executing->Wait.return_code = STATUS_TIMEOUT; |
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83 | } |
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84 | |
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85 | mutex_error = pthread_mutex_unlock( mutex ); |
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86 | if ( mutex_error != 0 ) { |
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87 | /* |
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88 | * Historically, we ignored the unlock status since the behavior |
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89 | * is undefined by POSIX. But GNU/Linux returns EPERM in this |
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90 | * case, so we follow their lead. |
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91 | */ |
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92 | _Assert( mutex_error == EINVAL || mutex_error == EPERM ); |
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93 | _Thread_queue_Extract( executing ); |
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94 | _Thread_Dispatch_enable( cpu_self ); |
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95 | return EPERM; |
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96 | } |
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97 | |
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98 | /* |
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99 | * Switch ourself out because we blocked as a result of the |
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100 | * _Thread_queue_Enqueue_critical(). |
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101 | */ |
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102 | |
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103 | _Thread_Dispatch_enable( cpu_self ); |
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104 | |
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105 | error = _POSIX_Get_error_after_wait( executing ); |
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106 | |
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107 | /* |
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108 | * If the thread is interrupted, while in the thread queue, by |
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109 | * a POSIX signal, then pthread_cond_wait returns spuriously, |
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110 | * according to the POSIX standard. It means that pthread_cond_wait |
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111 | * returns a success status, except for the fact that it was not |
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112 | * woken up a pthread_cond_signal() or a pthread_cond_broadcast(). |
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113 | */ |
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114 | |
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115 | if ( error == EINTR ) { |
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116 | error = 0; |
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117 | } |
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118 | |
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119 | /* |
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120 | * When we get here the dispatch disable level is 0. |
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121 | */ |
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122 | |
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123 | mutex_error = pthread_mutex_lock( mutex ); |
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124 | if ( mutex_error != 0 ) { |
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125 | _Assert( mutex_error == EINVAL ); |
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126 | return EINVAL; |
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127 | } |
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128 | |
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129 | return error; |
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130 | } |
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