1 | /* |
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2 | * Thread Dispatch Disable Level Methods |
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3 | * |
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4 | * COPYRIGHT (c) 1989-2011. |
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5 | * On-Line Applications Research Corporation (OAR). |
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6 | * |
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7 | * The license and distribution terms for this file may be |
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8 | * found in the file LICENSE in this distribution or at |
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9 | * http://www.rtems.com/license/LICENSE. |
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10 | */ |
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11 | |
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12 | #include <rtems/system.h> |
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13 | #include <rtems/score/apiext.h> |
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14 | #include <rtems/score/context.h> |
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15 | #include <rtems/score/interr.h> |
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16 | #include <rtems/score/isr.h> |
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17 | #include <rtems/score/object.h> |
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18 | #include <rtems/score/priority.h> |
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19 | #include <rtems/score/states.h> |
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20 | #include <rtems/score/sysstate.h> |
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21 | #include <rtems/score/thread.h> |
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22 | |
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23 | void _Thread_Dispatch_initialization( void ) |
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24 | { |
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25 | _Thread_Dispatch_disable_level = 0; |
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26 | _SMP_lock_spinlock_nested_Initialize(&_Thread_Dispatch_disable_level_lock); |
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27 | _Thread_Dispatch_set_disable_level( 1 ); |
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28 | } |
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29 | |
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30 | bool _Thread_Dispatch_in_critical_section(void) |
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31 | { |
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32 | if ( _Thread_Dispatch_disable_level == 0 ) |
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33 | return false; |
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34 | |
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35 | return true; |
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36 | } |
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37 | |
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38 | uint32_t _Thread_Dispatch_get_disable_level(void) |
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39 | { |
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40 | return _Thread_Dispatch_disable_level; |
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41 | } |
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42 | |
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43 | uint32_t _Thread_Dispatch_increment_disable_level(void) |
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44 | { |
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45 | ISR_Level isr_level; |
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46 | uint32_t level; |
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47 | |
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48 | /* |
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49 | * Note: _SMP_lock_spinlock_nested_Obtain returns |
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50 | * with ISR's disabled and the isr_level that |
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51 | * should be restored after a short period. |
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52 | * |
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53 | * Here we obtain the lock and increment the |
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54 | * Thread dispatch disable level while under the |
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55 | * protection of the isr being off. After this |
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56 | * point it is safe to re-enable ISRs and allow |
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57 | * the dispatch disable lock to provide protection. |
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58 | */ |
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59 | |
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60 | isr_level = _SMP_lock_spinlock_nested_Obtain( |
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61 | &_Thread_Dispatch_disable_level_lock |
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62 | ); |
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63 | |
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64 | _Thread_Dispatch_disable_level++; |
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65 | level = _Thread_Dispatch_disable_level; |
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66 | |
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67 | _ISR_Enable_on_this_core(isr_level); |
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68 | return level; |
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69 | } |
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70 | |
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71 | uint32_t _Thread_Dispatch_decrement_disable_level(void) |
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72 | { |
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73 | ISR_Level isr_level; |
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74 | uint32_t level; |
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75 | |
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76 | /* First we must disable ISRs in order to protect |
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77 | * accesses to the dispatch disable level. |
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78 | */ |
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79 | _ISR_Disable_on_this_core( isr_level ); |
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80 | |
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81 | _Thread_Dispatch_disable_level--; |
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82 | level = _Thread_Dispatch_disable_level; |
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83 | |
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84 | |
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85 | /* |
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86 | * Note: _SMP_lock_spinlock_nested_Obtain returns with |
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87 | * ISR's disabled and _SMP_lock_spinlock_nested_Release |
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88 | * is responsable for re-enabling interrupts. |
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89 | */ |
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90 | _SMP_lock_spinlock_nested_Release( |
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91 | &_Thread_Dispatch_disable_level_lock, |
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92 | isr_level |
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93 | ); |
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94 | |
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95 | return level; |
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96 | } |
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97 | |
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98 | |
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99 | /* |
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100 | * Note this method is taking a heavy handed approach to |
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101 | * setting the dispatch level. This may be optimized at a |
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102 | * later timee, but it must be in such a way that the nesting |
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103 | * level is decremented by the same number as the dispatch level. |
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104 | * This approach is safest until we are sure the nested spinlock |
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105 | * is successfully working with smp isr source code. |
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106 | */ |
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107 | |
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108 | uint32_t _Thread_Dispatch_set_disable_level(uint32_t value) |
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109 | { |
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110 | /* |
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111 | * If we need the dispatch level to go higher |
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112 | * call increment method the desired number of times. |
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113 | */ |
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114 | |
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115 | while ( value > _Thread_Dispatch_disable_level ) { |
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116 | _Thread_Dispatch_increment_disable_level(); |
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117 | } |
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118 | |
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119 | /* |
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120 | * If we need the dispatch level to go lower |
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121 | * call increment method the desired number of times. |
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122 | */ |
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123 | |
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124 | while ( value < _Thread_Dispatch_disable_level ) { |
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125 | _Thread_Dispatch_decrement_disable_level(); |
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126 | } |
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127 | |
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128 | return value; |
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129 | } |
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