1 | /* |
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2 | * spinlock.c - kernel spinlock synchronization |
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3 | * |
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4 | * Authors Ghassan Almaless (2008,2009,2010,2011,2012) |
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5 | * Alain Greiner (2016} |
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6 | * |
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7 | * Copyright (c) UPMC Sorbonne Universites |
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8 | * |
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9 | * This file is part of ALMOS-MKH. |
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10 | * |
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11 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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12 | * under the terms of the GNU General Public License as published by |
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13 | * the Free Software Foundation; version 2.0 of the License. |
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14 | * |
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15 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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16 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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18 | * General Public License for more details. |
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19 | * |
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20 | * You should have received a copy of the GNU General Public License |
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21 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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22 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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23 | */ |
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24 | |
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25 | #include <kernel_config.h> |
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26 | #include <hal_kernel_types.h> |
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27 | #include <hal_atomic.h> |
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28 | #include <hal_special.h> |
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29 | #include <hal_irqmask.h> |
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30 | #include <thread.h> |
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31 | #include <scheduler.h> |
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32 | #include <printk.h> |
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33 | #include <spinlock.h> |
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34 | |
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35 | ////////////////////////////////////////////// |
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36 | inline void spinlock_init( spinlock_t * lock ) |
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37 | { |
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38 | lock->taken = 0; |
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39 | |
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40 | #if DEBUG_SPINLOCKS |
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41 | lock->owner = NULL; |
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42 | list_entry_init( &lock->list ); |
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43 | #endif |
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44 | |
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45 | } |
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46 | |
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47 | /////////////////////////////////////////// |
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48 | void spinlock_lock_busy( spinlock_t * lock, |
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49 | uint32_t * irq_state ) |
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50 | { |
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51 | reg_t mode; |
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52 | volatile uint32_t taken; |
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53 | thread_t * this = CURRENT_THREAD; |
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54 | bool_t isAtomic = false; |
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55 | |
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56 | // disable interrupts |
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57 | hal_disable_irq( &mode ); |
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58 | |
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59 | // loop until success |
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60 | while( isAtomic == false ) |
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61 | { |
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62 | taken = lock->taken; |
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63 | |
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64 | // try to take the lock if not already taken |
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65 | if( taken == 0 ) |
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66 | { |
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67 | isAtomic = hal_atomic_cas( &lock->taken , 0 , 1 ); |
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68 | } |
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69 | } |
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70 | |
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71 | this->local_locks++; |
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72 | |
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73 | #if DEBUG_SPINLOCKS |
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74 | lock->owner = this; |
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75 | list_add_first( &this->locks_root , &lock->list ); |
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76 | #endif |
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77 | |
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78 | // irq_state must be restored when lock is released |
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79 | *irq_state = mode; |
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80 | } |
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81 | |
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82 | ////////////////////////////////////////////// |
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83 | void spinlock_unlock_busy( spinlock_t * lock, |
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84 | uint32_t irq_state ) |
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85 | { |
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86 | thread_t * this = CURRENT_THREAD;; |
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87 | |
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88 | #if DEBUG_SPINLOCKS |
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89 | lock->owner = NULL; |
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90 | list_unlink( &lock->list ); |
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91 | #endif |
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92 | |
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93 | lock->taken = 0; |
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94 | this->local_locks--; |
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95 | |
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96 | // deschedule if pending request |
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97 | thread_check_sched(); |
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98 | |
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99 | // restore IRQs |
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100 | hal_restore_irq( irq_state ); |
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101 | } |
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102 | |
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103 | /////////////////////////////////////// |
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104 | void spinlock_lock( spinlock_t * lock ) |
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105 | { |
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106 | reg_t mode; |
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107 | thread_t * this = CURRENT_THREAD; |
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108 | bool_t isAtomic = false; |
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109 | volatile uint32_t taken; |
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110 | |
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111 | // disable interrupts |
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112 | hal_disable_irq( &mode ); |
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113 | |
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114 | // loop until success |
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115 | while( isAtomic == false ) |
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116 | { |
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117 | taken = lock->taken; |
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118 | |
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119 | // deschedule without blocking when lock already taken |
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120 | if( taken != 0 ) |
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121 | { |
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122 | hal_restore_irq( mode ); |
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123 | if( thread_can_yield() ) sched_yield("waiting spinlock"); |
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124 | hal_disable_irq( &mode ); |
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125 | continue; |
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126 | } |
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127 | |
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128 | // try to atomically take the lock if not already taken |
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129 | isAtomic = hal_atomic_cas( &lock->taken , 0 , 1 ); |
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130 | } |
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131 | |
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132 | this->local_locks++; |
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133 | |
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134 | #if DEBUG_SPINLOCKS |
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135 | lock->owner = this; |
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136 | list_add_first( &this->locks_root , &lock->list ); |
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137 | #endif |
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138 | |
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139 | // restore IRQs |
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140 | hal_restore_irq( mode ); |
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141 | } |
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142 | |
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143 | ///////////////////////////////////////////// |
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144 | error_t spinlock_trylock( spinlock_t * lock ) |
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145 | { |
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146 | reg_t mode; |
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147 | bool_t isAtomic = false; |
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148 | thread_t * this = CURRENT_THREAD; |
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149 | |
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150 | hal_disable_irq( &mode ); |
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151 | |
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152 | if( lock->taken == 0) |
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153 | isAtomic = hal_atomic_cas( &lock->taken , 0 , 1); |
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154 | |
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155 | if(isAtomic == false) |
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156 | { |
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157 | hal_restore_irq(mode); |
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158 | return 1; |
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159 | } |
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160 | else |
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161 | { |
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162 | this->local_locks++; |
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163 | |
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164 | #if DEBUG_SPINLOCKS |
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165 | lock->owner = this; |
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166 | list_add_first( &this->locks_root , &lock->list ); |
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167 | #endif |
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168 | |
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169 | hal_restore_irq(mode); |
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170 | return 0; |
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171 | } |
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172 | } |
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173 | |
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174 | ///////////////////////////////////////// |
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175 | void spinlock_unlock( spinlock_t * lock ) |
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176 | { |
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177 | thread_t * this = CURRENT_THREAD; |
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178 | |
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179 | #if DEBUG_SPINLOCKS |
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180 | lock->owner = NULL; |
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181 | list_unlink( &lock->list ); |
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182 | #endif |
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183 | |
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184 | lock->taken = 0; |
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185 | this->local_locks--; |
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186 | |
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187 | // deschedule if pending request |
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188 | thread_check_sched(); |
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189 | } |
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190 | |
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