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1 | jermar | 1 | /* |
2071 | jermar | 2 | * Copyright (c) 2001-2004 Jakub Jermar |
1 | jermar | 3 | * All rights reserved. |
4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
1757 | jermar | 29 | /** @addtogroup sync |
1702 | cejka | 30 | * @{ |
31 | */ |
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32 | |||
1264 | jermar | 33 | /** |
1702 | cejka | 34 | * @file |
1264 | jermar | 35 | * @brief Spinlocks. |
36 | */ |
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37 | |||
383 | jermar | 38 | #include <synch/spinlock.h> |
1104 | jermar | 39 | #include <atomic.h> |
153 | jermar | 40 | #include <arch/barrier.h> |
383 | jermar | 41 | #include <arch.h> |
223 | jermar | 42 | #include <preemption.h> |
195 | vana | 43 | #include <print.h> |
383 | jermar | 44 | #include <debug.h> |
552 | palkovsky | 45 | #include <symtab.h> |
1 | jermar | 46 | |
1313 | jermar | 47 | #ifdef CONFIG_FB |
48 | #include <genarch/fb/fb.h> |
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49 | #endif |
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50 | |||
458 | decky | 51 | #ifdef CONFIG_SMP |
1 | jermar | 52 | |
383 | jermar | 53 | /** Initialize spinlock |
54 | * |
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55 | * Initialize spinlock. |
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56 | * |
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57 | * @param sl Pointer to spinlock_t structure. |
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58 | */ |
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552 | palkovsky | 59 | void spinlock_initialize(spinlock_t *sl, char *name) |
1 | jermar | 60 | { |
625 | palkovsky | 61 | atomic_set(&sl->val, 0); |
552 | palkovsky | 62 | #ifdef CONFIG_DEBUG_SPINLOCK |
63 | sl->name = name; |
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64 | #endif |
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1 | jermar | 65 | } |
66 | |||
383 | jermar | 67 | /** Lock spinlock |
68 | * |
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69 | * Lock spinlock. |
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70 | * This version has limitted ability to report |
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71 | * possible occurence of deadlock. |
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72 | * |
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73 | * @param sl Pointer to spinlock_t structure. |
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74 | */ |
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1100 | palkovsky | 75 | #ifdef CONFIG_DEBUG_SPINLOCK |
76 | void spinlock_lock_debug(spinlock_t *sl) |
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1 | jermar | 77 | { |
557 | jermar | 78 | count_t i = 0; |
552 | palkovsky | 79 | char *symbol; |
557 | jermar | 80 | bool deadlock_reported = false; |
1 | jermar | 81 | |
223 | jermar | 82 | preemption_disable(); |
1 | jermar | 83 | while (test_and_set(&sl->val)) { |
1313 | jermar | 84 | |
85 | /* |
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2211 | decky | 86 | * We need to be careful about printf_lock and fb_lock. |
1313 | jermar | 87 | * Both of them are used to report deadlocks via |
88 | * printf() and fb_putchar(). |
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89 | * |
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90 | * We trust our code that there is no possible deadlock |
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91 | * caused by these two locks (except when an exception |
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92 | * is triggered for instance by printf() or fb_putchar()). |
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93 | * However, we encountered false positives caused by very |
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94 | * slow VESA framebuffer interaction (especially when |
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95 | * run in a simulator) that caused problems with both |
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2211 | decky | 96 | * printf_lock and fb_lock. |
1313 | jermar | 97 | * |
2211 | decky | 98 | * Possible deadlocks on both printf_lock and fb_lock |
1313 | jermar | 99 | * are therefore not reported as they would cause an |
100 | * infinite recursion. |
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101 | */ |
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2211 | decky | 102 | if (sl == &printf_lock) |
1313 | jermar | 103 | continue; |
104 | #ifdef CONFIG_FB |
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105 | if (sl == &fb_lock) |
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106 | continue; |
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107 | #endif |
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1667 | jermar | 108 | if (i++ > DEADLOCK_THRESHOLD) { |
3059 | decky | 109 | printf("cpu%u: looping on spinlock %" PRIp ":%s, caller=%" PRIp, |
110 | CPU->id, sl, sl->name, CALLER); |
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622 | palkovsky | 111 | symbol = get_symtab_entry(CALLER); |
552 | palkovsky | 112 | if (symbol) |
113 | printf("(%s)", symbol); |
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114 | printf("\n"); |
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1 | jermar | 115 | i = 0; |
557 | jermar | 116 | deadlock_reported = true; |
1 | jermar | 117 | } |
118 | } |
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383 | jermar | 119 | |
557 | jermar | 120 | if (deadlock_reported) |
3059 | decky | 121 | printf("cpu%u: not deadlocked\n", CPU->id); |
557 | jermar | 122 | |
383 | jermar | 123 | /* |
124 | * Prevent critical section code from bleeding out this way up. |
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125 | */ |
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153 | jermar | 126 | CS_ENTER_BARRIER(); |
1 | jermar | 127 | } |
128 | #endif |
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129 | |||
383 | jermar | 130 | /** Lock spinlock conditionally |
131 | * |
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132 | * Lock spinlock conditionally. |
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133 | * If the spinlock is not available at the moment, |
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134 | * signal failure. |
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135 | * |
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136 | * @param sl Pointer to spinlock_t structure. |
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137 | * |
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138 | * @return Zero on failure, non-zero otherwise. |
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139 | */ |
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1 | jermar | 140 | int spinlock_trylock(spinlock_t *sl) |
141 | { |
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153 | jermar | 142 | int rc; |
143 | |||
223 | jermar | 144 | preemption_disable(); |
153 | jermar | 145 | rc = !test_and_set(&sl->val); |
383 | jermar | 146 | |
147 | /* |
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148 | * Prevent critical section code from bleeding out this way up. |
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149 | */ |
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153 | jermar | 150 | CS_ENTER_BARRIER(); |
223 | jermar | 151 | |
152 | if (!rc) |
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153 | preemption_enable(); |
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153 | jermar | 154 | |
155 | return rc; |
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1 | jermar | 156 | } |
157 | |||
158 | #endif |
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1702 | cejka | 159 | |
1757 | jermar | 160 | /** @} |
1702 | cejka | 161 | */ |