1 | /* Linuxthreads - a simple clone()-based implementation of Posix */ |
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2 | /* threads for Linux. */ |
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3 | /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */ |
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4 | /* */ |
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5 | /* This program is free software; you can redistribute it and/or */ |
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6 | /* modify it under the terms of the GNU Library General Public License */ |
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7 | /* as published by the Free Software Foundation; either version 2 */ |
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8 | /* of the License, or (at your option) any later version. */ |
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9 | /* */ |
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10 | /* This program is distributed in the hope that it will be useful, */ |
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11 | /* but WITHOUT ANY WARRANTY; without even the implied warranty of */ |
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12 | /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */ |
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13 | /* GNU Library General Public License for more details. */ |
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14 | |
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15 | /* Thread cancellation */ |
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16 | |
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17 | #include <errno.h> |
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18 | #include <rpc/rpc.h> |
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19 | #include "pthread.h" |
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20 | #include "internals.h" |
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21 | #include "spinlock.h" |
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22 | #include "restart.h" |
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23 | |
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24 | #ifdef _STACK_GROWS_DOWN |
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25 | # define FRAME_LEFT(frame, other) ((char *) frame >= (char *) other) |
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26 | #elif _STACK_GROWS_UP |
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27 | # define FRAME_LEFT(frame, other) ((char *) frame <= (char *) other) |
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28 | #else |
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29 | # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP" |
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30 | #endif |
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31 | |
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32 | |
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33 | int pthread_setcancelstate(int state, int * oldstate) |
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34 | { |
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35 | pthread_descr self = thread_self(); |
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36 | if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE) |
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37 | return EINVAL; |
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38 | if (oldstate != NULL) *oldstate = THREAD_GETMEM(self, p_cancelstate); |
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39 | THREAD_SETMEM(self, p_cancelstate, state); |
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40 | if (THREAD_GETMEM(self, p_canceled) && |
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41 | THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE && |
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42 | THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS) |
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43 | __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME); |
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44 | return 0; |
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45 | } |
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46 | |
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47 | int pthread_setcanceltype(int type, int * oldtype) |
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48 | { |
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49 | pthread_descr self = thread_self(); |
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50 | if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS) |
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51 | return EINVAL; |
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52 | if (oldtype != NULL) *oldtype = THREAD_GETMEM(self, p_canceltype); |
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53 | THREAD_SETMEM(self, p_canceltype, type); |
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54 | if (THREAD_GETMEM(self, p_canceled) && |
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55 | THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE && |
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56 | THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS) |
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57 | __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME); |
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58 | return 0; |
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59 | } |
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60 | |
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61 | int pthread_cancel(pthread_t thread) |
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62 | { |
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63 | pthread_handle handle = thread_handle(thread); |
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64 | int pid; |
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65 | int dorestart = 0; |
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66 | pthread_descr th; |
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67 | pthread_extricate_if *pextricate; |
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68 | int already_canceled; |
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69 | |
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70 | __pthread_lock(&handle->h_lock, NULL); |
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71 | if (invalid_handle(handle, thread)) { |
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72 | __pthread_unlock(&handle->h_lock); |
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73 | return ESRCH; |
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74 | } |
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75 | |
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76 | th = handle->h_descr; |
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77 | |
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78 | already_canceled = th->p_canceled; |
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79 | th->p_canceled = 1; |
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80 | |
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81 | if (th->p_cancelstate == PTHREAD_CANCEL_DISABLE || already_canceled) { |
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82 | __pthread_unlock(&handle->h_lock); |
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83 | return 0; |
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84 | } |
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85 | |
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86 | pextricate = th->p_extricate; |
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87 | pid = th->p_pid; |
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88 | |
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89 | /* If the thread has registered an extrication interface, then |
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90 | invoke the interface. If it returns 1, then we succeeded in |
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91 | dequeuing the thread from whatever waiting object it was enqueued |
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92 | with. In that case, it is our responsibility to wake it up. |
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93 | And also to set the p_woken_by_cancel flag so the woken thread |
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94 | can tell that it was woken by cancellation. */ |
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95 | |
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96 | if (pextricate != NULL) { |
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97 | dorestart = pextricate->pu_extricate_func(pextricate->pu_object, th); |
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98 | th->p_woken_by_cancel = dorestart; |
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99 | } |
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100 | |
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101 | __pthread_unlock(&handle->h_lock); |
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102 | |
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103 | /* If the thread has suspended or is about to, then we unblock it by |
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104 | issuing a restart, instead of a cancel signal. Otherwise we send |
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105 | the cancel signal to unblock the thread from a cancellation point, |
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106 | or to initiate asynchronous cancellation. The restart is needed so |
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107 | we have proper accounting of restarts; suspend decrements the thread's |
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108 | resume count, and restart() increments it. This also means that suspend's |
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109 | handling of the cancel signal is obsolete. */ |
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110 | |
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111 | if (dorestart) |
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112 | restart(th); |
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113 | else |
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114 | kill(pid, __pthread_sig_cancel); |
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115 | |
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116 | return 0; |
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117 | } |
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118 | |
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119 | void pthread_testcancel(void) |
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120 | { |
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121 | pthread_descr self = thread_self(); |
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122 | if (THREAD_GETMEM(self, p_canceled) |
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123 | && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) |
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124 | __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME); |
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125 | } |
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126 | |
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127 | void _pthread_cleanup_push(struct _pthread_cleanup_buffer * buffer, |
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128 | void (*routine)(void *), void * arg) |
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129 | { |
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130 | pthread_descr self = thread_self(); |
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131 | buffer->__routine = routine; |
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132 | buffer->__arg = arg; |
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133 | buffer->__prev = THREAD_GETMEM(self, p_cleanup); |
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134 | if (buffer->__prev != NULL && FRAME_LEFT (buffer, buffer->__prev)) |
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135 | buffer->__prev = NULL; |
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136 | THREAD_SETMEM(self, p_cleanup, buffer); |
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137 | } |
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138 | |
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139 | void _pthread_cleanup_pop(struct _pthread_cleanup_buffer * buffer, |
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140 | int execute) |
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141 | { |
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142 | pthread_descr self = thread_self(); |
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143 | if (execute) buffer->__routine(buffer->__arg); |
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144 | THREAD_SETMEM(self, p_cleanup, buffer->__prev); |
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145 | } |
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146 | |
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147 | void _pthread_cleanup_push_defer(struct _pthread_cleanup_buffer * buffer, |
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148 | void (*routine)(void *), void * arg) |
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149 | { |
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150 | pthread_descr self = thread_self(); |
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151 | buffer->__routine = routine; |
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152 | buffer->__arg = arg; |
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153 | buffer->__canceltype = THREAD_GETMEM(self, p_canceltype); |
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154 | buffer->__prev = THREAD_GETMEM(self, p_cleanup); |
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155 | if (buffer->__prev != NULL && FRAME_LEFT (buffer, buffer->__prev)) |
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156 | buffer->__prev = NULL; |
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157 | THREAD_SETMEM(self, p_canceltype, PTHREAD_CANCEL_DEFERRED); |
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158 | THREAD_SETMEM(self, p_cleanup, buffer); |
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159 | } |
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160 | |
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161 | void _pthread_cleanup_pop_restore(struct _pthread_cleanup_buffer * buffer, |
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162 | int execute) |
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163 | { |
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164 | pthread_descr self = thread_self(); |
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165 | if (execute) buffer->__routine(buffer->__arg); |
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166 | THREAD_SETMEM(self, p_cleanup, buffer->__prev); |
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167 | THREAD_SETMEM(self, p_canceltype, buffer->__canceltype); |
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168 | if (THREAD_GETMEM(self, p_canceled) && |
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169 | THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE && |
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170 | THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS) |
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171 | __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME); |
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172 | } |
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173 | |
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174 | void __pthread_perform_cleanup(char *currentframe) |
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175 | { |
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176 | pthread_descr self = thread_self(); |
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177 | struct _pthread_cleanup_buffer *c = THREAD_GETMEM(self, p_cleanup); |
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178 | struct _pthread_cleanup_buffer *last; |
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179 | |
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180 | if (c != NULL) |
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181 | while (FRAME_LEFT (currentframe, c)) |
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182 | { |
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183 | last = c; |
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184 | c = c->__prev; |
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185 | |
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186 | if (c == NULL || FRAME_LEFT (last, c)) |
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187 | { |
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188 | c = NULL; |
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189 | break; |
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190 | } |
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191 | } |
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192 | |
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193 | while (c != NULL) |
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194 | { |
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195 | c->__routine(c->__arg); |
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196 | |
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197 | last = c; |
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198 | c = c->__prev; |
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199 | |
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200 | if (FRAME_LEFT (last, c)) |
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201 | break; |
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202 | } |
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203 | |
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204 | #if 0 |
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205 | /* And the TSD which needs special help. */ |
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206 | if (THREAD_GETMEM(self, p_libc_specific[_LIBC_TSD_KEY_RPC_VARS]) != NULL) |
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207 | __rpc_thread_destroy (); |
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208 | #endif |
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209 | } |
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210 | |
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211 | #ifndef SHARED |
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212 | /* We need a hook to force the cancelation wrappers and file locking |
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213 | to be linked in when static libpthread is used. */ |
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214 | extern const int __pthread_provide_wrappers; |
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215 | static const int *const __pthread_require_wrappers = |
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216 | &__pthread_provide_wrappers; |
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217 | extern const int __pthread_provide_lockfile; |
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218 | static const int *const __pthread_require_lockfile = |
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219 | &__pthread_provide_lockfile; |
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220 | #endif |
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