root / coroutine-ucontext.c @ 6ab7e546
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1 | 00dccaf1 | Kevin Wolf | /*
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2 | 00dccaf1 | Kevin Wolf | * ucontext coroutine initialization code
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3 | 00dccaf1 | Kevin Wolf | *
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4 | 00dccaf1 | Kevin Wolf | * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
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5 | 00dccaf1 | Kevin Wolf | * Copyright (C) 2011 Kevin Wolf <kwolf@redhat.com>
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6 | 00dccaf1 | Kevin Wolf | *
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7 | 00dccaf1 | Kevin Wolf | * This library is free software; you can redistribute it and/or
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8 | 00dccaf1 | Kevin Wolf | * modify it under the terms of the GNU Lesser General Public
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9 | 00dccaf1 | Kevin Wolf | * License as published by the Free Software Foundation; either
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10 | 00dccaf1 | Kevin Wolf | * version 2.0 of the License, or (at your option) any later version.
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11 | 00dccaf1 | Kevin Wolf | *
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12 | 00dccaf1 | Kevin Wolf | * This library is distributed in the hope that it will be useful,
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13 | 00dccaf1 | Kevin Wolf | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | 00dccaf1 | Kevin Wolf | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 | 00dccaf1 | Kevin Wolf | * Lesser General Public License for more details.
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16 | 00dccaf1 | Kevin Wolf | *
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17 | 00dccaf1 | Kevin Wolf | * You should have received a copy of the GNU Lesser General Public
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18 | 00dccaf1 | Kevin Wolf | * License along with this library; if not, see <http://www.gnu.org/licenses/>.
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19 | 00dccaf1 | Kevin Wolf | */
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20 | 00dccaf1 | Kevin Wolf | |
21 | 00dccaf1 | Kevin Wolf | /* XXX Is there a nicer way to disable glibc's stack check for longjmp? */
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22 | 00dccaf1 | Kevin Wolf | #ifdef _FORTIFY_SOURCE
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23 | 00dccaf1 | Kevin Wolf | #undef _FORTIFY_SOURCE
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24 | 00dccaf1 | Kevin Wolf | #endif
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25 | 00dccaf1 | Kevin Wolf | #include <stdlib.h> |
26 | 00dccaf1 | Kevin Wolf | #include <setjmp.h> |
27 | 00dccaf1 | Kevin Wolf | #include <stdint.h> |
28 | 00dccaf1 | Kevin Wolf | #include <pthread.h> |
29 | 00dccaf1 | Kevin Wolf | #include <ucontext.h> |
30 | 00dccaf1 | Kevin Wolf | #include "qemu-common.h" |
31 | 737e150e | Paolo Bonzini | #include "block/coroutine_int.h" |
32 | 00dccaf1 | Kevin Wolf | |
33 | 3f4349dc | Kevin Wolf | #ifdef CONFIG_VALGRIND_H
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34 | 3f4349dc | Kevin Wolf | #include <valgrind/valgrind.h> |
35 | 3f4349dc | Kevin Wolf | #endif
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36 | 3f4349dc | Kevin Wolf | |
37 | 00dccaf1 | Kevin Wolf | enum {
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38 | 00dccaf1 | Kevin Wolf | /* Maximum free pool size prevents holding too many freed coroutines */
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39 | 00dccaf1 | Kevin Wolf | POOL_MAX_SIZE = 64,
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40 | 00dccaf1 | Kevin Wolf | }; |
41 | 00dccaf1 | Kevin Wolf | |
42 | 39a7a362 | Avi Kivity | /** Free list to speed up creation */
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43 | 1bbbdabd | Paolo Bonzini | static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
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44 | 39a7a362 | Avi Kivity | static unsigned int pool_size; |
45 | 39a7a362 | Avi Kivity | |
46 | 00dccaf1 | Kevin Wolf | typedef struct { |
47 | 00dccaf1 | Kevin Wolf | Coroutine base; |
48 | 00dccaf1 | Kevin Wolf | void *stack;
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49 | 6ab7e546 | Peter Maydell | sigjmp_buf env; |
50 | 3f4349dc | Kevin Wolf | |
51 | 3f4349dc | Kevin Wolf | #ifdef CONFIG_VALGRIND_H
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52 | 3f4349dc | Kevin Wolf | unsigned int valgrind_stack_id; |
53 | 3f4349dc | Kevin Wolf | #endif
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54 | 3f4349dc | Kevin Wolf | |
55 | 00dccaf1 | Kevin Wolf | } CoroutineUContext; |
56 | 00dccaf1 | Kevin Wolf | |
57 | 00dccaf1 | Kevin Wolf | /**
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58 | 00dccaf1 | Kevin Wolf | * Per-thread coroutine bookkeeping
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59 | 00dccaf1 | Kevin Wolf | */
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60 | 00dccaf1 | Kevin Wolf | typedef struct { |
61 | 00dccaf1 | Kevin Wolf | /** Currently executing coroutine */
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62 | 00dccaf1 | Kevin Wolf | Coroutine *current; |
63 | 00dccaf1 | Kevin Wolf | |
64 | 00dccaf1 | Kevin Wolf | /** The default coroutine */
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65 | 00dccaf1 | Kevin Wolf | CoroutineUContext leader; |
66 | 00dccaf1 | Kevin Wolf | } CoroutineThreadState; |
67 | 00dccaf1 | Kevin Wolf | |
68 | 00dccaf1 | Kevin Wolf | static pthread_key_t thread_state_key;
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69 | 00dccaf1 | Kevin Wolf | |
70 | 00dccaf1 | Kevin Wolf | /*
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71 | 00dccaf1 | Kevin Wolf | * va_args to makecontext() must be type 'int', so passing
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72 | 00dccaf1 | Kevin Wolf | * the pointer we need may require several int args. This
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73 | 00dccaf1 | Kevin Wolf | * union is a quick hack to let us do that
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74 | 00dccaf1 | Kevin Wolf | */
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75 | 00dccaf1 | Kevin Wolf | union cc_arg {
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76 | 00dccaf1 | Kevin Wolf | void *p;
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77 | 00dccaf1 | Kevin Wolf | int i[2]; |
78 | 00dccaf1 | Kevin Wolf | }; |
79 | 00dccaf1 | Kevin Wolf | |
80 | 00dccaf1 | Kevin Wolf | static CoroutineThreadState *coroutine_get_thread_state(void) |
81 | 00dccaf1 | Kevin Wolf | { |
82 | 00dccaf1 | Kevin Wolf | CoroutineThreadState *s = pthread_getspecific(thread_state_key); |
83 | 00dccaf1 | Kevin Wolf | |
84 | 00dccaf1 | Kevin Wolf | if (!s) {
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85 | 7267c094 | Anthony Liguori | s = g_malloc0(sizeof(*s));
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86 | 00dccaf1 | Kevin Wolf | s->current = &s->leader.base; |
87 | 00dccaf1 | Kevin Wolf | pthread_setspecific(thread_state_key, s); |
88 | 00dccaf1 | Kevin Wolf | } |
89 | 00dccaf1 | Kevin Wolf | return s;
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90 | 00dccaf1 | Kevin Wolf | } |
91 | 00dccaf1 | Kevin Wolf | |
92 | 00dccaf1 | Kevin Wolf | static void qemu_coroutine_thread_cleanup(void *opaque) |
93 | 00dccaf1 | Kevin Wolf | { |
94 | 00dccaf1 | Kevin Wolf | CoroutineThreadState *s = opaque; |
95 | 39a7a362 | Avi Kivity | |
96 | 39a7a362 | Avi Kivity | g_free(s); |
97 | 39a7a362 | Avi Kivity | } |
98 | 39a7a362 | Avi Kivity | |
99 | 39a7a362 | Avi Kivity | static void __attribute__((destructor)) coroutine_cleanup(void) |
100 | 39a7a362 | Avi Kivity | { |
101 | 00dccaf1 | Kevin Wolf | Coroutine *co; |
102 | 00dccaf1 | Kevin Wolf | Coroutine *tmp; |
103 | 00dccaf1 | Kevin Wolf | |
104 | 1bbbdabd | Paolo Bonzini | QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) { |
105 | 7267c094 | Anthony Liguori | g_free(DO_UPCAST(CoroutineUContext, base, co)->stack); |
106 | 7267c094 | Anthony Liguori | g_free(co); |
107 | 00dccaf1 | Kevin Wolf | } |
108 | 00dccaf1 | Kevin Wolf | } |
109 | 00dccaf1 | Kevin Wolf | |
110 | 00dccaf1 | Kevin Wolf | static void __attribute__((constructor)) coroutine_init(void) |
111 | 00dccaf1 | Kevin Wolf | { |
112 | 00dccaf1 | Kevin Wolf | int ret;
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113 | 00dccaf1 | Kevin Wolf | |
114 | 00dccaf1 | Kevin Wolf | ret = pthread_key_create(&thread_state_key, qemu_coroutine_thread_cleanup); |
115 | 00dccaf1 | Kevin Wolf | if (ret != 0) { |
116 | 00dccaf1 | Kevin Wolf | fprintf(stderr, "unable to create leader key: %s\n", strerror(errno));
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117 | 00dccaf1 | Kevin Wolf | abort(); |
118 | 00dccaf1 | Kevin Wolf | } |
119 | 00dccaf1 | Kevin Wolf | } |
120 | 00dccaf1 | Kevin Wolf | |
121 | 00dccaf1 | Kevin Wolf | static void coroutine_trampoline(int i0, int i1) |
122 | 00dccaf1 | Kevin Wolf | { |
123 | 00dccaf1 | Kevin Wolf | union cc_arg arg;
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124 | 00dccaf1 | Kevin Wolf | CoroutineUContext *self; |
125 | 00dccaf1 | Kevin Wolf | Coroutine *co; |
126 | 00dccaf1 | Kevin Wolf | |
127 | 00dccaf1 | Kevin Wolf | arg.i[0] = i0;
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128 | 00dccaf1 | Kevin Wolf | arg.i[1] = i1;
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129 | 00dccaf1 | Kevin Wolf | self = arg.p; |
130 | 00dccaf1 | Kevin Wolf | co = &self->base; |
131 | 00dccaf1 | Kevin Wolf | |
132 | 00dccaf1 | Kevin Wolf | /* Initialize longjmp environment and switch back the caller */
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133 | 6ab7e546 | Peter Maydell | if (!sigsetjmp(self->env, 0)) { |
134 | 6ab7e546 | Peter Maydell | siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
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135 | 00dccaf1 | Kevin Wolf | } |
136 | 00dccaf1 | Kevin Wolf | |
137 | 00dccaf1 | Kevin Wolf | while (true) { |
138 | 00dccaf1 | Kevin Wolf | co->entry(co->entry_arg); |
139 | 00dccaf1 | Kevin Wolf | qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE); |
140 | 00dccaf1 | Kevin Wolf | } |
141 | 00dccaf1 | Kevin Wolf | } |
142 | 00dccaf1 | Kevin Wolf | |
143 | 00dccaf1 | Kevin Wolf | static Coroutine *coroutine_new(void) |
144 | 00dccaf1 | Kevin Wolf | { |
145 | 00dccaf1 | Kevin Wolf | const size_t stack_size = 1 << 20; |
146 | 00dccaf1 | Kevin Wolf | CoroutineUContext *co; |
147 | 00dccaf1 | Kevin Wolf | ucontext_t old_uc, uc; |
148 | 6ab7e546 | Peter Maydell | sigjmp_buf old_env; |
149 | 32b74677 | malc | union cc_arg arg = {0}; |
150 | 00dccaf1 | Kevin Wolf | |
151 | 6ab7e546 | Peter Maydell | /* The ucontext functions preserve signal masks which incurs a
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152 | 6ab7e546 | Peter Maydell | * system call overhead. sigsetjmp(buf, 0)/siglongjmp() does not
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153 | 6ab7e546 | Peter Maydell | * preserve signal masks but only works on the current stack.
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154 | 6ab7e546 | Peter Maydell | * Since we need a way to create and switch to a new stack, use
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155 | 6ab7e546 | Peter Maydell | * the ucontext functions for that but sigsetjmp()/siglongjmp() for
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156 | 6ab7e546 | Peter Maydell | * everything else.
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157 | 00dccaf1 | Kevin Wolf | */
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158 | 00dccaf1 | Kevin Wolf | |
159 | 00dccaf1 | Kevin Wolf | if (getcontext(&uc) == -1) { |
160 | 00dccaf1 | Kevin Wolf | abort(); |
161 | 00dccaf1 | Kevin Wolf | } |
162 | 00dccaf1 | Kevin Wolf | |
163 | 7267c094 | Anthony Liguori | co = g_malloc0(sizeof(*co));
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164 | 7267c094 | Anthony Liguori | co->stack = g_malloc(stack_size); |
165 | 00dccaf1 | Kevin Wolf | co->base.entry_arg = &old_env; /* stash away our jmp_buf */
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166 | 00dccaf1 | Kevin Wolf | |
167 | 00dccaf1 | Kevin Wolf | uc.uc_link = &old_uc; |
168 | 00dccaf1 | Kevin Wolf | uc.uc_stack.ss_sp = co->stack; |
169 | 00dccaf1 | Kevin Wolf | uc.uc_stack.ss_size = stack_size; |
170 | 00dccaf1 | Kevin Wolf | uc.uc_stack.ss_flags = 0;
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171 | 00dccaf1 | Kevin Wolf | |
172 | 3f4349dc | Kevin Wolf | #ifdef CONFIG_VALGRIND_H
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173 | 3f4349dc | Kevin Wolf | co->valgrind_stack_id = |
174 | 3f4349dc | Kevin Wolf | VALGRIND_STACK_REGISTER(co->stack, co->stack + stack_size); |
175 | 3f4349dc | Kevin Wolf | #endif
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176 | 3f4349dc | Kevin Wolf | |
177 | 00dccaf1 | Kevin Wolf | arg.p = co; |
178 | 00dccaf1 | Kevin Wolf | |
179 | 00dccaf1 | Kevin Wolf | makecontext(&uc, (void (*)(void))coroutine_trampoline, |
180 | 00dccaf1 | Kevin Wolf | 2, arg.i[0], arg.i[1]); |
181 | 00dccaf1 | Kevin Wolf | |
182 | 6ab7e546 | Peter Maydell | /* swapcontext() in, siglongjmp() back out */
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183 | 6ab7e546 | Peter Maydell | if (!sigsetjmp(old_env, 0)) { |
184 | 00dccaf1 | Kevin Wolf | swapcontext(&old_uc, &uc); |
185 | 00dccaf1 | Kevin Wolf | } |
186 | 00dccaf1 | Kevin Wolf | return &co->base;
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187 | 00dccaf1 | Kevin Wolf | } |
188 | 00dccaf1 | Kevin Wolf | |
189 | 00dccaf1 | Kevin Wolf | Coroutine *qemu_coroutine_new(void)
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190 | 00dccaf1 | Kevin Wolf | { |
191 | 00dccaf1 | Kevin Wolf | Coroutine *co; |
192 | 00dccaf1 | Kevin Wolf | |
193 | 1bbbdabd | Paolo Bonzini | co = QSLIST_FIRST(&pool); |
194 | 00dccaf1 | Kevin Wolf | if (co) {
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195 | 1bbbdabd | Paolo Bonzini | QSLIST_REMOVE_HEAD(&pool, pool_next); |
196 | 39a7a362 | Avi Kivity | pool_size--; |
197 | 00dccaf1 | Kevin Wolf | } else {
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198 | 00dccaf1 | Kevin Wolf | co = coroutine_new(); |
199 | 00dccaf1 | Kevin Wolf | } |
200 | 00dccaf1 | Kevin Wolf | return co;
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201 | 00dccaf1 | Kevin Wolf | } |
202 | 00dccaf1 | Kevin Wolf | |
203 | 3f4349dc | Kevin Wolf | #ifdef CONFIG_VALGRIND_H
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204 | cc6e3ca9 | Gerd Hoffmann | #ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
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205 | 3f4349dc | Kevin Wolf | /* Work around an unused variable in the valgrind.h macro... */
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206 | 3f4349dc | Kevin Wolf | #pragma GCC diagnostic ignored "-Wunused-but-set-variable" |
207 | 06d71fa1 | Peter Maydell | #endif
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208 | 3f4349dc | Kevin Wolf | static inline void valgrind_stack_deregister(CoroutineUContext *co) |
209 | 3f4349dc | Kevin Wolf | { |
210 | 3f4349dc | Kevin Wolf | VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id); |
211 | 3f4349dc | Kevin Wolf | } |
212 | cc6e3ca9 | Gerd Hoffmann | #ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
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213 | 3f4349dc | Kevin Wolf | #pragma GCC diagnostic error "-Wunused-but-set-variable" |
214 | 3f4349dc | Kevin Wolf | #endif
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215 | 06d71fa1 | Peter Maydell | #endif
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216 | 3f4349dc | Kevin Wolf | |
217 | 00dccaf1 | Kevin Wolf | void qemu_coroutine_delete(Coroutine *co_)
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218 | 00dccaf1 | Kevin Wolf | { |
219 | 00dccaf1 | Kevin Wolf | CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_); |
220 | 00dccaf1 | Kevin Wolf | |
221 | 39a7a362 | Avi Kivity | if (pool_size < POOL_MAX_SIZE) {
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222 | 1bbbdabd | Paolo Bonzini | QSLIST_INSERT_HEAD(&pool, &co->base, pool_next); |
223 | 00dccaf1 | Kevin Wolf | co->base.caller = NULL;
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224 | 39a7a362 | Avi Kivity | pool_size++; |
225 | 00dccaf1 | Kevin Wolf | return;
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226 | 00dccaf1 | Kevin Wolf | } |
227 | 00dccaf1 | Kevin Wolf | |
228 | 3f4349dc | Kevin Wolf | #ifdef CONFIG_VALGRIND_H
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229 | 3f4349dc | Kevin Wolf | valgrind_stack_deregister(co); |
230 | 3f4349dc | Kevin Wolf | #endif
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231 | 3f4349dc | Kevin Wolf | |
232 | 7267c094 | Anthony Liguori | g_free(co->stack); |
233 | 7267c094 | Anthony Liguori | g_free(co); |
234 | 00dccaf1 | Kevin Wolf | } |
235 | 00dccaf1 | Kevin Wolf | |
236 | 00dccaf1 | Kevin Wolf | CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_, |
237 | 00dccaf1 | Kevin Wolf | CoroutineAction action) |
238 | 00dccaf1 | Kevin Wolf | { |
239 | 00dccaf1 | Kevin Wolf | CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_); |
240 | 00dccaf1 | Kevin Wolf | CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_); |
241 | 00dccaf1 | Kevin Wolf | CoroutineThreadState *s = coroutine_get_thread_state(); |
242 | 00dccaf1 | Kevin Wolf | int ret;
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243 | 00dccaf1 | Kevin Wolf | |
244 | 00dccaf1 | Kevin Wolf | s->current = to_; |
245 | 00dccaf1 | Kevin Wolf | |
246 | 6ab7e546 | Peter Maydell | ret = sigsetjmp(from->env, 0);
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247 | 00dccaf1 | Kevin Wolf | if (ret == 0) { |
248 | 6ab7e546 | Peter Maydell | siglongjmp(to->env, action); |
249 | 00dccaf1 | Kevin Wolf | } |
250 | 00dccaf1 | Kevin Wolf | return ret;
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251 | 00dccaf1 | Kevin Wolf | } |
252 | 00dccaf1 | Kevin Wolf | |
253 | 00dccaf1 | Kevin Wolf | Coroutine *qemu_coroutine_self(void)
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254 | 00dccaf1 | Kevin Wolf | { |
255 | 00dccaf1 | Kevin Wolf | CoroutineThreadState *s = coroutine_get_thread_state(); |
256 | 00dccaf1 | Kevin Wolf | |
257 | 00dccaf1 | Kevin Wolf | return s->current;
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258 | 00dccaf1 | Kevin Wolf | } |
259 | 00dccaf1 | Kevin Wolf | |
260 | 00dccaf1 | Kevin Wolf | bool qemu_in_coroutine(void) |
261 | 00dccaf1 | Kevin Wolf | { |
262 | 00dccaf1 | Kevin Wolf | CoroutineThreadState *s = pthread_getspecific(thread_state_key); |
263 | 00dccaf1 | Kevin Wolf | |
264 | 00dccaf1 | Kevin Wolf | return s && s->current->caller;
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265 | 00dccaf1 | Kevin Wolf | } |