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67337c4a MD |
1 | // SPDX-License-Identifier: MIT |
2 | /* | |
3 | * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | */ | |
5 | ||
6 | #include <side/trace.h> | |
7 | #include <string.h> | |
b1bf768c | 8 | #include <assert.h> |
a125f217 MD |
9 | #include <pthread.h> |
10 | #include <unistd.h> | |
7e38dc2e | 11 | #include <poll.h> |
67337c4a | 12 | |
7e38dc2e | 13 | #include "compiler.h" |
67337c4a MD |
14 | #include "rcu.h" |
15 | #include "list.h" | |
873bbf16 | 16 | #include "rculist.h" |
67337c4a | 17 | |
871851e7 | 18 | /* Top 8 bits reserved for shared tracer use. */ |
67337c4a | 19 | #if SIDE_BITS_PER_LONG == 64 |
871851e7 MD |
20 | # define SIDE_EVENT_ENABLED_SHARED_MASK 0xFF00000000000000ULL |
21 | # define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK 0x8000000000000000ULL | |
22 | # define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK 0x4000000000000000ULL | |
67337c4a | 23 | |
871851e7 MD |
24 | /* Allow 2^56 private tracer references on an event. */ |
25 | # define SIDE_EVENT_ENABLED_PRIVATE_MASK 0x00FFFFFFFFFFFFFFULL | |
67337c4a | 26 | #else |
871851e7 MD |
27 | # define SIDE_EVENT_ENABLED_SHARED_MASK 0xFF000000UL |
28 | # define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK 0x80000000UL | |
29 | # define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK 0x40000000UL | |
67337c4a | 30 | |
871851e7 MD |
31 | /* Allow 2^24 private tracer references on an event. */ |
32 | # define SIDE_EVENT_ENABLED_PRIVATE_MASK 0x00FFFFFFUL | |
67337c4a MD |
33 | #endif |
34 | ||
bffe9ae3 MD |
35 | #define SIDE_KEY_RESERVED_RANGE_END 0x8 |
36 | ||
37 | /* Key 0x0 is reserved to match all. */ | |
38 | #define SIDE_KEY_MATCH_ALL 0x0 | |
871851e7 | 39 | /* Key 0x1 is reserved for user event. */ |
bffe9ae3 | 40 | #define SIDE_KEY_USER_EVENT 0x1 |
871851e7 | 41 | /* Key 0x2 is reserved for ptrace. */ |
bffe9ae3 | 42 | #define SIDE_KEY_PTRACE 0x2 |
871851e7 | 43 | |
7e38dc2e MD |
44 | #define SIDE_RETRY_BUSY_LOOP_ATTEMPTS 100 |
45 | #define SIDE_RETRY_DELAY_MS 1 | |
46 | ||
67337c4a MD |
47 | struct side_events_register_handle { |
48 | struct side_list_node node; | |
49 | struct side_event_description **events; | |
50 | uint32_t nr_events; | |
51 | }; | |
52 | ||
53 | struct side_tracer_handle { | |
54 | struct side_list_node node; | |
55 | void (*cb)(enum side_tracer_notification notif, | |
56 | struct side_event_description **events, uint32_t nr_events, void *priv); | |
57 | void *priv; | |
58 | }; | |
59 | ||
bffe9ae3 MD |
60 | struct side_statedump_notification { |
61 | struct side_list_node node; | |
62 | uint64_t key; | |
63 | }; | |
64 | ||
f0b01832 | 65 | struct side_statedump_request_handle { |
bffe9ae3 MD |
66 | struct side_list_node node; /* Statedump request RCU list node. */ |
67 | struct side_list_head notification_queue; /* Queue of struct side_statedump_notification */ | |
3da13b2c | 68 | void (*cb)(void *statedump_request_key); |
bffe9ae3 MD |
69 | char *name; |
70 | enum side_statedump_mode mode; | |
f0b01832 MD |
71 | }; |
72 | ||
867b4725 MD |
73 | struct side_callback { |
74 | union { | |
75 | void (*call)(const struct side_event_description *desc, | |
76 | const struct side_arg_vec *side_arg_vec, | |
77 | void *priv); | |
78 | void (*call_variadic)(const struct side_event_description *desc, | |
79 | const struct side_arg_vec *side_arg_vec, | |
80 | const struct side_arg_dynamic_struct *var_struct, | |
81 | void *priv); | |
82 | } u; | |
83 | void *priv; | |
bffe9ae3 | 84 | uint64_t key; |
867b4725 MD |
85 | }; |
86 | ||
a125f217 MD |
87 | enum agent_thread_state { |
88 | AGENT_THREAD_STATE_BLOCKED = 0, | |
89 | AGENT_THREAD_STATE_HANDLE_REQUEST = (1 << 0), | |
90 | AGENT_THREAD_STATE_EXIT = (1 << 1), | |
7e38dc2e MD |
91 | AGENT_THREAD_STATE_PAUSE = (1 << 2), |
92 | AGENT_THREAD_STATE_PAUSE_ACK = (1 << 3), | |
a125f217 MD |
93 | }; |
94 | ||
95 | struct statedump_agent_thread { | |
96 | long ref; | |
97 | pthread_t id; | |
98 | enum agent_thread_state state; | |
76dd11f9 MD |
99 | pthread_cond_t worker_cond; |
100 | pthread_cond_t waiter_cond; | |
a125f217 MD |
101 | }; |
102 | ||
873bbf16 | 103 | static struct side_rcu_gp_state event_rcu_gp, statedump_rcu_gp; |
67337c4a MD |
104 | |
105 | /* | |
106 | * Lazy initialization for early use within library constructors. | |
107 | */ | |
108 | static bool initialized; | |
109 | /* | |
110 | * Do not register/unregister any more events after destructor. | |
111 | */ | |
112 | static bool finalized; | |
113 | ||
114 | /* | |
115 | * Recursive mutex to allow tracer callbacks to use the side API. | |
116 | */ | |
873bbf16 MD |
117 | static pthread_mutex_t side_event_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; |
118 | static pthread_mutex_t side_statedump_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; | |
bffe9ae3 | 119 | static pthread_mutex_t side_key_lock = PTHREAD_MUTEX_INITIALIZER; |
76dd11f9 MD |
120 | /* |
121 | * The side_agent_thread_lock protects the life-time of the agent | |
122 | * thread: reference counting, creation, join. It is not taken by | |
123 | * the agent thread per se so it does not have a circular dependency | |
124 | * with pthread join. | |
125 | * The side_statedump_lock nests inside the side_agent_thread_lock. | |
126 | */ | |
127 | static pthread_mutex_t side_agent_thread_lock = PTHREAD_MUTEX_INITIALIZER; | |
bffe9ae3 MD |
128 | |
129 | /* Dynamic tracer key allocation. */ | |
130 | static uint64_t side_key_next = SIDE_KEY_RESERVED_RANGE_END; | |
67337c4a | 131 | |
a125f217 MD |
132 | static struct statedump_agent_thread statedump_agent_thread; |
133 | ||
67337c4a MD |
134 | static DEFINE_SIDE_LIST_HEAD(side_events_list); |
135 | static DEFINE_SIDE_LIST_HEAD(side_tracer_list); | |
bffe9ae3 MD |
136 | |
137 | /* | |
138 | * The statedump request list is a RCU list to allow the agent thread to | |
139 | * iterate over this list with a RCU read-side lock. | |
140 | */ | |
f0b01832 | 141 | static DEFINE_SIDE_LIST_HEAD(side_statedump_list); |
67337c4a MD |
142 | |
143 | /* | |
144 | * The empty callback has a NULL function callback pointer, which stops | |
145 | * iteration on the array of callbacks immediately. | |
146 | */ | |
867b4725 | 147 | const char side_empty_callback[sizeof(struct side_callback)]; |
67337c4a | 148 | |
bffe9ae3 MD |
149 | side_static_event(side_statedump_begin, "side", "statedump_begin", |
150 | SIDE_LOGLEVEL_INFO, side_field_list(side_field_string("name"))); | |
151 | side_static_event(side_statedump_end, "side", "statedump_end", | |
152 | SIDE_LOGLEVEL_INFO, side_field_list(side_field_string("name"))); | |
153 | ||
871851e7 MD |
154 | /* |
155 | * side_ptrace_hook is a place holder for a debugger breakpoint. | |
156 | * var_struct is NULL if not variadic. | |
157 | */ | |
158 | void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)), | |
e7f33720 MD |
159 | const struct side_arg_vec *side_arg_vec __attribute__((unused)), |
160 | const struct side_arg_dynamic_struct *var_struct __attribute__((unused))) | |
161 | __attribute__((noinline)); | |
871851e7 | 162 | void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)), |
e7f33720 MD |
163 | const struct side_arg_vec *side_arg_vec __attribute__((unused)), |
164 | const struct side_arg_dynamic_struct *var_struct __attribute__((unused))) | |
871851e7 MD |
165 | { |
166 | } | |
167 | ||
74be90b7 | 168 | static |
bffe9ae3 | 169 | void _side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec, uint64_t key) |
67337c4a MD |
170 | { |
171 | struct side_rcu_read_state rcu_read_state; | |
b2a84b9f | 172 | const struct side_event_state_0 *es0; |
67337c4a MD |
173 | const struct side_callback *side_cb; |
174 | uintptr_t enabled; | |
175 | ||
176 | if (side_unlikely(finalized)) | |
177 | return; | |
178 | if (side_unlikely(!initialized)) | |
179 | side_init(); | |
b2a84b9f MD |
180 | if (side_unlikely(event_state->version != 0)) |
181 | abort(); | |
49aea3ef | 182 | es0 = side_container_of(event_state, const struct side_event_state_0, parent); |
7269a8a3 | 183 | assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC)); |
b2a84b9f | 184 | enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED); |
871851e7 MD |
185 | if (side_unlikely(enabled & SIDE_EVENT_ENABLED_SHARED_MASK)) { |
186 | if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) && | |
bffe9ae3 | 187 | (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_USER_EVENT)) { |
871851e7 MD |
188 | // TODO: call kernel write. |
189 | } | |
190 | if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) && | |
bffe9ae3 | 191 | (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_PTRACE)) |
871851e7 | 192 | side_ptrace_hook(event_state, side_arg_vec, NULL); |
67337c4a | 193 | } |
873bbf16 | 194 | side_rcu_read_begin(&event_rcu_gp, &rcu_read_state); |
92c377f9 | 195 | for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) { |
bffe9ae3 | 196 | if (key != SIDE_KEY_MATCH_ALL && side_cb->key != SIDE_KEY_MATCH_ALL && side_cb->key != key) |
92c377f9 | 197 | continue; |
7269a8a3 | 198 | side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv); |
92c377f9 | 199 | } |
873bbf16 | 200 | side_rcu_read_end(&event_rcu_gp, &rcu_read_state); |
67337c4a MD |
201 | } |
202 | ||
92c377f9 MD |
203 | void side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec) |
204 | { | |
bffe9ae3 | 205 | _side_call(event_state, side_arg_vec, SIDE_KEY_MATCH_ALL); |
92c377f9 MD |
206 | } |
207 | ||
3da13b2c MD |
208 | void side_statedump_call(const struct side_event_state *event_state, |
209 | const struct side_arg_vec *side_arg_vec, | |
210 | void *statedump_request_key) | |
74be90b7 | 211 | { |
3da13b2c | 212 | _side_call(event_state, side_arg_vec, *(const uint64_t *) statedump_request_key); |
74be90b7 MD |
213 | } |
214 | ||
215 | static | |
216 | void _side_call_variadic(const struct side_event_state *event_state, | |
e7f33720 MD |
217 | const struct side_arg_vec *side_arg_vec, |
218 | const struct side_arg_dynamic_struct *var_struct, | |
219 | uint64_t key) | |
67337c4a MD |
220 | { |
221 | struct side_rcu_read_state rcu_read_state; | |
b2a84b9f | 222 | const struct side_event_state_0 *es0; |
67337c4a MD |
223 | const struct side_callback *side_cb; |
224 | uintptr_t enabled; | |
225 | ||
226 | if (side_unlikely(finalized)) | |
227 | return; | |
228 | if (side_unlikely(!initialized)) | |
229 | side_init(); | |
b2a84b9f MD |
230 | if (side_unlikely(event_state->version != 0)) |
231 | abort(); | |
49aea3ef | 232 | es0 = side_container_of(event_state, const struct side_event_state_0, parent); |
7269a8a3 | 233 | assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC); |
b2a84b9f | 234 | enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED); |
871851e7 MD |
235 | if (side_unlikely(enabled & SIDE_EVENT_ENABLED_SHARED_MASK)) { |
236 | if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) && | |
bffe9ae3 | 237 | (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_USER_EVENT)) { |
871851e7 MD |
238 | // TODO: call kernel write. |
239 | } | |
240 | if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) && | |
bffe9ae3 | 241 | (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_PTRACE)) |
871851e7 | 242 | side_ptrace_hook(event_state, side_arg_vec, var_struct); |
67337c4a | 243 | } |
873bbf16 | 244 | side_rcu_read_begin(&event_rcu_gp, &rcu_read_state); |
92c377f9 | 245 | for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) { |
bffe9ae3 | 246 | if (key != SIDE_KEY_MATCH_ALL && side_cb->key != SIDE_KEY_MATCH_ALL && side_cb->key != key) |
92c377f9 | 247 | continue; |
7269a8a3 | 248 | side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv); |
92c377f9 | 249 | } |
873bbf16 | 250 | side_rcu_read_end(&event_rcu_gp, &rcu_read_state); |
67337c4a MD |
251 | } |
252 | ||
92c377f9 | 253 | void side_call_variadic(const struct side_event_state *event_state, |
e7f33720 MD |
254 | const struct side_arg_vec *side_arg_vec, |
255 | const struct side_arg_dynamic_struct *var_struct) | |
92c377f9 | 256 | { |
bffe9ae3 | 257 | _side_call_variadic(event_state, side_arg_vec, var_struct, SIDE_KEY_MATCH_ALL); |
74be90b7 MD |
258 | } |
259 | ||
f0b01832 | 260 | void side_statedump_call_variadic(const struct side_event_state *event_state, |
3da13b2c MD |
261 | const struct side_arg_vec *side_arg_vec, |
262 | const struct side_arg_dynamic_struct *var_struct, | |
263 | void *statedump_request_key) | |
74be90b7 | 264 | { |
3da13b2c | 265 | _side_call_variadic(event_state, side_arg_vec, var_struct, *(const uint64_t *) statedump_request_key); |
92c377f9 MD |
266 | } |
267 | ||
67337c4a MD |
268 | static |
269 | const struct side_callback *side_tracer_callback_lookup( | |
270 | const struct side_event_description *desc, | |
bffe9ae3 | 271 | void *call, void *priv, uint64_t key) |
67337c4a | 272 | { |
0b9e59d6 | 273 | struct side_event_state *event_state = side_ptr_get(desc->state); |
b2a84b9f | 274 | const struct side_event_state_0 *es0; |
67337c4a MD |
275 | const struct side_callback *cb; |
276 | ||
b2a84b9f MD |
277 | if (side_unlikely(event_state->version != 0)) |
278 | abort(); | |
49aea3ef | 279 | es0 = side_container_of(event_state, const struct side_event_state_0, parent); |
7269a8a3 | 280 | for (cb = es0->callbacks; cb->u.call != NULL; cb++) { |
92c377f9 | 281 | if ((void *) cb->u.call == call && cb->priv == priv && cb->key == key) |
67337c4a MD |
282 | return cb; |
283 | } | |
284 | return NULL; | |
285 | } | |
286 | ||
287 | static | |
288 | int _side_tracer_callback_register(struct side_event_description *desc, | |
bffe9ae3 | 289 | void *call, void *priv, uint64_t key) |
67337c4a | 290 | { |
0b9e59d6 | 291 | struct side_event_state *event_state; |
67337c4a | 292 | struct side_callback *old_cb, *new_cb; |
b2a84b9f | 293 | struct side_event_state_0 *es0; |
67337c4a MD |
294 | int ret = SIDE_ERROR_OK; |
295 | uint32_t old_nr_cb; | |
296 | ||
297 | if (!call) | |
298 | return SIDE_ERROR_INVAL; | |
299 | if (finalized) | |
300 | return SIDE_ERROR_EXITING; | |
301 | if (!initialized) | |
302 | side_init(); | |
873bbf16 | 303 | pthread_mutex_lock(&side_event_lock); |
0b9e59d6 | 304 | event_state = side_ptr_get(desc->state); |
b2a84b9f MD |
305 | if (side_unlikely(event_state->version != 0)) |
306 | abort(); | |
49aea3ef | 307 | es0 = side_container_of(event_state, struct side_event_state_0, parent); |
3cac1780 | 308 | old_nr_cb = es0->nr_callbacks; |
67337c4a MD |
309 | if (old_nr_cb == UINT32_MAX) { |
310 | ret = SIDE_ERROR_INVAL; | |
311 | goto unlock; | |
312 | } | |
313 | /* Reject duplicate (call, priv) tuples. */ | |
92c377f9 | 314 | if (side_tracer_callback_lookup(desc, call, priv, key)) { |
67337c4a MD |
315 | ret = SIDE_ERROR_EXIST; |
316 | goto unlock; | |
317 | } | |
7269a8a3 | 318 | old_cb = (struct side_callback *) es0->callbacks; |
67337c4a MD |
319 | /* old_nr_cb + 1 (new cb) + 1 (NULL) */ |
320 | new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback)); | |
321 | if (!new_cb) { | |
322 | ret = SIDE_ERROR_NOMEM; | |
323 | goto unlock; | |
324 | } | |
325 | memcpy(new_cb, old_cb, old_nr_cb); | |
326 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
327 | new_cb[old_nr_cb].u.call_variadic = | |
328 | (side_tracer_callback_variadic_func) call; | |
329 | else | |
330 | new_cb[old_nr_cb].u.call = | |
331 | (side_tracer_callback_func) call; | |
332 | new_cb[old_nr_cb].priv = priv; | |
92c377f9 | 333 | new_cb[old_nr_cb].key = key; |
f60d8121 | 334 | /* High order bits are already zeroed. */ |
7269a8a3 | 335 | side_rcu_assign_pointer(es0->callbacks, new_cb); |
873bbf16 | 336 | side_rcu_wait_grace_period(&event_rcu_gp); |
67337c4a MD |
337 | if (old_nr_cb) |
338 | free(old_cb); | |
3cac1780 | 339 | es0->nr_callbacks++; |
67337c4a MD |
340 | /* Increment concurrently with kernel setting the top bits. */ |
341 | if (!old_nr_cb) | |
b2a84b9f | 342 | (void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED); |
67337c4a | 343 | unlock: |
873bbf16 | 344 | pthread_mutex_unlock(&side_event_lock); |
67337c4a MD |
345 | return ret; |
346 | } | |
347 | ||
348 | int side_tracer_callback_register(struct side_event_description *desc, | |
349 | side_tracer_callback_func call, | |
bffe9ae3 | 350 | void *priv, uint64_t key) |
67337c4a MD |
351 | { |
352 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
353 | return SIDE_ERROR_INVAL; | |
92c377f9 | 354 | return _side_tracer_callback_register(desc, (void *) call, priv, key); |
67337c4a MD |
355 | } |
356 | ||
357 | int side_tracer_callback_variadic_register(struct side_event_description *desc, | |
358 | side_tracer_callback_variadic_func call_variadic, | |
bffe9ae3 | 359 | void *priv, uint64_t key) |
67337c4a MD |
360 | { |
361 | if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) | |
362 | return SIDE_ERROR_INVAL; | |
92c377f9 | 363 | return _side_tracer_callback_register(desc, (void *) call_variadic, priv, key); |
67337c4a MD |
364 | } |
365 | ||
366 | static int _side_tracer_callback_unregister(struct side_event_description *desc, | |
bffe9ae3 | 367 | void *call, void *priv, uint64_t key) |
67337c4a | 368 | { |
0b9e59d6 | 369 | struct side_event_state *event_state; |
67337c4a MD |
370 | struct side_callback *old_cb, *new_cb; |
371 | const struct side_callback *cb_pos; | |
b2a84b9f | 372 | struct side_event_state_0 *es0; |
67337c4a MD |
373 | uint32_t pos_idx; |
374 | int ret = SIDE_ERROR_OK; | |
375 | uint32_t old_nr_cb; | |
376 | ||
377 | if (!call) | |
378 | return SIDE_ERROR_INVAL; | |
379 | if (finalized) | |
380 | return SIDE_ERROR_EXITING; | |
381 | if (!initialized) | |
382 | side_init(); | |
873bbf16 | 383 | pthread_mutex_lock(&side_event_lock); |
0b9e59d6 | 384 | event_state = side_ptr_get(desc->state); |
b2a84b9f MD |
385 | if (side_unlikely(event_state->version != 0)) |
386 | abort(); | |
49aea3ef | 387 | es0 = side_container_of(event_state, struct side_event_state_0, parent); |
92c377f9 | 388 | cb_pos = side_tracer_callback_lookup(desc, call, priv, key); |
67337c4a MD |
389 | if (!cb_pos) { |
390 | ret = SIDE_ERROR_NOENT; | |
391 | goto unlock; | |
392 | } | |
3cac1780 | 393 | old_nr_cb = es0->nr_callbacks; |
7269a8a3 | 394 | old_cb = (struct side_callback *) es0->callbacks; |
67337c4a MD |
395 | if (old_nr_cb == 1) { |
396 | new_cb = (struct side_callback *) &side_empty_callback; | |
397 | } else { | |
7269a8a3 | 398 | pos_idx = cb_pos - es0->callbacks; |
67337c4a MD |
399 | /* Remove entry at pos_idx. */ |
400 | /* old_nr_cb - 1 (removed cb) + 1 (NULL) */ | |
401 | new_cb = (struct side_callback *) calloc(old_nr_cb, sizeof(struct side_callback)); | |
402 | if (!new_cb) { | |
403 | ret = SIDE_ERROR_NOMEM; | |
404 | goto unlock; | |
405 | } | |
406 | memcpy(new_cb, old_cb, pos_idx); | |
407 | memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1); | |
408 | } | |
f60d8121 | 409 | /* High order bits are already zeroed. */ |
7269a8a3 | 410 | side_rcu_assign_pointer(es0->callbacks, new_cb); |
873bbf16 | 411 | side_rcu_wait_grace_period(&event_rcu_gp); |
67337c4a | 412 | free(old_cb); |
3cac1780 | 413 | es0->nr_callbacks--; |
67337c4a MD |
414 | /* Decrement concurrently with kernel setting the top bits. */ |
415 | if (old_nr_cb == 1) | |
b2a84b9f | 416 | (void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED); |
67337c4a | 417 | unlock: |
873bbf16 | 418 | pthread_mutex_unlock(&side_event_lock); |
67337c4a MD |
419 | return ret; |
420 | } | |
421 | ||
422 | int side_tracer_callback_unregister(struct side_event_description *desc, | |
423 | side_tracer_callback_func call, | |
bffe9ae3 | 424 | void *priv, uint64_t key) |
67337c4a MD |
425 | { |
426 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
427 | return SIDE_ERROR_INVAL; | |
92c377f9 | 428 | return _side_tracer_callback_unregister(desc, (void *) call, priv, key); |
67337c4a MD |
429 | } |
430 | ||
431 | int side_tracer_callback_variadic_unregister(struct side_event_description *desc, | |
432 | side_tracer_callback_variadic_func call_variadic, | |
bffe9ae3 | 433 | void *priv, uint64_t key) |
67337c4a MD |
434 | { |
435 | if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) | |
436 | return SIDE_ERROR_INVAL; | |
92c377f9 | 437 | return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv, key); |
67337c4a MD |
438 | } |
439 | ||
440 | struct side_events_register_handle *side_events_register(struct side_event_description **events, uint32_t nr_events) | |
441 | { | |
442 | struct side_events_register_handle *events_handle = NULL; | |
443 | struct side_tracer_handle *tracer_handle; | |
444 | ||
445 | if (finalized) | |
446 | return NULL; | |
447 | if (!initialized) | |
448 | side_init(); | |
449 | events_handle = (struct side_events_register_handle *) | |
450 | calloc(1, sizeof(struct side_events_register_handle)); | |
451 | if (!events_handle) | |
452 | return NULL; | |
453 | events_handle->events = events; | |
454 | events_handle->nr_events = nr_events; | |
455 | ||
873bbf16 | 456 | pthread_mutex_lock(&side_event_lock); |
67337c4a MD |
457 | side_list_insert_node_tail(&side_events_list, &events_handle->node); |
458 | side_list_for_each_entry(tracer_handle, &side_tracer_list, node) { | |
459 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS, | |
460 | events, nr_events, tracer_handle->priv); | |
461 | } | |
873bbf16 | 462 | pthread_mutex_unlock(&side_event_lock); |
67337c4a MD |
463 | //TODO: call event batch register ioctl |
464 | return events_handle; | |
465 | } | |
466 | ||
467 | static | |
468 | void side_event_remove_callbacks(struct side_event_description *desc) | |
469 | { | |
0b9e59d6 | 470 | struct side_event_state *event_state = side_ptr_get(desc->state); |
b2a84b9f | 471 | struct side_event_state_0 *es0; |
67337c4a | 472 | struct side_callback *old_cb; |
3cac1780 | 473 | uint32_t nr_cb; |
67337c4a | 474 | |
b2a84b9f MD |
475 | if (side_unlikely(event_state->version != 0)) |
476 | abort(); | |
49aea3ef | 477 | es0 = side_container_of(event_state, struct side_event_state_0, parent); |
3cac1780 MD |
478 | nr_cb = es0->nr_callbacks; |
479 | if (!nr_cb) | |
480 | return; | |
7269a8a3 | 481 | old_cb = (struct side_callback *) es0->callbacks; |
b2a84b9f | 482 | (void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED); |
67337c4a MD |
483 | /* |
484 | * Setting the state back to 0 cb and empty callbacks out of | |
485 | * caution. This should not matter because instrumentation is | |
486 | * unreachable. | |
487 | */ | |
3cac1780 | 488 | es0->nr_callbacks = 0; |
7269a8a3 | 489 | side_rcu_assign_pointer(es0->callbacks, &side_empty_callback); |
67337c4a MD |
490 | /* |
491 | * No need to wait for grace period because instrumentation is | |
492 | * unreachable. | |
493 | */ | |
494 | free(old_cb); | |
495 | } | |
496 | ||
497 | /* | |
498 | * Unregister event handle. At this point, all side events in that | |
499 | * handle should be unreachable. | |
500 | */ | |
501 | void side_events_unregister(struct side_events_register_handle *events_handle) | |
502 | { | |
503 | struct side_tracer_handle *tracer_handle; | |
504 | uint32_t i; | |
505 | ||
506 | if (!events_handle) | |
507 | return; | |
508 | if (finalized) | |
509 | return; | |
510 | if (!initialized) | |
511 | side_init(); | |
873bbf16 | 512 | pthread_mutex_lock(&side_event_lock); |
67337c4a MD |
513 | side_list_remove_node(&events_handle->node); |
514 | side_list_for_each_entry(tracer_handle, &side_tracer_list, node) { | |
515 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS, | |
516 | events_handle->events, events_handle->nr_events, | |
517 | tracer_handle->priv); | |
518 | } | |
519 | for (i = 0; i < events_handle->nr_events; i++) { | |
520 | struct side_event_description *event = events_handle->events[i]; | |
521 | ||
522 | /* Skip NULL pointers */ | |
523 | if (!event) | |
524 | continue; | |
525 | side_event_remove_callbacks(event); | |
526 | } | |
873bbf16 | 527 | pthread_mutex_unlock(&side_event_lock); |
67337c4a MD |
528 | //TODO: call event batch unregister ioctl |
529 | free(events_handle); | |
530 | } | |
531 | ||
532 | struct side_tracer_handle *side_tracer_event_notification_register( | |
533 | void (*cb)(enum side_tracer_notification notif, | |
534 | struct side_event_description **events, uint32_t nr_events, void *priv), | |
535 | void *priv) | |
536 | { | |
537 | struct side_tracer_handle *tracer_handle; | |
538 | struct side_events_register_handle *events_handle; | |
539 | ||
540 | if (finalized) | |
541 | return NULL; | |
542 | if (!initialized) | |
543 | side_init(); | |
544 | tracer_handle = (struct side_tracer_handle *) | |
545 | calloc(1, sizeof(struct side_tracer_handle)); | |
546 | if (!tracer_handle) | |
547 | return NULL; | |
873bbf16 | 548 | pthread_mutex_lock(&side_event_lock); |
67337c4a MD |
549 | tracer_handle->cb = cb; |
550 | tracer_handle->priv = priv; | |
551 | side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node); | |
552 | side_list_for_each_entry(events_handle, &side_events_list, node) { | |
553 | cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS, | |
554 | events_handle->events, events_handle->nr_events, priv); | |
555 | } | |
873bbf16 | 556 | pthread_mutex_unlock(&side_event_lock); |
67337c4a MD |
557 | return tracer_handle; |
558 | } | |
559 | ||
560 | void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle) | |
561 | { | |
562 | struct side_events_register_handle *events_handle; | |
563 | ||
564 | if (finalized) | |
565 | return; | |
566 | if (!initialized) | |
567 | side_init(); | |
873bbf16 | 568 | pthread_mutex_lock(&side_event_lock); |
67337c4a MD |
569 | side_list_for_each_entry(events_handle, &side_events_list, node) { |
570 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS, | |
571 | events_handle->events, events_handle->nr_events, | |
572 | tracer_handle->priv); | |
573 | } | |
574 | side_list_remove_node(&tracer_handle->node); | |
873bbf16 | 575 | pthread_mutex_unlock(&side_event_lock); |
be787080 | 576 | free(tracer_handle); |
67337c4a MD |
577 | } |
578 | ||
bffe9ae3 MD |
579 | /* Called with side_statedump_lock held. */ |
580 | static | |
581 | void queue_statedump_pending(struct side_statedump_request_handle *handle, uint64_t key) | |
582 | { | |
583 | struct side_statedump_notification *notif; | |
584 | ||
585 | notif = (struct side_statedump_notification *) calloc(1, sizeof(struct side_statedump_notification)); | |
586 | if (!notif) | |
587 | abort(); | |
588 | notif->key = key; | |
589 | side_list_insert_node_tail(&handle->notification_queue, ¬if->node); | |
76dd11f9 | 590 | if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) { |
a125f217 | 591 | (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_HANDLE_REQUEST, __ATOMIC_SEQ_CST); |
76dd11f9 MD |
592 | pthread_cond_broadcast(&statedump_agent_thread.worker_cond); |
593 | } | |
bffe9ae3 MD |
594 | } |
595 | ||
596 | /* Called with side_statedump_lock held. */ | |
597 | static | |
598 | void unqueue_statedump_pending(struct side_statedump_request_handle *handle, uint64_t key) | |
599 | { | |
600 | struct side_statedump_notification *notif, *tmp; | |
601 | ||
602 | side_list_for_each_entry_safe(notif, tmp, &handle->notification_queue, node) { | |
603 | if (key == SIDE_KEY_MATCH_ALL || key == notif->key) { | |
604 | side_list_remove_node(¬if->node); | |
605 | free(notif); | |
606 | } | |
607 | } | |
608 | } | |
609 | ||
a125f217 MD |
610 | static |
611 | void side_statedump_run(struct side_statedump_request_handle *handle, | |
612 | struct side_statedump_notification *notif) | |
613 | { | |
3da13b2c | 614 | side_statedump_event_call(side_statedump_begin, ¬if->key, |
a125f217 | 615 | side_arg_list(side_arg_string(handle->name))); |
3da13b2c MD |
616 | /* Invoke the state dump callback specifically for the tracer key. */ |
617 | handle->cb(¬if->key); | |
618 | side_statedump_event_call(side_statedump_end, ¬if->key, | |
a125f217 | 619 | side_arg_list(side_arg_string(handle->name))); |
a125f217 MD |
620 | } |
621 | ||
622 | static | |
623 | void _side_statedump_run_pending_requests(struct side_statedump_request_handle *handle) | |
624 | { | |
625 | struct side_statedump_notification *notif, *tmp; | |
626 | DEFINE_SIDE_LIST_HEAD(tmp_head); | |
627 | ||
628 | pthread_mutex_lock(&side_statedump_lock); | |
629 | side_list_splice(&handle->notification_queue, &tmp_head); | |
630 | side_list_head_init(&handle->notification_queue); | |
631 | pthread_mutex_unlock(&side_statedump_lock); | |
632 | ||
633 | /* We are now sole owner of the tmp_head list. */ | |
634 | side_list_for_each_entry(notif, &tmp_head, node) | |
635 | side_statedump_run(handle, notif); | |
636 | side_list_for_each_entry_safe(notif, tmp, &tmp_head, node) | |
637 | free(notif); | |
76dd11f9 MD |
638 | |
639 | if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) { | |
640 | pthread_mutex_lock(&side_statedump_lock); | |
641 | pthread_cond_broadcast(&statedump_agent_thread.waiter_cond); | |
642 | pthread_mutex_unlock(&side_statedump_lock); | |
643 | } | |
a125f217 MD |
644 | } |
645 | ||
646 | static | |
647 | void *statedump_agent_func(void *arg __attribute__((unused))) | |
648 | { | |
649 | for (;;) { | |
650 | struct side_statedump_request_handle *handle; | |
651 | struct side_rcu_read_state rcu_read_state; | |
652 | enum agent_thread_state state; | |
653 | ||
76dd11f9 MD |
654 | pthread_mutex_lock(&side_statedump_lock); |
655 | for (;;) { | |
656 | state = __atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST); | |
657 | if (state == AGENT_THREAD_STATE_BLOCKED) | |
658 | pthread_cond_wait(&statedump_agent_thread.worker_cond, &side_statedump_lock); | |
659 | else | |
660 | break; | |
a125f217 | 661 | } |
76dd11f9 | 662 | pthread_mutex_unlock(&side_statedump_lock); |
a125f217 MD |
663 | if (state & AGENT_THREAD_STATE_EXIT) |
664 | break; | |
7e38dc2e MD |
665 | if (state & AGENT_THREAD_STATE_PAUSE) { |
666 | int attempt = 0; | |
667 | ||
668 | (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_PAUSE_ACK, __ATOMIC_SEQ_CST); | |
669 | for (;;) { | |
670 | state = __atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST); | |
671 | if (!(state & AGENT_THREAD_STATE_PAUSE)) | |
672 | break; | |
673 | if (attempt > SIDE_RETRY_BUSY_LOOP_ATTEMPTS) { | |
674 | (void)poll(NULL, 0, SIDE_RETRY_DELAY_MS); | |
675 | continue; | |
676 | } | |
677 | attempt++; | |
678 | side_cpu_relax(); | |
679 | } | |
680 | continue; | |
681 | } | |
a125f217 MD |
682 | (void)__atomic_and_fetch(&statedump_agent_thread.state, ~AGENT_THREAD_STATE_HANDLE_REQUEST, __ATOMIC_SEQ_CST); |
683 | side_rcu_read_begin(&statedump_rcu_gp, &rcu_read_state); | |
684 | side_list_for_each_entry_rcu(handle, &side_statedump_list, node) | |
685 | _side_statedump_run_pending_requests(handle); | |
686 | side_rcu_read_end(&statedump_rcu_gp, &rcu_read_state); | |
687 | } | |
688 | return NULL; | |
689 | } | |
690 | ||
7e38dc2e MD |
691 | static |
692 | void statedump_agent_thread_init(void) | |
693 | { | |
694 | pthread_cond_init(&statedump_agent_thread.worker_cond, NULL); | |
695 | pthread_cond_init(&statedump_agent_thread.waiter_cond, NULL); | |
696 | statedump_agent_thread.state = AGENT_THREAD_STATE_BLOCKED; | |
697 | } | |
698 | ||
76dd11f9 | 699 | /* Called with side_agent_thread_lock and side_statedump_lock held. */ |
a125f217 MD |
700 | static |
701 | void statedump_agent_thread_get(void) | |
702 | { | |
703 | int ret; | |
704 | ||
705 | if (statedump_agent_thread.ref++) | |
706 | return; | |
7e38dc2e | 707 | statedump_agent_thread_init(); |
a125f217 MD |
708 | ret = pthread_create(&statedump_agent_thread.id, NULL, |
709 | statedump_agent_func, NULL); | |
710 | if (ret) { | |
711 | abort(); | |
712 | } | |
713 | } | |
714 | ||
76dd11f9 MD |
715 | /* |
716 | * Called with side_agent_thread_lock and side_statedump_lock held. | |
717 | * Returns true if join for agent thread is needed. | |
718 | */ | |
719 | static | |
720 | bool statedump_agent_thread_put(void) | |
721 | { | |
722 | if (--statedump_agent_thread.ref) | |
723 | return false; | |
724 | (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_EXIT, __ATOMIC_SEQ_CST); | |
725 | pthread_cond_broadcast(&statedump_agent_thread.worker_cond); | |
726 | return true; | |
727 | } | |
728 | ||
7e38dc2e MD |
729 | static |
730 | void statedump_agent_thread_fini(void) | |
731 | { | |
732 | statedump_agent_thread.state = AGENT_THREAD_STATE_BLOCKED; | |
733 | if (pthread_cond_destroy(&statedump_agent_thread.worker_cond)) | |
734 | abort(); | |
735 | if (pthread_cond_destroy(&statedump_agent_thread.waiter_cond)) | |
736 | abort(); | |
737 | } | |
738 | ||
76dd11f9 | 739 | /* Called with side_agent_thread_lock held. */ |
a125f217 | 740 | static |
76dd11f9 | 741 | void statedump_agent_thread_join(void) |
a125f217 MD |
742 | { |
743 | int ret; | |
744 | void *retval; | |
745 | ||
a125f217 MD |
746 | ret = pthread_join(statedump_agent_thread.id, &retval); |
747 | if (ret) { | |
748 | abort(); | |
749 | } | |
7e38dc2e | 750 | statedump_agent_thread_fini(); |
a125f217 MD |
751 | } |
752 | ||
bffe9ae3 MD |
753 | struct side_statedump_request_handle * |
754 | side_statedump_request_notification_register(const char *state_name, | |
3da13b2c | 755 | void (*statedump_cb)(void *statedump_request_key), |
bffe9ae3 | 756 | enum side_statedump_mode mode) |
f0b01832 MD |
757 | { |
758 | struct side_statedump_request_handle *handle; | |
bffe9ae3 | 759 | char *name; |
f0b01832 MD |
760 | |
761 | if (finalized) | |
762 | return NULL; | |
763 | if (!initialized) | |
764 | side_init(); | |
f0b01832 MD |
765 | handle = (struct side_statedump_request_handle *) |
766 | calloc(1, sizeof(struct side_statedump_request_handle)); | |
767 | if (!handle) | |
768 | return NULL; | |
bffe9ae3 MD |
769 | name = strdup(state_name); |
770 | if (!name) | |
771 | goto name_nomem; | |
f0b01832 | 772 | handle->cb = statedump_cb; |
bffe9ae3 MD |
773 | handle->name = name; |
774 | handle->mode = mode; | |
775 | side_list_head_init(&handle->notification_queue); | |
873bbf16 | 776 | |
76dd11f9 MD |
777 | if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) |
778 | pthread_mutex_lock(&side_agent_thread_lock); | |
873bbf16 | 779 | pthread_mutex_lock(&side_statedump_lock); |
a125f217 MD |
780 | if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) |
781 | statedump_agent_thread_get(); | |
873bbf16 | 782 | side_list_insert_node_tail_rcu(&side_statedump_list, &handle->node); |
bffe9ae3 MD |
783 | /* Queue statedump pending for all tracers. */ |
784 | queue_statedump_pending(handle, SIDE_KEY_MATCH_ALL); | |
873bbf16 MD |
785 | pthread_mutex_unlock(&side_statedump_lock); |
786 | ||
a125f217 | 787 | if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) { |
76dd11f9 | 788 | pthread_mutex_unlock(&side_agent_thread_lock); |
a125f217 | 789 | |
76dd11f9 MD |
790 | pthread_mutex_lock(&side_statedump_lock); |
791 | while (!side_list_empty(&handle->notification_queue)) | |
792 | pthread_cond_wait(&statedump_agent_thread.waiter_cond, &side_statedump_lock); | |
793 | pthread_mutex_unlock(&side_statedump_lock); | |
a125f217 MD |
794 | } |
795 | ||
f0b01832 | 796 | return handle; |
bffe9ae3 MD |
797 | |
798 | name_nomem: | |
799 | free(handle); | |
800 | return NULL; | |
f0b01832 MD |
801 | } |
802 | ||
803 | void side_statedump_request_notification_unregister(struct side_statedump_request_handle *handle) | |
804 | { | |
76dd11f9 MD |
805 | bool join = false; |
806 | ||
f0b01832 MD |
807 | if (finalized) |
808 | return; | |
809 | if (!initialized) | |
810 | side_init(); | |
873bbf16 | 811 | |
76dd11f9 MD |
812 | if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) |
813 | pthread_mutex_lock(&side_agent_thread_lock); | |
873bbf16 | 814 | pthread_mutex_lock(&side_statedump_lock); |
bffe9ae3 | 815 | unqueue_statedump_pending(handle, SIDE_KEY_MATCH_ALL); |
873bbf16 | 816 | side_list_remove_node_rcu(&handle->node); |
a125f217 | 817 | if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) |
76dd11f9 | 818 | join = statedump_agent_thread_put(); |
873bbf16 | 819 | pthread_mutex_unlock(&side_statedump_lock); |
76dd11f9 MD |
820 | if (join) |
821 | statedump_agent_thread_join(); | |
822 | if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) | |
823 | pthread_mutex_unlock(&side_agent_thread_lock); | |
873bbf16 MD |
824 | |
825 | side_rcu_wait_grace_period(&statedump_rcu_gp); | |
bffe9ae3 | 826 | free(handle->name); |
f0b01832 MD |
827 | free(handle); |
828 | } | |
829 | ||
bffe9ae3 MD |
830 | /* Returns true if the handle has pending statedump requests. */ |
831 | bool side_statedump_poll_pending_requests(struct side_statedump_request_handle *handle) | |
f0b01832 | 832 | { |
bffe9ae3 MD |
833 | bool ret; |
834 | ||
835 | if (handle->mode != SIDE_STATEDUMP_MODE_POLLING) | |
836 | return false; | |
837 | pthread_mutex_lock(&side_statedump_lock); | |
838 | ret = !side_list_empty(&handle->notification_queue); | |
839 | pthread_mutex_unlock(&side_statedump_lock); | |
840 | return ret; | |
841 | } | |
f0b01832 | 842 | |
bffe9ae3 MD |
843 | /* |
844 | * Only polling mode state dump handles allow application to explicitly handle the | |
845 | * pending requests. | |
846 | */ | |
847 | int side_statedump_run_pending_requests(struct side_statedump_request_handle *handle) | |
848 | { | |
849 | if (handle->mode != SIDE_STATEDUMP_MODE_POLLING) | |
850 | return SIDE_ERROR_INVAL; | |
851 | _side_statedump_run_pending_requests(handle); | |
852 | return SIDE_ERROR_OK; | |
853 | } | |
854 | ||
855 | /* | |
856 | * Request a state dump for tracer callbacks identified with "key". | |
857 | */ | |
858 | int side_tracer_statedump_request(uint64_t key) | |
859 | { | |
860 | struct side_statedump_request_handle *handle; | |
861 | ||
862 | if (key == SIDE_KEY_MATCH_ALL) | |
863 | return SIDE_ERROR_INVAL; | |
864 | pthread_mutex_lock(&side_statedump_lock); | |
865 | side_list_for_each_entry(handle, &side_statedump_list, node) | |
866 | queue_statedump_pending(handle, key); | |
867 | pthread_mutex_lock(&side_statedump_lock); | |
868 | return SIDE_ERROR_OK; | |
869 | } | |
870 | ||
871 | /* | |
872 | * Cancel a statedump request. | |
873 | */ | |
874 | int side_tracer_statedump_request_cancel(uint64_t key) | |
875 | { | |
876 | struct side_statedump_request_handle *handle; | |
877 | ||
878 | if (key == SIDE_KEY_MATCH_ALL) | |
879 | return SIDE_ERROR_INVAL; | |
880 | pthread_mutex_lock(&side_statedump_lock); | |
881 | side_list_for_each_entry(handle, &side_statedump_list, node) | |
882 | unqueue_statedump_pending(handle, key); | |
883 | pthread_mutex_lock(&side_statedump_lock); | |
884 | return SIDE_ERROR_OK; | |
885 | } | |
886 | ||
887 | /* | |
888 | * Tracer keys are represented on 64-bit. Return SIDE_ERROR_NOMEM on | |
889 | * overflow (which should never happen in practice). | |
890 | */ | |
891 | int side_tracer_request_key(uint64_t *key) | |
892 | { | |
893 | int ret = SIDE_ERROR_OK; | |
894 | ||
895 | pthread_mutex_lock(&side_key_lock); | |
896 | if (side_key_next == 0) { | |
897 | ret = SIDE_ERROR_NOMEM; | |
898 | goto end; | |
899 | } | |
900 | *key = side_key_next++; | |
901 | end: | |
902 | pthread_mutex_unlock(&side_key_lock); | |
903 | return ret; | |
f0b01832 MD |
904 | } |
905 | ||
7e38dc2e MD |
906 | /* |
907 | * Use of pthread_atfork depends on glibc 2.24 to eliminate hangs when | |
908 | * waiting for the agent thread if the agent thread calls malloc. This | |
909 | * is corrected by GNU libc | |
910 | * commit 8a727af925be63aa6ea0f5f90e16751fd541626b. | |
911 | * Ref. https://bugzilla.redhat.com/show_bug.cgi?id=906468 | |
912 | */ | |
913 | static | |
914 | void side_before_fork(void) | |
915 | { | |
916 | int attempt = 0; | |
917 | ||
918 | pthread_mutex_lock(&side_agent_thread_lock); | |
919 | if (!statedump_agent_thread.ref) | |
920 | return; | |
921 | /* Pause agent thread. */ | |
922 | pthread_mutex_lock(&side_statedump_lock); | |
923 | (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_PAUSE, __ATOMIC_SEQ_CST); | |
924 | pthread_cond_broadcast(&statedump_agent_thread.worker_cond); | |
925 | pthread_mutex_unlock(&side_statedump_lock); | |
926 | /* Wait for agent thread acknowledge. */ | |
927 | while (!(__atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST) & AGENT_THREAD_STATE_PAUSE_ACK)) { | |
928 | if (attempt > SIDE_RETRY_BUSY_LOOP_ATTEMPTS) { | |
929 | (void)poll(NULL, 0, SIDE_RETRY_DELAY_MS); | |
930 | continue; | |
931 | } | |
932 | attempt++; | |
933 | side_cpu_relax(); | |
934 | } | |
935 | } | |
936 | ||
937 | static | |
938 | void side_after_fork_parent(void) | |
939 | { | |
940 | if (statedump_agent_thread.ref) | |
941 | (void)__atomic_and_fetch(&statedump_agent_thread.state, | |
942 | ~(AGENT_THREAD_STATE_PAUSE | AGENT_THREAD_STATE_PAUSE_ACK), | |
943 | __ATOMIC_SEQ_CST); | |
944 | pthread_mutex_unlock(&side_agent_thread_lock); | |
945 | } | |
946 | ||
947 | /* | |
948 | * The agent thread does not exist in the child process after a fork. | |
949 | * Re-initialize its data structures and create a new agent thread. | |
950 | */ | |
951 | static | |
952 | void side_after_fork_child(void) | |
953 | { | |
954 | if (statedump_agent_thread.ref) { | |
955 | int ret; | |
956 | ||
957 | statedump_agent_thread_fini(); | |
958 | statedump_agent_thread_init(); | |
959 | ret = pthread_create(&statedump_agent_thread.id, NULL, | |
960 | statedump_agent_func, NULL); | |
961 | if (ret) { | |
962 | abort(); | |
963 | } | |
964 | } | |
965 | pthread_mutex_unlock(&side_agent_thread_lock); | |
966 | } | |
967 | ||
67337c4a MD |
968 | void side_init(void) |
969 | { | |
970 | if (initialized) | |
971 | return; | |
873bbf16 MD |
972 | side_rcu_gp_init(&event_rcu_gp); |
973 | side_rcu_gp_init(&statedump_rcu_gp); | |
7e38dc2e MD |
974 | if (pthread_atfork(side_before_fork, side_after_fork_parent, side_after_fork_child)) |
975 | abort(); | |
67337c4a MD |
976 | initialized = true; |
977 | } | |
978 | ||
979 | /* | |
980 | * side_exit() is executed from a library destructor. It can be called | |
981 | * explicitly at application exit as well. Concurrent side API use is | |
982 | * not expected at that point. | |
983 | */ | |
984 | void side_exit(void) | |
985 | { | |
986 | struct side_events_register_handle *handle, *tmp; | |
987 | ||
988 | if (finalized) | |
989 | return; | |
990 | side_list_for_each_entry_safe(handle, tmp, &side_events_list, node) | |
991 | side_events_unregister(handle); | |
873bbf16 MD |
992 | side_rcu_gp_exit(&event_rcu_gp); |
993 | side_rcu_gp_exit(&statedump_rcu_gp); | |
67337c4a MD |
994 | finalized = true; |
995 | } |