Jens Axboe | 771b53d0 | 2019-10-22 10:25:58 -0600 | [diff] [blame^] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * Basic worker thread pool for io_uring |
| 4 | * |
| 5 | * Copyright (C) 2019 Jens Axboe |
| 6 | * |
| 7 | */ |
| 8 | #include <linux/kernel.h> |
| 9 | #include <linux/init.h> |
| 10 | #include <linux/errno.h> |
| 11 | #include <linux/sched/signal.h> |
| 12 | #include <linux/mm.h> |
| 13 | #include <linux/mmu_context.h> |
| 14 | #include <linux/sched/mm.h> |
| 15 | #include <linux/percpu.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/kthread.h> |
| 18 | #include <linux/rculist_nulls.h> |
| 19 | |
| 20 | #include "io-wq.h" |
| 21 | |
| 22 | #define WORKER_IDLE_TIMEOUT (5 * HZ) |
| 23 | |
| 24 | enum { |
| 25 | IO_WORKER_F_UP = 1, /* up and active */ |
| 26 | IO_WORKER_F_RUNNING = 2, /* account as running */ |
| 27 | IO_WORKER_F_FREE = 4, /* worker on free list */ |
| 28 | IO_WORKER_F_EXITING = 8, /* worker exiting */ |
| 29 | IO_WORKER_F_FIXED = 16, /* static idle worker */ |
| 30 | }; |
| 31 | |
| 32 | enum { |
| 33 | IO_WQ_BIT_EXIT = 0, /* wq exiting */ |
| 34 | IO_WQ_BIT_CANCEL = 1, /* cancel work on list */ |
| 35 | }; |
| 36 | |
| 37 | enum { |
| 38 | IO_WQE_FLAG_STALLED = 1, /* stalled on hash */ |
| 39 | }; |
| 40 | |
| 41 | /* |
| 42 | * One for each thread in a wqe pool |
| 43 | */ |
| 44 | struct io_worker { |
| 45 | refcount_t ref; |
| 46 | unsigned flags; |
| 47 | struct hlist_nulls_node nulls_node; |
| 48 | struct task_struct *task; |
| 49 | wait_queue_head_t wait; |
| 50 | struct io_wqe *wqe; |
| 51 | struct io_wq_work *cur_work; |
| 52 | |
| 53 | struct rcu_head rcu; |
| 54 | struct mm_struct *mm; |
| 55 | }; |
| 56 | |
| 57 | struct io_wq_nulls_list { |
| 58 | struct hlist_nulls_head head; |
| 59 | unsigned long nulls; |
| 60 | }; |
| 61 | |
| 62 | #if BITS_PER_LONG == 64 |
| 63 | #define IO_WQ_HASH_ORDER 6 |
| 64 | #else |
| 65 | #define IO_WQ_HASH_ORDER 5 |
| 66 | #endif |
| 67 | |
| 68 | /* |
| 69 | * Per-node worker thread pool |
| 70 | */ |
| 71 | struct io_wqe { |
| 72 | struct { |
| 73 | spinlock_t lock; |
| 74 | struct list_head work_list; |
| 75 | unsigned long hash_map; |
| 76 | unsigned flags; |
| 77 | } ____cacheline_aligned_in_smp; |
| 78 | |
| 79 | int node; |
| 80 | unsigned nr_workers; |
| 81 | unsigned max_workers; |
| 82 | atomic_t nr_running; |
| 83 | |
| 84 | struct io_wq_nulls_list free_list; |
| 85 | struct io_wq_nulls_list busy_list; |
| 86 | |
| 87 | struct io_wq *wq; |
| 88 | }; |
| 89 | |
| 90 | /* |
| 91 | * Per io_wq state |
| 92 | */ |
| 93 | struct io_wq { |
| 94 | struct io_wqe **wqes; |
| 95 | unsigned long state; |
| 96 | unsigned nr_wqes; |
| 97 | |
| 98 | struct task_struct *manager; |
| 99 | struct mm_struct *mm; |
| 100 | refcount_t refs; |
| 101 | struct completion done; |
| 102 | }; |
| 103 | |
| 104 | static void io_wq_free_worker(struct rcu_head *head) |
| 105 | { |
| 106 | struct io_worker *worker = container_of(head, struct io_worker, rcu); |
| 107 | |
| 108 | kfree(worker); |
| 109 | } |
| 110 | |
| 111 | static bool io_worker_get(struct io_worker *worker) |
| 112 | { |
| 113 | return refcount_inc_not_zero(&worker->ref); |
| 114 | } |
| 115 | |
| 116 | static void io_worker_release(struct io_worker *worker) |
| 117 | { |
| 118 | if (refcount_dec_and_test(&worker->ref)) |
| 119 | wake_up_process(worker->task); |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * Note: drops the wqe->lock if returning true! The caller must re-acquire |
| 124 | * the lock in that case. Some callers need to restart handling if this |
| 125 | * happens, so we can't just re-acquire the lock on behalf of the caller. |
| 126 | */ |
| 127 | static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker) |
| 128 | { |
| 129 | /* |
| 130 | * If we have an active mm, we need to drop the wq lock before unusing |
| 131 | * it. If we do, return true and let the caller retry the idle loop. |
| 132 | */ |
| 133 | if (worker->mm) { |
| 134 | __acquire(&wqe->lock); |
| 135 | spin_unlock_irq(&wqe->lock); |
| 136 | __set_current_state(TASK_RUNNING); |
| 137 | set_fs(KERNEL_DS); |
| 138 | unuse_mm(worker->mm); |
| 139 | mmput(worker->mm); |
| 140 | worker->mm = NULL; |
| 141 | return true; |
| 142 | } |
| 143 | |
| 144 | return false; |
| 145 | } |
| 146 | |
| 147 | static void io_worker_exit(struct io_worker *worker) |
| 148 | { |
| 149 | struct io_wqe *wqe = worker->wqe; |
| 150 | bool all_done = false; |
| 151 | |
| 152 | /* |
| 153 | * If we're not at zero, someone else is holding a brief reference |
| 154 | * to the worker. Wait for that to go away. |
| 155 | */ |
| 156 | set_current_state(TASK_INTERRUPTIBLE); |
| 157 | if (!refcount_dec_and_test(&worker->ref)) |
| 158 | schedule(); |
| 159 | __set_current_state(TASK_RUNNING); |
| 160 | |
| 161 | preempt_disable(); |
| 162 | current->flags &= ~PF_IO_WORKER; |
| 163 | if (worker->flags & IO_WORKER_F_RUNNING) |
| 164 | atomic_dec(&wqe->nr_running); |
| 165 | worker->flags = 0; |
| 166 | preempt_enable(); |
| 167 | |
| 168 | spin_lock_irq(&wqe->lock); |
| 169 | hlist_nulls_del_rcu(&worker->nulls_node); |
| 170 | if (__io_worker_unuse(wqe, worker)) { |
| 171 | __release(&wqe->lock); |
| 172 | spin_lock_irq(&wqe->lock); |
| 173 | } |
| 174 | wqe->nr_workers--; |
| 175 | all_done = !wqe->nr_workers; |
| 176 | spin_unlock_irq(&wqe->lock); |
| 177 | |
| 178 | /* all workers gone, wq exit can proceed */ |
| 179 | if (all_done && refcount_dec_and_test(&wqe->wq->refs)) |
| 180 | complete(&wqe->wq->done); |
| 181 | |
| 182 | call_rcu(&worker->rcu, io_wq_free_worker); |
| 183 | } |
| 184 | |
| 185 | static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker) |
| 186 | { |
| 187 | allow_kernel_signal(SIGINT); |
| 188 | |
| 189 | current->flags |= PF_IO_WORKER; |
| 190 | |
| 191 | worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING); |
| 192 | atomic_inc(&wqe->nr_running); |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Worker will start processing some work. Move it to the busy list, if |
| 197 | * it's currently on the freelist |
| 198 | */ |
| 199 | static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker, |
| 200 | struct io_wq_work *work) |
| 201 | __must_hold(wqe->lock) |
| 202 | { |
| 203 | if (worker->flags & IO_WORKER_F_FREE) { |
| 204 | worker->flags &= ~IO_WORKER_F_FREE; |
| 205 | hlist_nulls_del_init_rcu(&worker->nulls_node); |
| 206 | hlist_nulls_add_head_rcu(&worker->nulls_node, |
| 207 | &wqe->busy_list.head); |
| 208 | } |
| 209 | worker->cur_work = work; |
| 210 | } |
| 211 | |
| 212 | /* |
| 213 | * No work, worker going to sleep. Move to freelist, and unuse mm if we |
| 214 | * have one attached. Dropping the mm may potentially sleep, so we drop |
| 215 | * the lock in that case and return success. Since the caller has to |
| 216 | * retry the loop in that case (we changed task state), we don't regrab |
| 217 | * the lock if we return success. |
| 218 | */ |
| 219 | static bool __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker) |
| 220 | __must_hold(wqe->lock) |
| 221 | { |
| 222 | if (!(worker->flags & IO_WORKER_F_FREE)) { |
| 223 | worker->flags |= IO_WORKER_F_FREE; |
| 224 | hlist_nulls_del_init_rcu(&worker->nulls_node); |
| 225 | hlist_nulls_add_head_rcu(&worker->nulls_node, |
| 226 | &wqe->free_list.head); |
| 227 | } |
| 228 | |
| 229 | return __io_worker_unuse(wqe, worker); |
| 230 | } |
| 231 | |
| 232 | static struct io_wq_work *io_get_next_work(struct io_wqe *wqe, unsigned *hash) |
| 233 | __must_hold(wqe->lock) |
| 234 | { |
| 235 | struct io_wq_work *work; |
| 236 | |
| 237 | list_for_each_entry(work, &wqe->work_list, list) { |
| 238 | /* not hashed, can run anytime */ |
| 239 | if (!(work->flags & IO_WQ_WORK_HASHED)) { |
| 240 | list_del(&work->list); |
| 241 | return work; |
| 242 | } |
| 243 | |
| 244 | /* hashed, can run if not already running */ |
| 245 | *hash = work->flags >> IO_WQ_HASH_SHIFT; |
| 246 | if (!(wqe->hash_map & BIT_ULL(*hash))) { |
| 247 | wqe->hash_map |= BIT_ULL(*hash); |
| 248 | list_del(&work->list); |
| 249 | return work; |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | return NULL; |
| 254 | } |
| 255 | |
| 256 | static void io_worker_handle_work(struct io_worker *worker) |
| 257 | __releases(wqe->lock) |
| 258 | { |
| 259 | struct io_wq_work *work, *old_work; |
| 260 | struct io_wqe *wqe = worker->wqe; |
| 261 | struct io_wq *wq = wqe->wq; |
| 262 | |
| 263 | do { |
| 264 | unsigned hash = -1U; |
| 265 | |
| 266 | /* |
| 267 | * Signals are either sent to cancel specific work, or to just |
| 268 | * cancel all work items. For the former, ->cur_work must |
| 269 | * match. ->cur_work is NULL at this point, since we haven't |
| 270 | * assigned any work, so it's safe to flush signals for that |
| 271 | * case. For the latter case of cancelling all work, the caller |
| 272 | * wil have set IO_WQ_BIT_CANCEL. |
| 273 | */ |
| 274 | if (signal_pending(current)) |
| 275 | flush_signals(current); |
| 276 | |
| 277 | /* |
| 278 | * If we got some work, mark us as busy. If we didn't, but |
| 279 | * the list isn't empty, it means we stalled on hashed work. |
| 280 | * Mark us stalled so we don't keep looking for work when we |
| 281 | * can't make progress, any work completion or insertion will |
| 282 | * clear the stalled flag. |
| 283 | */ |
| 284 | work = io_get_next_work(wqe, &hash); |
| 285 | if (work) |
| 286 | __io_worker_busy(wqe, worker, work); |
| 287 | else if (!list_empty(&wqe->work_list)) |
| 288 | wqe->flags |= IO_WQE_FLAG_STALLED; |
| 289 | |
| 290 | spin_unlock_irq(&wqe->lock); |
| 291 | if (!work) |
| 292 | break; |
| 293 | next: |
| 294 | if ((work->flags & IO_WQ_WORK_NEEDS_USER) && !worker->mm && |
| 295 | wq->mm && mmget_not_zero(wq->mm)) { |
| 296 | use_mm(wq->mm); |
| 297 | set_fs(USER_DS); |
| 298 | worker->mm = wq->mm; |
| 299 | } |
| 300 | if (test_bit(IO_WQ_BIT_CANCEL, &wq->state)) |
| 301 | work->flags |= IO_WQ_WORK_CANCEL; |
| 302 | if (worker->mm) |
| 303 | work->flags |= IO_WQ_WORK_HAS_MM; |
| 304 | |
| 305 | old_work = work; |
| 306 | work->func(&work); |
| 307 | |
| 308 | spin_lock_irq(&wqe->lock); |
| 309 | worker->cur_work = NULL; |
| 310 | if (hash != -1U) { |
| 311 | wqe->hash_map &= ~BIT_ULL(hash); |
| 312 | wqe->flags &= ~IO_WQE_FLAG_STALLED; |
| 313 | } |
| 314 | if (work && work != old_work) { |
| 315 | spin_unlock_irq(&wqe->lock); |
| 316 | /* dependent work not hashed */ |
| 317 | hash = -1U; |
| 318 | goto next; |
| 319 | } |
| 320 | } while (1); |
| 321 | } |
| 322 | |
| 323 | static inline bool io_wqe_run_queue(struct io_wqe *wqe) |
| 324 | __must_hold(wqe->lock) |
| 325 | { |
| 326 | if (!list_empty_careful(&wqe->work_list) && |
| 327 | !(wqe->flags & IO_WQE_FLAG_STALLED)) |
| 328 | return true; |
| 329 | return false; |
| 330 | } |
| 331 | |
| 332 | static int io_wqe_worker(void *data) |
| 333 | { |
| 334 | struct io_worker *worker = data; |
| 335 | struct io_wqe *wqe = worker->wqe; |
| 336 | struct io_wq *wq = wqe->wq; |
| 337 | DEFINE_WAIT(wait); |
| 338 | |
| 339 | io_worker_start(wqe, worker); |
| 340 | |
| 341 | while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) { |
| 342 | prepare_to_wait(&worker->wait, &wait, TASK_INTERRUPTIBLE); |
| 343 | |
| 344 | spin_lock_irq(&wqe->lock); |
| 345 | if (io_wqe_run_queue(wqe)) { |
| 346 | __set_current_state(TASK_RUNNING); |
| 347 | io_worker_handle_work(worker); |
| 348 | continue; |
| 349 | } |
| 350 | /* drops the lock on success, retry */ |
| 351 | if (__io_worker_idle(wqe, worker)) { |
| 352 | __release(&wqe->lock); |
| 353 | continue; |
| 354 | } |
| 355 | spin_unlock_irq(&wqe->lock); |
| 356 | if (signal_pending(current)) |
| 357 | flush_signals(current); |
| 358 | if (schedule_timeout(WORKER_IDLE_TIMEOUT)) |
| 359 | continue; |
| 360 | /* timed out, exit unless we're the fixed worker */ |
| 361 | if (test_bit(IO_WQ_BIT_EXIT, &wq->state) || |
| 362 | !(worker->flags & IO_WORKER_F_FIXED)) |
| 363 | break; |
| 364 | } |
| 365 | |
| 366 | finish_wait(&worker->wait, &wait); |
| 367 | |
| 368 | if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) { |
| 369 | spin_lock_irq(&wqe->lock); |
| 370 | if (!list_empty(&wqe->work_list)) |
| 371 | io_worker_handle_work(worker); |
| 372 | else |
| 373 | spin_unlock_irq(&wqe->lock); |
| 374 | } |
| 375 | |
| 376 | io_worker_exit(worker); |
| 377 | return 0; |
| 378 | } |
| 379 | |
| 380 | /* |
| 381 | * Check head of free list for an available worker. If one isn't available, |
| 382 | * caller must wake up the wq manager to create one. |
| 383 | */ |
| 384 | static bool io_wqe_activate_free_worker(struct io_wqe *wqe) |
| 385 | __must_hold(RCU) |
| 386 | { |
| 387 | struct hlist_nulls_node *n; |
| 388 | struct io_worker *worker; |
| 389 | |
| 390 | n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list.head)); |
| 391 | if (is_a_nulls(n)) |
| 392 | return false; |
| 393 | |
| 394 | worker = hlist_nulls_entry(n, struct io_worker, nulls_node); |
| 395 | if (io_worker_get(worker)) { |
| 396 | wake_up(&worker->wait); |
| 397 | io_worker_release(worker); |
| 398 | return true; |
| 399 | } |
| 400 | |
| 401 | return false; |
| 402 | } |
| 403 | |
| 404 | /* |
| 405 | * We need a worker. If we find a free one, we're good. If not, and we're |
| 406 | * below the max number of workers, wake up the manager to create one. |
| 407 | */ |
| 408 | static void io_wqe_wake_worker(struct io_wqe *wqe) |
| 409 | { |
| 410 | bool ret; |
| 411 | |
| 412 | rcu_read_lock(); |
| 413 | ret = io_wqe_activate_free_worker(wqe); |
| 414 | rcu_read_unlock(); |
| 415 | |
| 416 | if (!ret && wqe->nr_workers < wqe->max_workers) |
| 417 | wake_up_process(wqe->wq->manager); |
| 418 | } |
| 419 | |
| 420 | /* |
| 421 | * Called when a worker is scheduled in. Mark us as currently running. |
| 422 | */ |
| 423 | void io_wq_worker_running(struct task_struct *tsk) |
| 424 | { |
| 425 | struct io_worker *worker = kthread_data(tsk); |
| 426 | struct io_wqe *wqe = worker->wqe; |
| 427 | |
| 428 | if (!(worker->flags & IO_WORKER_F_UP)) |
| 429 | return; |
| 430 | if (worker->flags & IO_WORKER_F_RUNNING) |
| 431 | return; |
| 432 | worker->flags |= IO_WORKER_F_RUNNING; |
| 433 | atomic_inc(&wqe->nr_running); |
| 434 | } |
| 435 | |
| 436 | /* |
| 437 | * Called when worker is going to sleep. If there are no workers currently |
| 438 | * running and we have work pending, wake up a free one or have the manager |
| 439 | * set one up. |
| 440 | */ |
| 441 | void io_wq_worker_sleeping(struct task_struct *tsk) |
| 442 | { |
| 443 | struct io_worker *worker = kthread_data(tsk); |
| 444 | struct io_wqe *wqe = worker->wqe; |
| 445 | |
| 446 | if (!(worker->flags & IO_WORKER_F_UP)) |
| 447 | return; |
| 448 | if (!(worker->flags & IO_WORKER_F_RUNNING)) |
| 449 | return; |
| 450 | |
| 451 | worker->flags &= ~IO_WORKER_F_RUNNING; |
| 452 | |
| 453 | spin_lock_irq(&wqe->lock); |
| 454 | if (atomic_dec_and_test(&wqe->nr_running) && io_wqe_run_queue(wqe)) |
| 455 | io_wqe_wake_worker(wqe); |
| 456 | spin_unlock_irq(&wqe->lock); |
| 457 | } |
| 458 | |
| 459 | static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe) |
| 460 | { |
| 461 | struct io_worker *worker; |
| 462 | |
| 463 | worker = kcalloc_node(1, sizeof(*worker), GFP_KERNEL, wqe->node); |
| 464 | if (!worker) |
| 465 | return; |
| 466 | |
| 467 | refcount_set(&worker->ref, 1); |
| 468 | worker->nulls_node.pprev = NULL; |
| 469 | init_waitqueue_head(&worker->wait); |
| 470 | worker->wqe = wqe; |
| 471 | |
| 472 | worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node, |
| 473 | "io_wqe_worker-%d", wqe->node); |
| 474 | if (IS_ERR(worker->task)) { |
| 475 | kfree(worker); |
| 476 | return; |
| 477 | } |
| 478 | |
| 479 | spin_lock_irq(&wqe->lock); |
| 480 | hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list.head); |
| 481 | worker->flags |= IO_WORKER_F_FREE; |
| 482 | if (!wqe->nr_workers) |
| 483 | worker->flags |= IO_WORKER_F_FIXED; |
| 484 | wqe->nr_workers++; |
| 485 | spin_unlock_irq(&wqe->lock); |
| 486 | |
| 487 | wake_up_process(worker->task); |
| 488 | } |
| 489 | |
| 490 | static inline bool io_wqe_need_new_worker(struct io_wqe *wqe) |
| 491 | __must_hold(wqe->lock) |
| 492 | { |
| 493 | if (!wqe->nr_workers) |
| 494 | return true; |
| 495 | if (hlist_nulls_empty(&wqe->free_list.head) && |
| 496 | wqe->nr_workers < wqe->max_workers && io_wqe_run_queue(wqe)) |
| 497 | return true; |
| 498 | |
| 499 | return false; |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * Manager thread. Tasked with creating new workers, if we need them. |
| 504 | */ |
| 505 | static int io_wq_manager(void *data) |
| 506 | { |
| 507 | struct io_wq *wq = data; |
| 508 | |
| 509 | while (!kthread_should_stop()) { |
| 510 | int i; |
| 511 | |
| 512 | for (i = 0; i < wq->nr_wqes; i++) { |
| 513 | struct io_wqe *wqe = wq->wqes[i]; |
| 514 | bool fork_worker = false; |
| 515 | |
| 516 | spin_lock_irq(&wqe->lock); |
| 517 | fork_worker = io_wqe_need_new_worker(wqe); |
| 518 | spin_unlock_irq(&wqe->lock); |
| 519 | if (fork_worker) |
| 520 | create_io_worker(wq, wqe); |
| 521 | } |
| 522 | set_current_state(TASK_INTERRUPTIBLE); |
| 523 | schedule_timeout(HZ); |
| 524 | } |
| 525 | |
| 526 | return 0; |
| 527 | } |
| 528 | |
| 529 | static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work) |
| 530 | { |
| 531 | unsigned long flags; |
| 532 | |
| 533 | spin_lock_irqsave(&wqe->lock, flags); |
| 534 | list_add_tail(&work->list, &wqe->work_list); |
| 535 | wqe->flags &= ~IO_WQE_FLAG_STALLED; |
| 536 | spin_unlock_irqrestore(&wqe->lock, flags); |
| 537 | |
| 538 | if (!atomic_read(&wqe->nr_running)) |
| 539 | io_wqe_wake_worker(wqe); |
| 540 | } |
| 541 | |
| 542 | void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work) |
| 543 | { |
| 544 | struct io_wqe *wqe = wq->wqes[numa_node_id()]; |
| 545 | |
| 546 | io_wqe_enqueue(wqe, work); |
| 547 | } |
| 548 | |
| 549 | /* |
| 550 | * Enqueue work, hashed by some key. Work items that hash to the same value |
| 551 | * will not be done in parallel. Used to limit concurrent writes, generally |
| 552 | * hashed by inode. |
| 553 | */ |
| 554 | void io_wq_enqueue_hashed(struct io_wq *wq, struct io_wq_work *work, void *val) |
| 555 | { |
| 556 | struct io_wqe *wqe = wq->wqes[numa_node_id()]; |
| 557 | unsigned bit; |
| 558 | |
| 559 | |
| 560 | bit = hash_ptr(val, IO_WQ_HASH_ORDER); |
| 561 | work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT)); |
| 562 | io_wqe_enqueue(wqe, work); |
| 563 | } |
| 564 | |
| 565 | static bool io_wqe_worker_send_sig(struct io_worker *worker, void *data) |
| 566 | { |
| 567 | send_sig(SIGINT, worker->task, 1); |
| 568 | return false; |
| 569 | } |
| 570 | |
| 571 | /* |
| 572 | * Iterate the passed in list and call the specific function for each |
| 573 | * worker that isn't exiting |
| 574 | */ |
| 575 | static bool io_wq_for_each_worker(struct io_wqe *wqe, |
| 576 | struct io_wq_nulls_list *list, |
| 577 | bool (*func)(struct io_worker *, void *), |
| 578 | void *data) |
| 579 | { |
| 580 | struct hlist_nulls_node *n; |
| 581 | struct io_worker *worker; |
| 582 | bool ret = false; |
| 583 | |
| 584 | restart: |
| 585 | hlist_nulls_for_each_entry_rcu(worker, n, &list->head, nulls_node) { |
| 586 | if (io_worker_get(worker)) { |
| 587 | ret = func(worker, data); |
| 588 | io_worker_release(worker); |
| 589 | if (ret) |
| 590 | break; |
| 591 | } |
| 592 | } |
| 593 | if (!ret && get_nulls_value(n) != list->nulls) |
| 594 | goto restart; |
| 595 | return ret; |
| 596 | } |
| 597 | |
| 598 | void io_wq_cancel_all(struct io_wq *wq) |
| 599 | { |
| 600 | int i; |
| 601 | |
| 602 | set_bit(IO_WQ_BIT_CANCEL, &wq->state); |
| 603 | |
| 604 | /* |
| 605 | * Browse both lists, as there's a gap between handing work off |
| 606 | * to a worker and the worker putting itself on the busy_list |
| 607 | */ |
| 608 | rcu_read_lock(); |
| 609 | for (i = 0; i < wq->nr_wqes; i++) { |
| 610 | struct io_wqe *wqe = wq->wqes[i]; |
| 611 | |
| 612 | io_wq_for_each_worker(wqe, &wqe->busy_list, |
| 613 | io_wqe_worker_send_sig, NULL); |
| 614 | io_wq_for_each_worker(wqe, &wqe->free_list, |
| 615 | io_wqe_worker_send_sig, NULL); |
| 616 | } |
| 617 | rcu_read_unlock(); |
| 618 | } |
| 619 | |
| 620 | static bool io_wq_worker_cancel(struct io_worker *worker, void *data) |
| 621 | { |
| 622 | struct io_wq_work *work = data; |
| 623 | |
| 624 | if (worker->cur_work == work) { |
| 625 | send_sig(SIGINT, worker->task, 1); |
| 626 | return true; |
| 627 | } |
| 628 | |
| 629 | return false; |
| 630 | } |
| 631 | |
| 632 | static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe, |
| 633 | struct io_wq_work *cwork) |
| 634 | { |
| 635 | struct io_wq_work *work; |
| 636 | bool found = false; |
| 637 | |
| 638 | cwork->flags |= IO_WQ_WORK_CANCEL; |
| 639 | |
| 640 | /* |
| 641 | * First check pending list, if we're lucky we can just remove it |
| 642 | * from there. CANCEL_OK means that the work is returned as-new, |
| 643 | * no completion will be posted for it. |
| 644 | */ |
| 645 | spin_lock_irq(&wqe->lock); |
| 646 | list_for_each_entry(work, &wqe->work_list, list) { |
| 647 | if (work == cwork) { |
| 648 | list_del(&work->list); |
| 649 | found = true; |
| 650 | break; |
| 651 | } |
| 652 | } |
| 653 | spin_unlock_irq(&wqe->lock); |
| 654 | |
| 655 | if (found) { |
| 656 | work->flags |= IO_WQ_WORK_CANCEL; |
| 657 | work->func(&work); |
| 658 | return IO_WQ_CANCEL_OK; |
| 659 | } |
| 660 | |
| 661 | /* |
| 662 | * Now check if a free (going busy) or busy worker has the work |
| 663 | * currently running. If we find it there, we'll return CANCEL_RUNNING |
| 664 | * as an indication that we attempte to signal cancellation. The |
| 665 | * completion will run normally in this case. |
| 666 | */ |
| 667 | rcu_read_lock(); |
| 668 | found = io_wq_for_each_worker(wqe, &wqe->free_list, io_wq_worker_cancel, |
| 669 | cwork); |
| 670 | if (found) |
| 671 | goto done; |
| 672 | |
| 673 | found = io_wq_for_each_worker(wqe, &wqe->busy_list, io_wq_worker_cancel, |
| 674 | cwork); |
| 675 | done: |
| 676 | rcu_read_unlock(); |
| 677 | return found ? IO_WQ_CANCEL_RUNNING : IO_WQ_CANCEL_NOTFOUND; |
| 678 | } |
| 679 | |
| 680 | enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork) |
| 681 | { |
| 682 | enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND; |
| 683 | int i; |
| 684 | |
| 685 | for (i = 0; i < wq->nr_wqes; i++) { |
| 686 | struct io_wqe *wqe = wq->wqes[i]; |
| 687 | |
| 688 | ret = io_wqe_cancel_work(wqe, cwork); |
| 689 | if (ret != IO_WQ_CANCEL_NOTFOUND) |
| 690 | break; |
| 691 | } |
| 692 | |
| 693 | return ret; |
| 694 | } |
| 695 | |
| 696 | struct io_wq_flush_data { |
| 697 | struct io_wq_work work; |
| 698 | struct completion done; |
| 699 | }; |
| 700 | |
| 701 | static void io_wq_flush_func(struct io_wq_work **workptr) |
| 702 | { |
| 703 | struct io_wq_work *work = *workptr; |
| 704 | struct io_wq_flush_data *data; |
| 705 | |
| 706 | data = container_of(work, struct io_wq_flush_data, work); |
| 707 | complete(&data->done); |
| 708 | } |
| 709 | |
| 710 | /* |
| 711 | * Doesn't wait for previously queued work to finish. When this completes, |
| 712 | * it just means that previously queued work was started. |
| 713 | */ |
| 714 | void io_wq_flush(struct io_wq *wq) |
| 715 | { |
| 716 | struct io_wq_flush_data data; |
| 717 | int i; |
| 718 | |
| 719 | for (i = 0; i < wq->nr_wqes; i++) { |
| 720 | struct io_wqe *wqe = wq->wqes[i]; |
| 721 | |
| 722 | init_completion(&data.done); |
| 723 | INIT_IO_WORK(&data.work, io_wq_flush_func); |
| 724 | io_wqe_enqueue(wqe, &data.work); |
| 725 | wait_for_completion(&data.done); |
| 726 | } |
| 727 | } |
| 728 | |
| 729 | struct io_wq *io_wq_create(unsigned concurrency, struct mm_struct *mm) |
| 730 | { |
| 731 | int ret = -ENOMEM, i, node; |
| 732 | struct io_wq *wq; |
| 733 | |
| 734 | wq = kcalloc(1, sizeof(*wq), GFP_KERNEL); |
| 735 | if (!wq) |
| 736 | return ERR_PTR(-ENOMEM); |
| 737 | |
| 738 | wq->nr_wqes = num_online_nodes(); |
| 739 | wq->wqes = kcalloc(wq->nr_wqes, sizeof(struct io_wqe *), GFP_KERNEL); |
| 740 | if (!wq->wqes) { |
| 741 | kfree(wq); |
| 742 | return ERR_PTR(-ENOMEM); |
| 743 | } |
| 744 | |
| 745 | i = 0; |
| 746 | refcount_set(&wq->refs, wq->nr_wqes); |
| 747 | for_each_online_node(node) { |
| 748 | struct io_wqe *wqe; |
| 749 | |
| 750 | wqe = kcalloc_node(1, sizeof(struct io_wqe), GFP_KERNEL, node); |
| 751 | if (!wqe) |
| 752 | break; |
| 753 | wq->wqes[i] = wqe; |
| 754 | wqe->node = node; |
| 755 | wqe->max_workers = concurrency; |
| 756 | wqe->node = node; |
| 757 | wqe->wq = wq; |
| 758 | spin_lock_init(&wqe->lock); |
| 759 | INIT_LIST_HEAD(&wqe->work_list); |
| 760 | INIT_HLIST_NULLS_HEAD(&wqe->free_list.head, 0); |
| 761 | wqe->free_list.nulls = 0; |
| 762 | INIT_HLIST_NULLS_HEAD(&wqe->busy_list.head, 1); |
| 763 | wqe->busy_list.nulls = 1; |
| 764 | atomic_set(&wqe->nr_running, 0); |
| 765 | |
| 766 | i++; |
| 767 | } |
| 768 | |
| 769 | init_completion(&wq->done); |
| 770 | |
| 771 | if (i != wq->nr_wqes) |
| 772 | goto err; |
| 773 | |
| 774 | /* caller must have already done mmgrab() on this mm */ |
| 775 | wq->mm = mm; |
| 776 | |
| 777 | wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager"); |
| 778 | if (!IS_ERR(wq->manager)) { |
| 779 | wake_up_process(wq->manager); |
| 780 | return wq; |
| 781 | } |
| 782 | |
| 783 | ret = PTR_ERR(wq->manager); |
| 784 | wq->manager = NULL; |
| 785 | err: |
| 786 | complete(&wq->done); |
| 787 | io_wq_destroy(wq); |
| 788 | return ERR_PTR(ret); |
| 789 | } |
| 790 | |
| 791 | static bool io_wq_worker_wake(struct io_worker *worker, void *data) |
| 792 | { |
| 793 | wake_up_process(worker->task); |
| 794 | return false; |
| 795 | } |
| 796 | |
| 797 | void io_wq_destroy(struct io_wq *wq) |
| 798 | { |
| 799 | int i; |
| 800 | |
| 801 | if (wq->manager) { |
| 802 | set_bit(IO_WQ_BIT_EXIT, &wq->state); |
| 803 | kthread_stop(wq->manager); |
| 804 | } |
| 805 | |
| 806 | rcu_read_lock(); |
| 807 | for (i = 0; i < wq->nr_wqes; i++) { |
| 808 | struct io_wqe *wqe = wq->wqes[i]; |
| 809 | |
| 810 | if (!wqe) |
| 811 | continue; |
| 812 | io_wq_for_each_worker(wqe, &wqe->free_list, io_wq_worker_wake, |
| 813 | NULL); |
| 814 | io_wq_for_each_worker(wqe, &wqe->busy_list, io_wq_worker_wake, |
| 815 | NULL); |
| 816 | } |
| 817 | rcu_read_unlock(); |
| 818 | |
| 819 | wait_for_completion(&wq->done); |
| 820 | |
| 821 | for (i = 0; i < wq->nr_wqes; i++) |
| 822 | kfree(wq->wqes[i]); |
| 823 | kfree(wq->wqes); |
| 824 | kfree(wq); |
| 825 | } |