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| | 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 | } |