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1// SPDX-License-Identifier: GPL-2.02#include <linux/kernel.h>3#include <linux/errno.h>4#include <linux/fs.h>5#include <linux/file.h>6#include <linux/mm.h>7#include <linux/slab.h>8#include <linux/poll.h>9#include <linux/hashtable.h>10#include <linux/io_uring.h>11 12#include <trace/events/io_uring.h>13 14#include <uapi/linux/io_uring.h>15 16#include "io_uring.h"17#include "alloc_cache.h"18#include "refs.h"19#include "napi.h"20#include "opdef.h"21#include "kbuf.h"22#include "poll.h"23#include "cancel.h"24 25struct io_poll_update {26 struct file *file;27 u64 old_user_data;28 u64 new_user_data;29 __poll_t events;30 bool update_events;31 bool update_user_data;32};33 34struct io_poll_table {35 struct poll_table_struct pt;36 struct io_kiocb *req;37 int nr_entries;38 int error;39 bool owning;40 /* output value, set only if arm poll returns >0 */41 __poll_t result_mask;42};43 44#define IO_POLL_CANCEL_FLAG BIT(31)45#define IO_POLL_RETRY_FLAG BIT(30)46#define IO_POLL_REF_MASK GENMASK(29, 0)47 48/*49 * We usually have 1-2 refs taken, 128 is more than enough and we want to50 * maximise the margin between this amount and the moment when it overflows.51 */52#define IO_POLL_REF_BIAS 12853 54#define IO_WQE_F_DOUBLE 155 56static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,57 void *key);58 59static inline struct io_kiocb *wqe_to_req(struct wait_queue_entry *wqe)60{61 unsigned long priv = (unsigned long)wqe->private;62 63 return (struct io_kiocb *)(priv & ~IO_WQE_F_DOUBLE);64}65 66static inline bool wqe_is_double(struct wait_queue_entry *wqe)67{68 unsigned long priv = (unsigned long)wqe->private;69 70 return priv & IO_WQE_F_DOUBLE;71}72 73static bool io_poll_get_ownership_slowpath(struct io_kiocb *req)74{75 int v;76 77 /*78 * poll_refs are already elevated and we don't have much hope for79 * grabbing the ownership. Instead of incrementing set a retry flag80 * to notify the loop that there might have been some change.81 */82 v = atomic_fetch_or(IO_POLL_RETRY_FLAG, &req->poll_refs);83 if (v & IO_POLL_REF_MASK)84 return false;85 return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);86}87 88/*89 * If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can90 * bump it and acquire ownership. It's disallowed to modify requests while not91 * owning it, that prevents from races for enqueueing task_work's and b/w92 * arming poll and wakeups.93 */94static inline bool io_poll_get_ownership(struct io_kiocb *req)95{96 if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))97 return io_poll_get_ownership_slowpath(req);98 return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);99}100 101static void io_poll_mark_cancelled(struct io_kiocb *req)102{103 atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);104}105 106static struct io_poll *io_poll_get_double(struct io_kiocb *req)107{108 /* pure poll stashes this in ->async_data, poll driven retry elsewhere */109 if (req->opcode == IORING_OP_POLL_ADD)110 return req->async_data;111 return req->apoll->double_poll;112}113 114static struct io_poll *io_poll_get_single(struct io_kiocb *req)115{116 if (req->opcode == IORING_OP_POLL_ADD)117 return io_kiocb_to_cmd(req, struct io_poll);118 return &req->apoll->poll;119}120 121static void io_poll_req_insert(struct io_kiocb *req)122{123 struct io_hash_table *table = &req->ctx->cancel_table;124 u32 index = hash_long(req->cqe.user_data, table->hash_bits);125 struct io_hash_bucket *hb = &table->hbs[index];126 127 spin_lock(&hb->lock);128 hlist_add_head(&req->hash_node, &hb->list);129 spin_unlock(&hb->lock);130}131 132static void io_poll_req_delete(struct io_kiocb *req, struct io_ring_ctx *ctx)133{134 struct io_hash_table *table = &req->ctx->cancel_table;135 u32 index = hash_long(req->cqe.user_data, table->hash_bits);136 spinlock_t *lock = &table->hbs[index].lock;137 138 spin_lock(lock);139 hash_del(&req->hash_node);140 spin_unlock(lock);141}142 143static void io_poll_req_insert_locked(struct io_kiocb *req)144{145 struct io_hash_table *table = &req->ctx->cancel_table_locked;146 u32 index = hash_long(req->cqe.user_data, table->hash_bits);147 148 lockdep_assert_held(&req->ctx->uring_lock);149 150 hlist_add_head(&req->hash_node, &table->hbs[index].list);151}152 153static void io_poll_tw_hash_eject(struct io_kiocb *req, struct io_tw_state *ts)154{155 struct io_ring_ctx *ctx = req->ctx;156 157 if (req->flags & REQ_F_HASH_LOCKED) {158 /*159 * ->cancel_table_locked is protected by ->uring_lock in160 * contrast to per bucket spinlocks. Likely, tctx_task_work()161 * already grabbed the mutex for us, but there is a chance it162 * failed.163 */164 io_tw_lock(ctx, ts);165 hash_del(&req->hash_node);166 req->flags &= ~REQ_F_HASH_LOCKED;167 } else {168 io_poll_req_delete(req, ctx);169 }170}171 172static void io_init_poll_iocb(struct io_poll *poll, __poll_t events)173{174 poll->head = NULL;175#define IO_POLL_UNMASK (EPOLLERR|EPOLLHUP|EPOLLNVAL|EPOLLRDHUP)176 /* mask in events that we always want/need */177 poll->events = events | IO_POLL_UNMASK;178 INIT_LIST_HEAD(&poll->wait.entry);179 init_waitqueue_func_entry(&poll->wait, io_poll_wake);180}181 182static inline void io_poll_remove_entry(struct io_poll *poll)183{184 struct wait_queue_head *head = smp_load_acquire(&poll->head);185 186 if (head) {187 spin_lock_irq(&head->lock);188 list_del_init(&poll->wait.entry);189 poll->head = NULL;190 spin_unlock_irq(&head->lock);191 }192}193 194static void io_poll_remove_entries(struct io_kiocb *req)195{196 /*197 * Nothing to do if neither of those flags are set. Avoid dipping198 * into the poll/apoll/double cachelines if we can.199 */200 if (!(req->flags & (REQ_F_SINGLE_POLL | REQ_F_DOUBLE_POLL)))201 return;202 203 /*204 * While we hold the waitqueue lock and the waitqueue is nonempty,205 * wake_up_pollfree() will wait for us. However, taking the waitqueue206 * lock in the first place can race with the waitqueue being freed.207 *208 * We solve this as eventpoll does: by taking advantage of the fact that209 * all users of wake_up_pollfree() will RCU-delay the actual free. If210 * we enter rcu_read_lock() and see that the pointer to the queue is211 * non-NULL, we can then lock it without the memory being freed out from212 * under us.213 *214 * Keep holding rcu_read_lock() as long as we hold the queue lock, in215 * case the caller deletes the entry from the queue, leaving it empty.216 * In that case, only RCU prevents the queue memory from being freed.217 */218 rcu_read_lock();219 if (req->flags & REQ_F_SINGLE_POLL)220 io_poll_remove_entry(io_poll_get_single(req));221 if (req->flags & REQ_F_DOUBLE_POLL)222 io_poll_remove_entry(io_poll_get_double(req));223 rcu_read_unlock();224}225 226enum {227 IOU_POLL_DONE = 0,228 IOU_POLL_NO_ACTION = 1,229 IOU_POLL_REMOVE_POLL_USE_RES = 2,230 IOU_POLL_REISSUE = 3,231 IOU_POLL_REQUEUE = 4,232};233 234static HWJS_SUSPENDS void __io_poll_execute(struct io_kiocb *req, int mask)235{236 unsigned flags = 0;237 238 io_req_set_res(req, mask, 0);239 req->io_task_work.func = io_poll_task_func;240 241 trace_io_uring_task_add(req, mask);242 243 if (!(req->flags & REQ_F_POLL_NO_LAZY))244 flags = IOU_F_TWQ_LAZY_WAKE;245 __io_req_task_work_add(req, flags);246}247 248static HWJS_SUSPENDS inline void io_poll_execute(struct io_kiocb *req, int res)249{250 if (io_poll_get_ownership(req))251 __io_poll_execute(req, res);252}253 254/*255 * All poll tw should go through this. Checks for poll events, manages256 * references, does rewait, etc.257 *258 * Returns a negative error on failure. IOU_POLL_NO_ACTION when no action259 * require, which is either spurious wakeup or multishot CQE is served.260 * IOU_POLL_DONE when it's done with the request, then the mask is stored in261 * req->cqe.res. IOU_POLL_REMOVE_POLL_USE_RES indicates to remove multishot262 * poll and that the result is stored in req->cqe.263 */264static HWJS_SUSPENDS int io_poll_check_events(struct io_kiocb *req, struct io_tw_state *ts)265{266 int v;267 268 /* req->task == current here, checking PF_EXITING is safe */269 if (unlikely(req->task->flags & PF_EXITING))270 return -ECANCELED;271 272 do {273 v = atomic_read(&req->poll_refs);274 275 if (unlikely(v != 1)) {276 /* tw should be the owner and so have some refs */277 if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK)))278 return IOU_POLL_NO_ACTION;279 if (v & IO_POLL_CANCEL_FLAG)280 return -ECANCELED;281 /*282 * cqe.res contains only events of the first wake up283 * and all others are to be lost. Redo vfs_poll() to get284 * up to date state.285 */286 if ((v & IO_POLL_REF_MASK) != 1)287 req->cqe.res = 0;288 289 if (v & IO_POLL_RETRY_FLAG) {290 req->cqe.res = 0;291 /*292 * We won't find new events that came in between293 * vfs_poll and the ref put unless we clear the294 * flag in advance.295 */296 atomic_andnot(IO_POLL_RETRY_FLAG, &req->poll_refs);297 v &= ~IO_POLL_RETRY_FLAG;298 }299 }300 301 /* the mask was stashed in __io_poll_execute */302 if (!req->cqe.res) {303 struct poll_table_struct pt = { ._key = req->apoll_events };304 req->cqe.res = vfs_poll(req->file, &pt) & req->apoll_events;305 /*306 * We got woken with a mask, but someone else got to307 * it first. The above vfs_poll() doesn't add us back308 * to the waitqueue, so if we get nothing back, we309 * should be safe and attempt a reissue.310 */311 if (unlikely(!req->cqe.res)) {312 /* Multishot armed need not reissue */313 if (!(req->apoll_events & EPOLLONESHOT))314 continue;315 return IOU_POLL_REISSUE;316 }317 }318 if (req->apoll_events & EPOLLONESHOT)319 return IOU_POLL_DONE;320 321 /* multishot, just fill a CQE and proceed */322 if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {323 __poll_t mask = mangle_poll(req->cqe.res &324 req->apoll_events);325 326 if (!io_req_post_cqe(req, mask, IORING_CQE_F_MORE)) {327 io_req_set_res(req, mask, 0);328 return IOU_POLL_REMOVE_POLL_USE_RES;329 }330 } else {331 int ret = io_poll_issue(req, ts);332 if (ret == IOU_STOP_MULTISHOT)333 return IOU_POLL_REMOVE_POLL_USE_RES;334 else if (ret == IOU_REQUEUE)335 return IOU_POLL_REQUEUE;336 if (ret < 0)337 return ret;338 }339 340 /* force the next iteration to vfs_poll() */341 req->cqe.res = 0;342 343 /*344 * Release all references, retry if someone tried to restart345 * task_work while we were executing it.346 */347 v &= IO_POLL_REF_MASK;348 } while (atomic_sub_return(v, &req->poll_refs) & IO_POLL_REF_MASK);349 350 io_napi_add(req);351 return IOU_POLL_NO_ACTION;352}353 354void io_poll_task_func(struct io_kiocb *req, struct io_tw_state *ts)355{356 int ret;357 358 ret = io_poll_check_events(req, ts);359 if (ret == IOU_POLL_NO_ACTION) {360 return;361 } else if (ret == IOU_POLL_REQUEUE) {362 __io_poll_execute(req, 0);363 return;364 }365 io_poll_remove_entries(req);366 io_poll_tw_hash_eject(req, ts);367 368 if (req->opcode == IORING_OP_POLL_ADD) {369 if (ret == IOU_POLL_DONE) {370 struct io_poll *poll;371 372 poll = io_kiocb_to_cmd(req, struct io_poll);373 req->cqe.res = mangle_poll(req->cqe.res & poll->events);374 } else if (ret == IOU_POLL_REISSUE) {375 io_req_task_submit(req, ts);376 return;377 } else if (ret != IOU_POLL_REMOVE_POLL_USE_RES) {378 req->cqe.res = ret;379 req_set_fail(req);380 }381 382 io_req_set_res(req, req->cqe.res, 0);383 io_req_task_complete(req, ts);384 } else {385 io_tw_lock(req->ctx, ts);386 387 if (ret == IOU_POLL_REMOVE_POLL_USE_RES)388 io_req_task_complete(req, ts);389 else if (ret == IOU_POLL_DONE || ret == IOU_POLL_REISSUE)390 io_req_task_submit(req, ts);391 else392 io_req_defer_failed(req, ret);393 }394}395 396static HWJS_SUSPENDS void io_poll_cancel_req(struct io_kiocb *req)397{398 io_poll_mark_cancelled(req);399 /* kick tw, which should complete the request */400 io_poll_execute(req, 0);401}402 403#define IO_ASYNC_POLL_COMMON (EPOLLONESHOT | EPOLLPRI)404 405static __cold int io_pollfree_wake(struct io_kiocb *req, struct io_poll *poll)406{407 io_poll_mark_cancelled(req);408 /* we have to kick tw in case it's not already */409 io_poll_execute(req, 0);410 411 /*412 * If the waitqueue is being freed early but someone is already413 * holds ownership over it, we have to tear down the request as414 * best we can. That means immediately removing the request from415 * its waitqueue and preventing all further accesses to the416 * waitqueue via the request.417 */418 list_del_init(&poll->wait.entry);419 420 /*421 * Careful: this *must* be the last step, since as soon422 * as req->head is NULL'ed out, the request can be423 * completed and freed, since aio_poll_complete_work()424 * will no longer need to take the waitqueue lock.425 */426 smp_store_release(&poll->head, NULL);427 return 1;428}429 430static HWJS_SUSPENDS int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,431 void *key)432{433 struct io_kiocb *req = wqe_to_req(wait);434 struct io_poll *poll = container_of(wait, struct io_poll, wait);435 __poll_t mask = key_to_poll(key);436 437 if (unlikely(mask & POLLFREE))438 return io_pollfree_wake(req, poll);439 440 /* for instances that support it check for an event match first */441 if (mask && !(mask & (poll->events & ~IO_ASYNC_POLL_COMMON)))442 return 0;443 444 if (io_poll_get_ownership(req)) {445 /*446 * If we trigger a multishot poll off our own wakeup path,447 * disable multishot as there is a circular dependency between448 * CQ posting and triggering the event.449 */450 if (mask & EPOLL_URING_WAKE)451 poll->events |= EPOLLONESHOT;452 453 /* optional, saves extra locking for removal in tw handler */454 if (mask && poll->events & EPOLLONESHOT) {455 list_del_init(&poll->wait.entry);456 poll->head = NULL;457 if (wqe_is_double(wait))458 req->flags &= ~REQ_F_DOUBLE_POLL;459 else460 req->flags &= ~REQ_F_SINGLE_POLL;461 }462 __io_poll_execute(req, mask);463 }464 return 1;465}466 467/* fails only when polling is already completing by the first entry */468static bool io_poll_double_prepare(struct io_kiocb *req)469{470 struct wait_queue_head *head;471 struct io_poll *poll = io_poll_get_single(req);472 473 /* head is RCU protected, see io_poll_remove_entries() comments */474 rcu_read_lock();475 head = smp_load_acquire(&poll->head);476 /*477 * poll arm might not hold ownership and so race for req->flags with478 * io_poll_wake(). There is only one poll entry queued, serialise with479 * it by taking its head lock. As we're still arming the tw hanlder480 * is not going to be run, so there are no races with it.481 */482 if (head) {483 spin_lock_irq(&head->lock);484 req->flags |= REQ_F_DOUBLE_POLL;485 if (req->opcode == IORING_OP_POLL_ADD)486 req->flags |= REQ_F_ASYNC_DATA;487 spin_unlock_irq(&head->lock);488 }489 rcu_read_unlock();490 return !!head;491}492 493static void __io_queue_proc(struct io_poll *poll, struct io_poll_table *pt,494 struct wait_queue_head *head,495 struct io_poll **poll_ptr)496{497 struct io_kiocb *req = pt->req;498 unsigned long wqe_private = (unsigned long) req;499 500 /*501 * The file being polled uses multiple waitqueues for poll handling502 * (e.g. one for read, one for write). Setup a separate io_poll503 * if this happens.504 */505 if (unlikely(pt->nr_entries)) {506 struct io_poll *first = poll;507 508 /* double add on the same waitqueue head, ignore */509 if (first->head == head)510 return;511 /* already have a 2nd entry, fail a third attempt */512 if (*poll_ptr) {513 if ((*poll_ptr)->head == head)514 return;515 pt->error = -EINVAL;516 return;517 }518 519 poll = kmalloc(sizeof(*poll), GFP_ATOMIC);520 if (!poll) {521 pt->error = -ENOMEM;522 return;523 }524 525 /* mark as double wq entry */526 wqe_private |= IO_WQE_F_DOUBLE;527 io_init_poll_iocb(poll, first->events);528 if (!io_poll_double_prepare(req)) {529 /* the request is completing, just back off */530 kfree(poll);531 return;532 }533 *poll_ptr = poll;534 } else {535 /* fine to modify, there is no poll queued to race with us */536 req->flags |= REQ_F_SINGLE_POLL;537 }538 539 pt->nr_entries++;540 poll->head = head;541 poll->wait.private = (void *) wqe_private;542 543 if (poll->events & EPOLLEXCLUSIVE) {544 add_wait_queue_exclusive(head, &poll->wait);545 } else {546 add_wait_queue(head, &poll->wait);547 }548}549 550static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,551 struct poll_table_struct *p)552{553 struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);554 struct io_poll *poll = io_kiocb_to_cmd(pt->req, struct io_poll);555 556 __io_queue_proc(poll, pt, head,557 (struct io_poll **) &pt->req->async_data);558}559 560static bool io_poll_can_finish_inline(struct io_kiocb *req,561 struct io_poll_table *pt)562{563 return pt->owning || io_poll_get_ownership(req);564}565 566static void io_poll_add_hash(struct io_kiocb *req)567{568 if (req->flags & REQ_F_HASH_LOCKED)569 io_poll_req_insert_locked(req);570 else571 io_poll_req_insert(req);572}573 574/*575 * Returns 0 when it's handed over for polling. The caller owns the requests if576 * it returns non-zero, but otherwise should not touch it. Negative values577 * contain an error code. When the result is >0, the polling has completed578 * inline and ipt.result_mask is set to the mask.579 */580static HWJS_SUSPENDS int __io_arm_poll_handler(struct io_kiocb *req,581 struct io_poll *poll,582 struct io_poll_table *ipt, __poll_t mask,583 unsigned issue_flags)584{585 INIT_HLIST_NODE(&req->hash_node);586 io_init_poll_iocb(poll, mask);587 poll->file = req->file;588 req->apoll_events = poll->events;589 590 ipt->pt._key = mask;591 ipt->req = req;592 ipt->error = 0;593 ipt->nr_entries = 0;594 /*595 * Polling is either completed here or via task_work, so if we're in the596 * task context we're naturally serialised with tw by merit of running597 * the same task. When it's io-wq, take the ownership to prevent tw598 * from running. However, when we're in the task context, skip taking599 * it as an optimisation.600 *601 * Note: even though the request won't be completed/freed, without602 * ownership we still can race with io_poll_wake().603 * io_poll_can_finish_inline() tries to deal with that.604 */605 ipt->owning = issue_flags & IO_URING_F_UNLOCKED;606 atomic_set(&req->poll_refs, (int)ipt->owning);607 608 /* io-wq doesn't hold uring_lock */609 if (issue_flags & IO_URING_F_UNLOCKED)610 req->flags &= ~REQ_F_HASH_LOCKED;611 612 613 /*614 * Exclusive waits may only wake a limited amount of entries615 * rather than all of them, this may interfere with lazy616 * wake if someone does wait(events > 1). Ensure we don't do617 * lazy wake for those, as we need to process each one as they618 * come in.619 */620 if (poll->events & EPOLLEXCLUSIVE)621 req->flags |= REQ_F_POLL_NO_LAZY;622 623 mask = vfs_poll(req->file, &ipt->pt) & poll->events;624 625 if (unlikely(ipt->error || !ipt->nr_entries)) {626 io_poll_remove_entries(req);627 628 if (!io_poll_can_finish_inline(req, ipt)) {629 io_poll_mark_cancelled(req);630 return 0;631 } else if (mask && (poll->events & EPOLLET)) {632 ipt->result_mask = mask;633 return 1;634 }635 return ipt->error ?: -EINVAL;636 }637 638 if (mask &&639 ((poll->events & (EPOLLET|EPOLLONESHOT)) == (EPOLLET|EPOLLONESHOT))) {640 if (!io_poll_can_finish_inline(req, ipt)) {641 io_poll_add_hash(req);642 return 0;643 }644 io_poll_remove_entries(req);645 ipt->result_mask = mask;646 /* no one else has access to the req, forget about the ref */647 return 1;648 }649 650 io_poll_add_hash(req);651 652 if (mask && (poll->events & EPOLLET) &&653 io_poll_can_finish_inline(req, ipt)) {654 __io_poll_execute(req, mask);655 return 0;656 }657 io_napi_add(req);658 659 if (ipt->owning) {660 /*661 * Try to release ownership. If we see a change of state, e.g.662 * poll was waken up, queue up a tw, it'll deal with it.663 */664 if (atomic_cmpxchg(&req->poll_refs, 1, 0) != 1)665 __io_poll_execute(req, 0);666 }667 return 0;668}669 670static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,671 struct poll_table_struct *p)672{673 struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);674 struct async_poll *apoll = pt->req->apoll;675 676 __io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);677}678 679/*680 * We can't reliably detect loops in repeated poll triggers and issue681 * subsequently failing. But rather than fail these immediately, allow a682 * certain amount of retries before we give up. Given that this condition683 * should _rarely_ trigger even once, we should be fine with a larger value.684 */685#define APOLL_MAX_RETRY 128686 687static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,688 unsigned issue_flags)689{690 struct io_ring_ctx *ctx = req->ctx;691 struct async_poll *apoll;692 693 if (req->flags & REQ_F_POLLED) {694 apoll = req->apoll;695 kfree(apoll->double_poll);696 } else if (!(issue_flags & IO_URING_F_UNLOCKED)) {697 apoll = io_alloc_cache_get(&ctx->apoll_cache);698 if (!apoll)699 goto alloc_apoll;700 apoll->poll.retries = APOLL_MAX_RETRY;701 } else {702alloc_apoll:703 apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);704 if (unlikely(!apoll))705 return NULL;706 apoll->poll.retries = APOLL_MAX_RETRY;707 }708 apoll->double_poll = NULL;709 req->apoll = apoll;710 if (unlikely(!--apoll->poll.retries))711 return NULL;712 return apoll;713}714 715int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)716{717 const struct io_issue_def *def = &io_issue_defs[req->opcode];718 struct async_poll *apoll;719 struct io_poll_table ipt;720 __poll_t mask = POLLPRI | POLLERR | EPOLLET;721 int ret;722 723 /*724 * apoll requests already grab the mutex to complete in the tw handler,725 * so removal from the mutex-backed hash is free, use it by default.726 */727 req->flags |= REQ_F_HASH_LOCKED;728 729 if (!def->pollin && !def->pollout)730 return IO_APOLL_ABORTED;731 if (!io_file_can_poll(req))732 return IO_APOLL_ABORTED;733 if (!(req->flags & REQ_F_APOLL_MULTISHOT))734 mask |= EPOLLONESHOT;735 736 if (def->pollin) {737 mask |= EPOLLIN | EPOLLRDNORM;738 739 /* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */740 if (req->flags & REQ_F_CLEAR_POLLIN)741 mask &= ~EPOLLIN;742 } else {743 mask |= EPOLLOUT | EPOLLWRNORM;744 }745 if (def->poll_exclusive)746 mask |= EPOLLEXCLUSIVE;747 748 apoll = io_req_alloc_apoll(req, issue_flags);749 if (!apoll)750 return IO_APOLL_ABORTED;751 req->flags &= ~(REQ_F_SINGLE_POLL | REQ_F_DOUBLE_POLL);752 req->flags |= REQ_F_POLLED;753 ipt.pt._qproc = io_async_queue_proc;754 755 io_kbuf_recycle(req, issue_flags);756 757 ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask, issue_flags);758 if (ret)759 return ret > 0 ? IO_APOLL_READY : IO_APOLL_ABORTED;760 trace_io_uring_poll_arm(req, mask, apoll->poll.events);761 return IO_APOLL_OK;762}763 764static HWJS_SUSPENDS __cold bool io_poll_remove_all_table(struct task_struct *tsk,765 struct io_hash_table *table,766 bool cancel_all)767{768 unsigned nr_buckets = 1U << table->hash_bits;769 struct hlist_node *tmp;770 struct io_kiocb *req;771 bool found = false;772 int i;773 774 for (i = 0; i < nr_buckets; i++) {775 struct io_hash_bucket *hb = &table->hbs[i];776 777 spin_lock(&hb->lock);778 hlist_for_each_entry_safe(req, tmp, &hb->list, hash_node) {779 if (io_match_task_safe(req, tsk, cancel_all)) {780 hlist_del_init(&req->hash_node);781 io_poll_cancel_req(req);782 found = true;783 }784 }785 spin_unlock(&hb->lock);786 }787 return found;788}789 790/*791 * Returns true if we found and killed one or more poll requests792 */793__cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,794 bool cancel_all)795 __must_hold(&ctx->uring_lock)796{797 bool ret;798 799 ret = io_poll_remove_all_table(tsk, &ctx->cancel_table, cancel_all);800 ret |= io_poll_remove_all_table(tsk, &ctx->cancel_table_locked, cancel_all);801 return ret;802}803 804static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,805 struct io_cancel_data *cd,806 struct io_hash_table *table,807 struct io_hash_bucket **out_bucket)808{809 struct io_kiocb *req;810 u32 index = hash_long(cd->data, table->hash_bits);811 struct io_hash_bucket *hb = &table->hbs[index];812 813 *out_bucket = NULL;814 815 spin_lock(&hb->lock);816 hlist_for_each_entry(req, &hb->list, hash_node) {817 if (cd->data != req->cqe.user_data)818 continue;819 if (poll_only && req->opcode != IORING_OP_POLL_ADD)820 continue;821 if (cd->flags & IORING_ASYNC_CANCEL_ALL) {822 if (io_cancel_match_sequence(req, cd->seq))823 continue;824 }825 *out_bucket = hb;826 return req;827 }828 spin_unlock(&hb->lock);829 return NULL;830}831 832static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,833 struct io_cancel_data *cd,834 struct io_hash_table *table,835 struct io_hash_bucket **out_bucket)836{837 unsigned nr_buckets = 1U << table->hash_bits;838 struct io_kiocb *req;839 int i;840 841 *out_bucket = NULL;842 843 for (i = 0; i < nr_buckets; i++) {844 struct io_hash_bucket *hb = &table->hbs[i];845 846 spin_lock(&hb->lock);847 hlist_for_each_entry(req, &hb->list, hash_node) {848 if (io_cancel_req_match(req, cd)) {849 *out_bucket = hb;850 return req;851 }852 }853 spin_unlock(&hb->lock);854 }855 return NULL;856}857 858static int io_poll_disarm(struct io_kiocb *req)859{860 if (!req)861 return -ENOENT;862 if (!io_poll_get_ownership(req))863 return -EALREADY;864 io_poll_remove_entries(req);865 hash_del(&req->hash_node);866 return 0;867}868 869static HWJS_SUSPENDS int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,870 struct io_hash_table *table)871{872 struct io_hash_bucket *bucket;873 struct io_kiocb *req;874 875 if (cd->flags & (IORING_ASYNC_CANCEL_FD | IORING_ASYNC_CANCEL_OP |876 IORING_ASYNC_CANCEL_ANY))877 req = io_poll_file_find(ctx, cd, table, &bucket);878 else879 req = io_poll_find(ctx, false, cd, table, &bucket);880 881 if (req)882 io_poll_cancel_req(req);883 if (bucket)884 spin_unlock(&bucket->lock);885 return req ? 0 : -ENOENT;886}887 888int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,889 unsigned issue_flags)890{891 int ret;892 893 ret = __io_poll_cancel(ctx, cd, &ctx->cancel_table);894 if (ret != -ENOENT)895 return ret;896 897 io_ring_submit_lock(ctx, issue_flags);898 ret = __io_poll_cancel(ctx, cd, &ctx->cancel_table_locked);899 io_ring_submit_unlock(ctx, issue_flags);900 return ret;901}902 903static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe,904 unsigned int flags)905{906 u32 events;907 908 events = READ_ONCE(sqe->poll32_events);909#ifdef __BIG_ENDIAN910 events = swahw32(events);911#endif912 if (!(flags & IORING_POLL_ADD_MULTI))913 events |= EPOLLONESHOT;914 if (!(flags & IORING_POLL_ADD_LEVEL))915 events |= EPOLLET;916 return demangle_poll(events) |917 (events & (EPOLLEXCLUSIVE|EPOLLONESHOT|EPOLLET));918}919 920int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)921{922 struct io_poll_update *upd = io_kiocb_to_cmd(req, struct io_poll_update);923 u32 flags;924 925 if (sqe->buf_index || sqe->splice_fd_in)926 return -EINVAL;927 flags = READ_ONCE(sqe->len);928 if (flags & ~(IORING_POLL_UPDATE_EVENTS | IORING_POLL_UPDATE_USER_DATA |929 IORING_POLL_ADD_MULTI))930 return -EINVAL;931 /* meaningless without update */932 if (flags == IORING_POLL_ADD_MULTI)933 return -EINVAL;934 935 upd->old_user_data = READ_ONCE(sqe->addr);936 upd->update_events = flags & IORING_POLL_UPDATE_EVENTS;937 upd->update_user_data = flags & IORING_POLL_UPDATE_USER_DATA;938 939 upd->new_user_data = READ_ONCE(sqe->off);940 if (!upd->update_user_data && upd->new_user_data)941 return -EINVAL;942 if (upd->update_events)943 upd->events = io_poll_parse_events(sqe, flags);944 else if (sqe->poll32_events)945 return -EINVAL;946 947 return 0;948}949 950int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)951{952 struct io_poll *poll = io_kiocb_to_cmd(req, struct io_poll);953 u32 flags;954 955 if (sqe->buf_index || sqe->off || sqe->addr)956 return -EINVAL;957 flags = READ_ONCE(sqe->len);958 if (flags & ~IORING_POLL_ADD_MULTI)959 return -EINVAL;960 if ((flags & IORING_POLL_ADD_MULTI) && (req->flags & REQ_F_CQE_SKIP))961 return -EINVAL;962 963 poll->events = io_poll_parse_events(sqe, flags);964 return 0;965}966 967int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)968{969 struct io_poll *poll = io_kiocb_to_cmd(req, struct io_poll);970 struct io_poll_table ipt;971 int ret;972 973 ipt.pt._qproc = io_poll_queue_proc;974 975 /*976 * If sqpoll or single issuer, there is no contention for ->uring_lock977 * and we'll end up holding it in tw handlers anyway.978 */979 if (req->ctx->flags & (IORING_SETUP_SQPOLL|IORING_SETUP_SINGLE_ISSUER))980 req->flags |= REQ_F_HASH_LOCKED;981 982 ret = __io_arm_poll_handler(req, poll, &ipt, poll->events, issue_flags);983 if (ret > 0) {984 io_req_set_res(req, ipt.result_mask, 0);985 return IOU_OK;986 }987 return ret ?: IOU_ISSUE_SKIP_COMPLETE;988}989 990int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags)991{992 struct io_poll_update *poll_update = io_kiocb_to_cmd(req, struct io_poll_update);993 struct io_ring_ctx *ctx = req->ctx;994 struct io_cancel_data cd = { .ctx = ctx, .data = poll_update->old_user_data, };995 struct io_hash_bucket *bucket;996 struct io_kiocb *preq;997 int ret2, ret = 0;998 999 io_ring_submit_lock(ctx, issue_flags);1000 preq = io_poll_find(ctx, true, &cd, &ctx->cancel_table, &bucket);1001 ret2 = io_poll_disarm(preq);1002 if (bucket)1003 spin_unlock(&bucket->lock);1004 if (!ret2)1005 goto found;1006 if (ret2 != -ENOENT) {1007 ret = ret2;1008 goto out;1009 }1010 1011 preq = io_poll_find(ctx, true, &cd, &ctx->cancel_table_locked, &bucket);1012 ret2 = io_poll_disarm(preq);1013 if (bucket)1014 spin_unlock(&bucket->lock);1015 if (ret2) {1016 ret = ret2;1017 goto out;1018 }1019 1020found:1021 if (WARN_ON_ONCE(preq->opcode != IORING_OP_POLL_ADD)) {1022 ret = -EFAULT;1023 goto out;1024 }1025 1026 if (poll_update->update_events || poll_update->update_user_data) {1027 /* only mask one event flags, keep behavior flags */1028 if (poll_update->update_events) {1029 struct io_poll *poll = io_kiocb_to_cmd(preq, struct io_poll);1030 1031 poll->events &= ~0xffff;1032 poll->events |= poll_update->events & 0xffff;1033 poll->events |= IO_POLL_UNMASK;1034 }1035 if (poll_update->update_user_data)1036 preq->cqe.user_data = poll_update->new_user_data;1037 1038 ret2 = io_poll_add(preq, issue_flags & ~IO_URING_F_UNLOCKED);1039 /* successfully updated, don't complete poll request */1040 if (!ret2 || ret2 == -EIOCBQUEUED)1041 goto out;1042 }1043 1044 req_set_fail(preq);1045 io_req_set_res(preq, -ECANCELED, 0);1046 preq->io_task_work.func = io_req_task_complete;1047 io_req_task_work_add(preq);1048out:1049 io_ring_submit_unlock(ctx, issue_flags);1050 if (ret < 0) {1051 req_set_fail(req);1052 return ret;1053 }1054 /* complete update request, we're done with it */1055 io_req_set_res(req, ret, 0);1056 return IOU_OK;1057}1058