diff options
Diffstat (limited to 'io_uring/poll.c')
| -rw-r--r-- | io_uring/poll.c | 1041 |
1 files changed, 1041 insertions, 0 deletions
diff --git a/io_uring/poll.c b/io_uring/poll.c new file mode 100644 index 0000000000..4c360ba879 --- /dev/null +++ b/io_uring/poll.c @@ -0,0 +1,1041 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/poll.h> +#include <linux/hashtable.h> +#include <linux/io_uring.h> + +#include <trace/events/io_uring.h> + +#include <uapi/linux/io_uring.h> + +#include "io_uring.h" +#include "refs.h" +#include "opdef.h" +#include "kbuf.h" +#include "poll.h" +#include "cancel.h" + +struct io_poll_update { + struct file *file; + u64 old_user_data; + u64 new_user_data; + __poll_t events; + bool update_events; + bool update_user_data; +}; + +struct io_poll_table { + struct poll_table_struct pt; + struct io_kiocb *req; + int nr_entries; + int error; + bool owning; + /* output value, set only if arm poll returns >0 */ + __poll_t result_mask; +}; + +#define IO_POLL_CANCEL_FLAG BIT(31) +#define IO_POLL_RETRY_FLAG BIT(30) +#define IO_POLL_REF_MASK GENMASK(29, 0) + +/* + * We usually have 1-2 refs taken, 128 is more than enough and we want to + * maximise the margin between this amount and the moment when it overflows. + */ +#define IO_POLL_REF_BIAS 128 + +#define IO_WQE_F_DOUBLE 1 + +static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, + void *key); + +static inline struct io_kiocb *wqe_to_req(struct wait_queue_entry *wqe) +{ + unsigned long priv = (unsigned long)wqe->private; + + return (struct io_kiocb *)(priv & ~IO_WQE_F_DOUBLE); +} + +static inline bool wqe_is_double(struct wait_queue_entry *wqe) +{ + unsigned long priv = (unsigned long)wqe->private; + + return priv & IO_WQE_F_DOUBLE; +} + +static bool io_poll_get_ownership_slowpath(struct io_kiocb *req) +{ + int v; + + /* + * poll_refs are already elevated and we don't have much hope for + * grabbing the ownership. Instead of incrementing set a retry flag + * to notify the loop that there might have been some change. + */ + v = atomic_fetch_or(IO_POLL_RETRY_FLAG, &req->poll_refs); + if (v & IO_POLL_REF_MASK) + return false; + return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK); +} + +/* + * If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can + * bump it and acquire ownership. It's disallowed to modify requests while not + * owning it, that prevents from races for enqueueing task_work's and b/w + * arming poll and wakeups. + */ +static inline bool io_poll_get_ownership(struct io_kiocb *req) +{ + if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) + return io_poll_get_ownership_slowpath(req); + return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK); +} + +static void io_poll_mark_cancelled(struct io_kiocb *req) +{ + atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs); +} + +static struct io_poll *io_poll_get_double(struct io_kiocb *req) +{ + /* pure poll stashes this in ->async_data, poll driven retry elsewhere */ + if (req->opcode == IORING_OP_POLL_ADD) + return req->async_data; + return req->apoll->double_poll; +} + +static struct io_poll *io_poll_get_single(struct io_kiocb *req) +{ + if (req->opcode == IORING_OP_POLL_ADD) + return io_kiocb_to_cmd(req, struct io_poll); + return &req->apoll->poll; +} + +static void io_poll_req_insert(struct io_kiocb *req) +{ + struct io_hash_table *table = &req->ctx->cancel_table; + u32 index = hash_long(req->cqe.user_data, table->hash_bits); + struct io_hash_bucket *hb = &table->hbs[index]; + + spin_lock(&hb->lock); + hlist_add_head(&req->hash_node, &hb->list); + spin_unlock(&hb->lock); +} + +static void io_poll_req_delete(struct io_kiocb *req, struct io_ring_ctx *ctx) +{ + struct io_hash_table *table = &req->ctx->cancel_table; + u32 index = hash_long(req->cqe.user_data, table->hash_bits); + spinlock_t *lock = &table->hbs[index].lock; + + spin_lock(lock); + hash_del(&req->hash_node); + spin_unlock(lock); +} + +static void io_poll_req_insert_locked(struct io_kiocb *req) +{ + struct io_hash_table *table = &req->ctx->cancel_table_locked; + u32 index = hash_long(req->cqe.user_data, table->hash_bits); + + lockdep_assert_held(&req->ctx->uring_lock); + + hlist_add_head(&req->hash_node, &table->hbs[index].list); +} + +static void io_poll_tw_hash_eject(struct io_kiocb *req, struct io_tw_state *ts) +{ + struct io_ring_ctx *ctx = req->ctx; + + if (req->flags & REQ_F_HASH_LOCKED) { + /* + * ->cancel_table_locked is protected by ->uring_lock in + * contrast to per bucket spinlocks. Likely, tctx_task_work() + * already grabbed the mutex for us, but there is a chance it + * failed. + */ + io_tw_lock(ctx, ts); + hash_del(&req->hash_node); + req->flags &= ~REQ_F_HASH_LOCKED; + } else { + io_poll_req_delete(req, ctx); + } +} + +static void io_init_poll_iocb(struct io_poll *poll, __poll_t events) +{ + poll->head = NULL; +#define IO_POLL_UNMASK (EPOLLERR|EPOLLHUP|EPOLLNVAL|EPOLLRDHUP) + /* mask in events that we always want/need */ + poll->events = events | IO_POLL_UNMASK; + INIT_LIST_HEAD(&poll->wait.entry); + init_waitqueue_func_entry(&poll->wait, io_poll_wake); +} + +static inline void io_poll_remove_entry(struct io_poll *poll) +{ + struct wait_queue_head *head = smp_load_acquire(&poll->head); + + if (head) { + spin_lock_irq(&head->lock); + list_del_init(&poll->wait.entry); + poll->head = NULL; + spin_unlock_irq(&head->lock); + } +} + +static void io_poll_remove_entries(struct io_kiocb *req) +{ + /* + * Nothing to do if neither of those flags are set. Avoid dipping + * into the poll/apoll/double cachelines if we can. + */ + if (!(req->flags & (REQ_F_SINGLE_POLL | REQ_F_DOUBLE_POLL))) + return; + + /* + * While we hold the waitqueue lock and the waitqueue is nonempty, + * wake_up_pollfree() will wait for us. However, taking the waitqueue + * lock in the first place can race with the waitqueue being freed. + * + * We solve this as eventpoll does: by taking advantage of the fact that + * all users of wake_up_pollfree() will RCU-delay the actual free. If + * we enter rcu_read_lock() and see that the pointer to the queue is + * non-NULL, we can then lock it without the memory being freed out from + * under us. + * + * Keep holding rcu_read_lock() as long as we hold the queue lock, in + * case the caller deletes the entry from the queue, leaving it empty. + * In that case, only RCU prevents the queue memory from being freed. + */ + rcu_read_lock(); + if (req->flags & REQ_F_SINGLE_POLL) + io_poll_remove_entry(io_poll_get_single(req)); + if (req->flags & REQ_F_DOUBLE_POLL) + io_poll_remove_entry(io_poll_get_double(req)); + rcu_read_unlock(); +} + +enum { + IOU_POLL_DONE = 0, + IOU_POLL_NO_ACTION = 1, + IOU_POLL_REMOVE_POLL_USE_RES = 2, + IOU_POLL_REISSUE = 3, +}; + +/* + * All poll tw should go through this. Checks for poll events, manages + * references, does rewait, etc. + * + * Returns a negative error on failure. IOU_POLL_NO_ACTION when no action + * require, which is either spurious wakeup or multishot CQE is served. + * IOU_POLL_DONE when it's done with the request, then the mask is stored in + * req->cqe.res. IOU_POLL_REMOVE_POLL_USE_RES indicates to remove multishot + * poll and that the result is stored in req->cqe. + */ +static int io_poll_check_events(struct io_kiocb *req, struct io_tw_state *ts) +{ + int v; + + /* req->task == current here, checking PF_EXITING is safe */ + if (unlikely(req->task->flags & PF_EXITING)) + return -ECANCELED; + + do { + v = atomic_read(&req->poll_refs); + + if (unlikely(v != 1)) { + /* tw should be the owner and so have some refs */ + if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK))) + return IOU_POLL_NO_ACTION; + if (v & IO_POLL_CANCEL_FLAG) + return -ECANCELED; + /* + * cqe.res contains only events of the first wake up + * and all others are to be lost. Redo vfs_poll() to get + * up to date state. + */ + if ((v & IO_POLL_REF_MASK) != 1) + req->cqe.res = 0; + + if (v & IO_POLL_RETRY_FLAG) { + req->cqe.res = 0; + /* + * We won't find new events that came in between + * vfs_poll and the ref put unless we clear the + * flag in advance. + */ + atomic_andnot(IO_POLL_RETRY_FLAG, &req->poll_refs); + v &= ~IO_POLL_RETRY_FLAG; + } + } + + /* the mask was stashed in __io_poll_execute */ + if (!req->cqe.res) { + struct poll_table_struct pt = { ._key = req->apoll_events }; + req->cqe.res = vfs_poll(req->file, &pt) & req->apoll_events; + /* + * We got woken with a mask, but someone else got to + * it first. The above vfs_poll() doesn't add us back + * to the waitqueue, so if we get nothing back, we + * should be safe and attempt a reissue. + */ + if (unlikely(!req->cqe.res)) { + /* Multishot armed need not reissue */ + if (!(req->apoll_events & EPOLLONESHOT)) + continue; + return IOU_POLL_REISSUE; + } + } + if (req->apoll_events & EPOLLONESHOT) + return IOU_POLL_DONE; + + /* multishot, just fill a CQE and proceed */ + if (!(req->flags & REQ_F_APOLL_MULTISHOT)) { + __poll_t mask = mangle_poll(req->cqe.res & + req->apoll_events); + + if (!io_fill_cqe_req_aux(req, ts->locked, mask, + IORING_CQE_F_MORE)) { + io_req_set_res(req, mask, 0); + return IOU_POLL_REMOVE_POLL_USE_RES; + } + } else { + int ret = io_poll_issue(req, ts); + if (ret == IOU_STOP_MULTISHOT) + return IOU_POLL_REMOVE_POLL_USE_RES; + if (ret < 0) + return ret; + } + + /* force the next iteration to vfs_poll() */ + req->cqe.res = 0; + + /* + * Release all references, retry if someone tried to restart + * task_work while we were executing it. + */ + } while (atomic_sub_return(v & IO_POLL_REF_MASK, &req->poll_refs) & + IO_POLL_REF_MASK); + + return IOU_POLL_NO_ACTION; +} + +void io_poll_task_func(struct io_kiocb *req, struct io_tw_state *ts) +{ + int ret; + + ret = io_poll_check_events(req, ts); + if (ret == IOU_POLL_NO_ACTION) + return; + io_poll_remove_entries(req); + io_poll_tw_hash_eject(req, ts); + + if (req->opcode == IORING_OP_POLL_ADD) { + if (ret == IOU_POLL_DONE) { + struct io_poll *poll; + + poll = io_kiocb_to_cmd(req, struct io_poll); + req->cqe.res = mangle_poll(req->cqe.res & poll->events); + } else if (ret == IOU_POLL_REISSUE) { + io_req_task_submit(req, ts); + return; + } else if (ret != IOU_POLL_REMOVE_POLL_USE_RES) { + req->cqe.res = ret; + req_set_fail(req); + } + + io_req_set_res(req, req->cqe.res, 0); + io_req_task_complete(req, ts); + } else { + io_tw_lock(req->ctx, ts); + + if (ret == IOU_POLL_REMOVE_POLL_USE_RES) + io_req_task_complete(req, ts); + else if (ret == IOU_POLL_DONE || ret == IOU_POLL_REISSUE) + io_req_task_submit(req, ts); + else + io_req_defer_failed(req, ret); + } +} + +static void __io_poll_execute(struct io_kiocb *req, int mask) +{ + io_req_set_res(req, mask, 0); + req->io_task_work.func = io_poll_task_func; + + trace_io_uring_task_add(req, mask); + io_req_task_work_add(req); +} + +static inline void io_poll_execute(struct io_kiocb *req, int res) +{ + if (io_poll_get_ownership(req)) + __io_poll_execute(req, res); +} + +static void io_poll_cancel_req(struct io_kiocb *req) +{ + io_poll_mark_cancelled(req); + /* kick tw, which should complete the request */ + io_poll_execute(req, 0); +} + +#define IO_ASYNC_POLL_COMMON (EPOLLONESHOT | EPOLLPRI) + +static __cold int io_pollfree_wake(struct io_kiocb *req, struct io_poll *poll) +{ + io_poll_mark_cancelled(req); + /* we have to kick tw in case it's not already */ + io_poll_execute(req, 0); + + /* + * If the waitqueue is being freed early but someone is already + * holds ownership over it, we have to tear down the request as + * best we can. That means immediately removing the request from + * its waitqueue and preventing all further accesses to the + * waitqueue via the request. + */ + list_del_init(&poll->wait.entry); + + /* + * Careful: this *must* be the last step, since as soon + * as req->head is NULL'ed out, the request can be + * completed and freed, since aio_poll_complete_work() + * will no longer need to take the waitqueue lock. + */ + smp_store_release(&poll->head, NULL); + return 1; +} + +static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, + void *key) +{ + struct io_kiocb *req = wqe_to_req(wait); + struct io_poll *poll = container_of(wait, struct io_poll, wait); + __poll_t mask = key_to_poll(key); + + if (unlikely(mask & POLLFREE)) + return io_pollfree_wake(req, poll); + + /* for instances that support it check for an event match first */ + if (mask && !(mask & (poll->events & ~IO_ASYNC_POLL_COMMON))) + return 0; + + if (io_poll_get_ownership(req)) { + /* + * If we trigger a multishot poll off our own wakeup path, + * disable multishot as there is a circular dependency between + * CQ posting and triggering the event. + */ + if (mask & EPOLL_URING_WAKE) + poll->events |= EPOLLONESHOT; + + /* optional, saves extra locking for removal in tw handler */ + if (mask && poll->events & EPOLLONESHOT) { + list_del_init(&poll->wait.entry); + poll->head = NULL; + if (wqe_is_double(wait)) + req->flags &= ~REQ_F_DOUBLE_POLL; + else + req->flags &= ~REQ_F_SINGLE_POLL; + } + __io_poll_execute(req, mask); + } + return 1; +} + +/* fails only when polling is already completing by the first entry */ +static bool io_poll_double_prepare(struct io_kiocb *req) +{ + struct wait_queue_head *head; + struct io_poll *poll = io_poll_get_single(req); + + /* head is RCU protected, see io_poll_remove_entries() comments */ + rcu_read_lock(); + head = smp_load_acquire(&poll->head); + /* + * poll arm might not hold ownership and so race for req->flags with + * io_poll_wake(). There is only one poll entry queued, serialise with + * it by taking its head lock. As we're still arming the tw hanlder + * is not going to be run, so there are no races with it. + */ + if (head) { + spin_lock_irq(&head->lock); + req->flags |= REQ_F_DOUBLE_POLL; + if (req->opcode == IORING_OP_POLL_ADD) + req->flags |= REQ_F_ASYNC_DATA; + spin_unlock_irq(&head->lock); + } + rcu_read_unlock(); + return !!head; +} + +static void __io_queue_proc(struct io_poll *poll, struct io_poll_table *pt, + struct wait_queue_head *head, + struct io_poll **poll_ptr) +{ + struct io_kiocb *req = pt->req; + unsigned long wqe_private = (unsigned long) req; + + /* + * The file being polled uses multiple waitqueues for poll handling + * (e.g. one for read, one for write). Setup a separate io_poll + * if this happens. + */ + if (unlikely(pt->nr_entries)) { + struct io_poll *first = poll; + + /* double add on the same waitqueue head, ignore */ + if (first->head == head) + return; + /* already have a 2nd entry, fail a third attempt */ + if (*poll_ptr) { + if ((*poll_ptr)->head == head) + return; + pt->error = -EINVAL; + return; + } + + poll = kmalloc(sizeof(*poll), GFP_ATOMIC); + if (!poll) { + pt->error = -ENOMEM; + return; + } + + /* mark as double wq entry */ + wqe_private |= IO_WQE_F_DOUBLE; + io_init_poll_iocb(poll, first->events); + if (!io_poll_double_prepare(req)) { + /* the request is completing, just back off */ + kfree(poll); + return; + } + *poll_ptr = poll; + } else { + /* fine to modify, there is no poll queued to race with us */ + req->flags |= REQ_F_SINGLE_POLL; + } + + pt->nr_entries++; + poll->head = head; + poll->wait.private = (void *) wqe_private; + + if (poll->events & EPOLLEXCLUSIVE) + add_wait_queue_exclusive(head, &poll->wait); + else + add_wait_queue(head, &poll->wait); +} + +static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head, + struct poll_table_struct *p) +{ + struct io_poll_table *pt = container_of(p, struct io_poll_table, pt); + struct io_poll *poll = io_kiocb_to_cmd(pt->req, struct io_poll); + + __io_queue_proc(poll, pt, head, + (struct io_poll **) &pt->req->async_data); +} + +static bool io_poll_can_finish_inline(struct io_kiocb *req, + struct io_poll_table *pt) +{ + return pt->owning || io_poll_get_ownership(req); +} + +static void io_poll_add_hash(struct io_kiocb *req) +{ + if (req->flags & REQ_F_HASH_LOCKED) + io_poll_req_insert_locked(req); + else + io_poll_req_insert(req); +} + +/* + * Returns 0 when it's handed over for polling. The caller owns the requests if + * it returns non-zero, but otherwise should not touch it. Negative values + * contain an error code. When the result is >0, the polling has completed + * inline and ipt.result_mask is set to the mask. + */ +static int __io_arm_poll_handler(struct io_kiocb *req, + struct io_poll *poll, + struct io_poll_table *ipt, __poll_t mask, + unsigned issue_flags) +{ + struct io_ring_ctx *ctx = req->ctx; + + INIT_HLIST_NODE(&req->hash_node); + req->work.cancel_seq = atomic_read(&ctx->cancel_seq); + io_init_poll_iocb(poll, mask); + poll->file = req->file; + req->apoll_events = poll->events; + + ipt->pt._key = mask; + ipt->req = req; + ipt->error = 0; + ipt->nr_entries = 0; + /* + * Polling is either completed here or via task_work, so if we're in the + * task context we're naturally serialised with tw by merit of running + * the same task. When it's io-wq, take the ownership to prevent tw + * from running. However, when we're in the task context, skip taking + * it as an optimisation. + * + * Note: even though the request won't be completed/freed, without + * ownership we still can race with io_poll_wake(). + * io_poll_can_finish_inline() tries to deal with that. + */ + ipt->owning = issue_flags & IO_URING_F_UNLOCKED; + atomic_set(&req->poll_refs, (int)ipt->owning); + + /* io-wq doesn't hold uring_lock */ + if (issue_flags & IO_URING_F_UNLOCKED) + req->flags &= ~REQ_F_HASH_LOCKED; + + mask = vfs_poll(req->file, &ipt->pt) & poll->events; + + if (unlikely(ipt->error || !ipt->nr_entries)) { + io_poll_remove_entries(req); + + if (!io_poll_can_finish_inline(req, ipt)) { + io_poll_mark_cancelled(req); + return 0; + } else if (mask && (poll->events & EPOLLET)) { + ipt->result_mask = mask; + return 1; + } + return ipt->error ?: -EINVAL; + } + + if (mask && + ((poll->events & (EPOLLET|EPOLLONESHOT)) == (EPOLLET|EPOLLONESHOT))) { + if (!io_poll_can_finish_inline(req, ipt)) { + io_poll_add_hash(req); + return 0; + } + io_poll_remove_entries(req); + ipt->result_mask = mask; + /* no one else has access to the req, forget about the ref */ + return 1; + } + + io_poll_add_hash(req); + + if (mask && (poll->events & EPOLLET) && + io_poll_can_finish_inline(req, ipt)) { + __io_poll_execute(req, mask); + return 0; + } + + if (ipt->owning) { + /* + * Try to release ownership. If we see a change of state, e.g. + * poll was waken up, queue up a tw, it'll deal with it. + */ + if (atomic_cmpxchg(&req->poll_refs, 1, 0) != 1) + __io_poll_execute(req, 0); + } + return 0; +} + +static void io_async_queue_proc(struct file *file, struct wait_queue_head *head, + struct poll_table_struct *p) +{ + struct io_poll_table *pt = container_of(p, struct io_poll_table, pt); + struct async_poll *apoll = pt->req->apoll; + + __io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll); +} + +/* + * We can't reliably detect loops in repeated poll triggers and issue + * subsequently failing. But rather than fail these immediately, allow a + * certain amount of retries before we give up. Given that this condition + * should _rarely_ trigger even once, we should be fine with a larger value. + */ +#define APOLL_MAX_RETRY 128 + +static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req, + unsigned issue_flags) +{ + struct io_ring_ctx *ctx = req->ctx; + struct io_cache_entry *entry; + struct async_poll *apoll; + + if (req->flags & REQ_F_POLLED) { + apoll = req->apoll; + kfree(apoll->double_poll); + } else if (!(issue_flags & IO_URING_F_UNLOCKED)) { + entry = io_alloc_cache_get(&ctx->apoll_cache); + if (entry == NULL) + goto alloc_apoll; + apoll = container_of(entry, struct async_poll, cache); + apoll->poll.retries = APOLL_MAX_RETRY; + } else { +alloc_apoll: + apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC); + if (unlikely(!apoll)) + return NULL; + apoll->poll.retries = APOLL_MAX_RETRY; + } + apoll->double_poll = NULL; + req->apoll = apoll; + if (unlikely(!--apoll->poll.retries)) + return NULL; + return apoll; +} + +int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags) +{ + const struct io_issue_def *def = &io_issue_defs[req->opcode]; + struct async_poll *apoll; + struct io_poll_table ipt; + __poll_t mask = POLLPRI | POLLERR | EPOLLET; + int ret; + + /* + * apoll requests already grab the mutex to complete in the tw handler, + * so removal from the mutex-backed hash is free, use it by default. + */ + req->flags |= REQ_F_HASH_LOCKED; + + if (!def->pollin && !def->pollout) + return IO_APOLL_ABORTED; + if (!file_can_poll(req->file)) + return IO_APOLL_ABORTED; + if (!(req->flags & REQ_F_APOLL_MULTISHOT)) + mask |= EPOLLONESHOT; + + if (def->pollin) { + mask |= EPOLLIN | EPOLLRDNORM; + + /* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */ + if (req->flags & REQ_F_CLEAR_POLLIN) + mask &= ~EPOLLIN; + } else { + mask |= EPOLLOUT | EPOLLWRNORM; + } + if (def->poll_exclusive) + mask |= EPOLLEXCLUSIVE; + + apoll = io_req_alloc_apoll(req, issue_flags); + if (!apoll) + return IO_APOLL_ABORTED; + req->flags &= ~(REQ_F_SINGLE_POLL | REQ_F_DOUBLE_POLL); + req->flags |= REQ_F_POLLED; + ipt.pt._qproc = io_async_queue_proc; + + io_kbuf_recycle(req, issue_flags); + + ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask, issue_flags); + if (ret) + return ret > 0 ? IO_APOLL_READY : IO_APOLL_ABORTED; + trace_io_uring_poll_arm(req, mask, apoll->poll.events); + return IO_APOLL_OK; +} + +static __cold bool io_poll_remove_all_table(struct task_struct *tsk, + struct io_hash_table *table, + bool cancel_all) +{ + unsigned nr_buckets = 1U << table->hash_bits; + struct hlist_node *tmp; + struct io_kiocb *req; + bool found = false; + int i; + + for (i = 0; i < nr_buckets; i++) { + struct io_hash_bucket *hb = &table->hbs[i]; + + spin_lock(&hb->lock); + hlist_for_each_entry_safe(req, tmp, &hb->list, hash_node) { + if (io_match_task_safe(req, tsk, cancel_all)) { + hlist_del_init(&req->hash_node); + io_poll_cancel_req(req); + found = true; + } + } + spin_unlock(&hb->lock); + } + return found; +} + +/* + * Returns true if we found and killed one or more poll requests + */ +__cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk, + bool cancel_all) + __must_hold(&ctx->uring_lock) +{ + bool ret; + + ret = io_poll_remove_all_table(tsk, &ctx->cancel_table, cancel_all); + ret |= io_poll_remove_all_table(tsk, &ctx->cancel_table_locked, cancel_all); + return ret; +} + +static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only, + struct io_cancel_data *cd, + struct io_hash_table *table, + struct io_hash_bucket **out_bucket) +{ + struct io_kiocb *req; + u32 index = hash_long(cd->data, table->hash_bits); + struct io_hash_bucket *hb = &table->hbs[index]; + + *out_bucket = NULL; + + spin_lock(&hb->lock); + hlist_for_each_entry(req, &hb->list, hash_node) { + if (cd->data != req->cqe.user_data) + continue; + if (poll_only && req->opcode != IORING_OP_POLL_ADD) + continue; + if (cd->flags & IORING_ASYNC_CANCEL_ALL) { + if (cd->seq == req->work.cancel_seq) + continue; + req->work.cancel_seq = cd->seq; + } + *out_bucket = hb; + return req; + } + spin_unlock(&hb->lock); + return NULL; +} + +static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx, + struct io_cancel_data *cd, + struct io_hash_table *table, + struct io_hash_bucket **out_bucket) +{ + unsigned nr_buckets = 1U << table->hash_bits; + struct io_kiocb *req; + int i; + + *out_bucket = NULL; + + for (i = 0; i < nr_buckets; i++) { + struct io_hash_bucket *hb = &table->hbs[i]; + + spin_lock(&hb->lock); + hlist_for_each_entry(req, &hb->list, hash_node) { + if (io_cancel_req_match(req, cd)) { + *out_bucket = hb; + return req; + } + } + spin_unlock(&hb->lock); + } + return NULL; +} + +static int io_poll_disarm(struct io_kiocb *req) +{ + if (!req) + return -ENOENT; + if (!io_poll_get_ownership(req)) + return -EALREADY; + io_poll_remove_entries(req); + hash_del(&req->hash_node); + return 0; +} + +static int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + struct io_hash_table *table) +{ + struct io_hash_bucket *bucket; + struct io_kiocb *req; + + if (cd->flags & (IORING_ASYNC_CANCEL_FD | IORING_ASYNC_CANCEL_OP | + IORING_ASYNC_CANCEL_ANY)) + req = io_poll_file_find(ctx, cd, table, &bucket); + else + req = io_poll_find(ctx, false, cd, table, &bucket); + + if (req) + io_poll_cancel_req(req); + if (bucket) + spin_unlock(&bucket->lock); + return req ? 0 : -ENOENT; +} + +int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + unsigned issue_flags) +{ + int ret; + + ret = __io_poll_cancel(ctx, cd, &ctx->cancel_table); + if (ret != -ENOENT) + return ret; + + io_ring_submit_lock(ctx, issue_flags); + ret = __io_poll_cancel(ctx, cd, &ctx->cancel_table_locked); + io_ring_submit_unlock(ctx, issue_flags); + return ret; +} + +static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe, + unsigned int flags) +{ + u32 events; + + events = READ_ONCE(sqe->poll32_events); +#ifdef __BIG_ENDIAN + events = swahw32(events); +#endif + if (!(flags & IORING_POLL_ADD_MULTI)) + events |= EPOLLONESHOT; + if (!(flags & IORING_POLL_ADD_LEVEL)) + events |= EPOLLET; + return demangle_poll(events) | + (events & (EPOLLEXCLUSIVE|EPOLLONESHOT|EPOLLET)); +} + +int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_poll_update *upd = io_kiocb_to_cmd(req, struct io_poll_update); + u32 flags; + + if (sqe->buf_index || sqe->splice_fd_in) + return -EINVAL; + flags = READ_ONCE(sqe->len); + if (flags & ~(IORING_POLL_UPDATE_EVENTS | IORING_POLL_UPDATE_USER_DATA | + IORING_POLL_ADD_MULTI)) + return -EINVAL; + /* meaningless without update */ + if (flags == IORING_POLL_ADD_MULTI) + return -EINVAL; + + upd->old_user_data = READ_ONCE(sqe->addr); + upd->update_events = flags & IORING_POLL_UPDATE_EVENTS; + upd->update_user_data = flags & IORING_POLL_UPDATE_USER_DATA; + + upd->new_user_data = READ_ONCE(sqe->off); + if (!upd->update_user_data && upd->new_user_data) + return -EINVAL; + if (upd->update_events) + upd->events = io_poll_parse_events(sqe, flags); + else if (sqe->poll32_events) + return -EINVAL; + + return 0; +} + +int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_poll *poll = io_kiocb_to_cmd(req, struct io_poll); + u32 flags; + + if (sqe->buf_index || sqe->off || sqe->addr) + return -EINVAL; + flags = READ_ONCE(sqe->len); + if (flags & ~IORING_POLL_ADD_MULTI) + return -EINVAL; + if ((flags & IORING_POLL_ADD_MULTI) && (req->flags & REQ_F_CQE_SKIP)) + return -EINVAL; + + poll->events = io_poll_parse_events(sqe, flags); + return 0; +} + +int io_poll_add(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_poll *poll = io_kiocb_to_cmd(req, struct io_poll); + struct io_poll_table ipt; + int ret; + + ipt.pt._qproc = io_poll_queue_proc; + + /* + * If sqpoll or single issuer, there is no contention for ->uring_lock + * and we'll end up holding it in tw handlers anyway. + */ + if (req->ctx->flags & (IORING_SETUP_SQPOLL|IORING_SETUP_SINGLE_ISSUER)) + req->flags |= REQ_F_HASH_LOCKED; + + ret = __io_arm_poll_handler(req, poll, &ipt, poll->events, issue_flags); + if (ret > 0) { + io_req_set_res(req, ipt.result_mask, 0); + return IOU_OK; + } + return ret ?: IOU_ISSUE_SKIP_COMPLETE; +} + +int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_poll_update *poll_update = io_kiocb_to_cmd(req, struct io_poll_update); + struct io_ring_ctx *ctx = req->ctx; + struct io_cancel_data cd = { .ctx = ctx, .data = poll_update->old_user_data, }; + struct io_hash_bucket *bucket; + struct io_kiocb *preq; + int ret2, ret = 0; + struct io_tw_state ts = { .locked = true }; + + io_ring_submit_lock(ctx, issue_flags); + preq = io_poll_find(ctx, true, &cd, &ctx->cancel_table, &bucket); + ret2 = io_poll_disarm(preq); + if (bucket) + spin_unlock(&bucket->lock); + if (!ret2) + goto found; + if (ret2 != -ENOENT) { + ret = ret2; + goto out; + } + + preq = io_poll_find(ctx, true, &cd, &ctx->cancel_table_locked, &bucket); + ret2 = io_poll_disarm(preq); + if (bucket) + spin_unlock(&bucket->lock); + if (ret2) { + ret = ret2; + goto out; + } + +found: + if (WARN_ON_ONCE(preq->opcode != IORING_OP_POLL_ADD)) { + ret = -EFAULT; + goto out; + } + + if (poll_update->update_events || poll_update->update_user_data) { + /* only mask one event flags, keep behavior flags */ + if (poll_update->update_events) { + struct io_poll *poll = io_kiocb_to_cmd(preq, struct io_poll); + + poll->events &= ~0xffff; + poll->events |= poll_update->events & 0xffff; + poll->events |= IO_POLL_UNMASK; + } + if (poll_update->update_user_data) + preq->cqe.user_data = poll_update->new_user_data; + + ret2 = io_poll_add(preq, issue_flags & ~IO_URING_F_UNLOCKED); + /* successfully updated, don't complete poll request */ + if (!ret2 || ret2 == -EIOCBQUEUED) + goto out; + } + + req_set_fail(preq); + io_req_set_res(preq, -ECANCELED, 0); + io_req_task_complete(preq, &ts); +out: + io_ring_submit_unlock(ctx, issue_flags); + if (ret < 0) { + req_set_fail(req); + return ret; + } + /* complete update request, we're done with it */ + io_req_set_res(req, ret, 0); + return IOU_OK; +} + +void io_apoll_cache_free(struct io_cache_entry *entry) +{ + kfree(container_of(entry, struct async_poll, cache)); +} |