| // 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 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, bool *locked) |
| { |
| 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, locked); |
| 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, |
| wait_queue_func_t wake_func) |
| { |
| 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, wake_func); |
| } |
| |
| 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, bool *locked) |
| { |
| struct io_ring_ctx *ctx = req->ctx; |
| 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); |
| |
| /* tw handler should be the owner, and so have some references */ |
| if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK))) |
| return IOU_POLL_DONE; |
| if (v & IO_POLL_CANCEL_FLAG) |
| return -ECANCELED; |
| /* |
| * cqe.res contains only events of the first wake up |
| * and all others are 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; |
| if (io_is_uring_fops(req->file)) |
| 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_post_aux_cqe(ctx, req->cqe.user_data, |
| mask, IORING_CQE_F_MORE, false)) { |
| io_req_set_res(req, mask, 0); |
| return IOU_POLL_REMOVE_POLL_USE_RES; |
| } |
| } else { |
| int ret = io_poll_issue(req, locked); |
| 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; |
| } |
| |
| static void io_poll_task_func(struct io_kiocb *req, bool *locked) |
| { |
| int ret; |
| |
| ret = io_poll_check_events(req, locked); |
| if (ret == IOU_POLL_NO_ACTION) |
| return; |
| |
| if (ret == IOU_POLL_DONE) { |
| struct io_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_poll_remove_entries(req); |
| io_poll_tw_hash_eject(req, locked); |
| io_req_task_submit(req, locked); |
| return; |
| } else if (ret != IOU_POLL_REMOVE_POLL_USE_RES) { |
| req->cqe.res = ret; |
| req_set_fail(req); |
| } |
| |
| io_poll_remove_entries(req); |
| io_poll_tw_hash_eject(req, locked); |
| |
| io_req_set_res(req, req->cqe.res, 0); |
| io_req_task_complete(req, locked); |
| } |
| |
| static void io_apoll_task_func(struct io_kiocb *req, bool *locked) |
| { |
| int ret; |
| |
| ret = io_poll_check_events(req, locked); |
| if (ret == IOU_POLL_NO_ACTION) |
| return; |
| |
| io_poll_remove_entries(req); |
| io_poll_tw_hash_eject(req, locked); |
| |
| if (ret == IOU_POLL_REMOVE_POLL_USE_RES) |
| io_req_complete_post(req); |
| else if (ret == IOU_POLL_DONE || ret == IOU_POLL_REISSUE) |
| io_req_task_submit(req, locked); |
| else |
| io_req_complete_failed(req, ret); |
| } |
| |
| static void __io_poll_execute(struct io_kiocb *req, int mask) |
| { |
| io_req_set_res(req, mask, 0); |
| /* |
| * This is useful for poll that is armed on behalf of another |
| * request, and where the wakeup path could be on a different |
| * CPU. We want to avoid pulling in req->apoll->events for that |
| * case. |
| */ |
| if (req->opcode == IORING_OP_POLL_ADD) |
| req->io_task_work.func = io_poll_task_func; |
| else |
| req->io_task_work.func = io_apoll_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, first->wait.func); |
| 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, io_poll_wake); |
| 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_op_def *def = &io_op_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 (!(cd->flags & IORING_ASYNC_CANCEL_ANY) && |
| req->file != cd->file) |
| continue; |
| 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 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_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_cancel_data cd = { .data = poll_update->old_user_data, }; |
| struct io_ring_ctx *ctx = req->ctx; |
| struct io_hash_bucket *bucket; |
| struct io_kiocb *preq; |
| int ret2, ret = 0; |
| bool 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, &locked); |
| 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)); |
| } |