1062 lines
29 KiB
C
1062 lines
29 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/poll.h>
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#include <linux/hashtable.h>
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#include <linux/io_uring.h>
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#include <trace/events/io_uring.h>
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#include <uapi/linux/io_uring.h>
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#include "io_uring.h"
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#include "refs.h"
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#include "opdef.h"
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#include "kbuf.h"
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#include "poll.h"
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#include "cancel.h"
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struct io_poll_update {
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struct file *file;
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u64 old_user_data;
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u64 new_user_data;
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__poll_t events;
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bool update_events;
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bool update_user_data;
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};
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struct io_poll_table {
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struct poll_table_struct pt;
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struct io_kiocb *req;
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int nr_entries;
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int error;
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bool owning;
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/* output value, set only if arm poll returns >0 */
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__poll_t result_mask;
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};
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#define IO_POLL_CANCEL_FLAG BIT(31)
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#define IO_POLL_RETRY_FLAG BIT(30)
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#define IO_POLL_REF_MASK GENMASK(29, 0)
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/*
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* We usually have 1-2 refs taken, 128 is more than enough and we want to
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* maximise the margin between this amount and the moment when it overflows.
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*/
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#define IO_POLL_REF_BIAS 128
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#define IO_WQE_F_DOUBLE 1
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static inline struct io_kiocb *wqe_to_req(struct wait_queue_entry *wqe)
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{
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unsigned long priv = (unsigned long)wqe->private;
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return (struct io_kiocb *)(priv & ~IO_WQE_F_DOUBLE);
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}
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static inline bool wqe_is_double(struct wait_queue_entry *wqe)
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{
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unsigned long priv = (unsigned long)wqe->private;
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return priv & IO_WQE_F_DOUBLE;
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}
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static bool io_poll_get_ownership_slowpath(struct io_kiocb *req)
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{
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int v;
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/*
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* poll_refs are already elevated and we don't have much hope for
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* grabbing the ownership. Instead of incrementing set a retry flag
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* to notify the loop that there might have been some change.
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*/
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v = atomic_fetch_or(IO_POLL_RETRY_FLAG, &req->poll_refs);
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if (v & IO_POLL_REF_MASK)
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return false;
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return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
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}
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/*
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* If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can
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* bump it and acquire ownership. It's disallowed to modify requests while not
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* owning it, that prevents from races for enqueueing task_work's and b/w
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* arming poll and wakeups.
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*/
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static inline bool io_poll_get_ownership(struct io_kiocb *req)
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{
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if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))
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return io_poll_get_ownership_slowpath(req);
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return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
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}
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static void io_poll_mark_cancelled(struct io_kiocb *req)
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{
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atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);
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}
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static struct io_poll *io_poll_get_double(struct io_kiocb *req)
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{
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/* pure poll stashes this in ->async_data, poll driven retry elsewhere */
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if (req->opcode == IORING_OP_POLL_ADD)
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return req->async_data;
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return req->apoll->double_poll;
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}
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static struct io_poll *io_poll_get_single(struct io_kiocb *req)
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{
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if (req->opcode == IORING_OP_POLL_ADD)
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return io_kiocb_to_cmd(req, struct io_poll);
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return &req->apoll->poll;
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}
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static void io_poll_req_insert(struct io_kiocb *req)
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{
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struct io_hash_table *table = &req->ctx->cancel_table;
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u32 index = hash_long(req->cqe.user_data, table->hash_bits);
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struct io_hash_bucket *hb = &table->hbs[index];
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spin_lock(&hb->lock);
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hlist_add_head(&req->hash_node, &hb->list);
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spin_unlock(&hb->lock);
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}
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static void io_poll_req_delete(struct io_kiocb *req, struct io_ring_ctx *ctx)
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{
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struct io_hash_table *table = &req->ctx->cancel_table;
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u32 index = hash_long(req->cqe.user_data, table->hash_bits);
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spinlock_t *lock = &table->hbs[index].lock;
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spin_lock(lock);
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hash_del(&req->hash_node);
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spin_unlock(lock);
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}
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static void io_poll_req_insert_locked(struct io_kiocb *req)
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{
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struct io_hash_table *table = &req->ctx->cancel_table_locked;
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u32 index = hash_long(req->cqe.user_data, table->hash_bits);
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lockdep_assert_held(&req->ctx->uring_lock);
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hlist_add_head(&req->hash_node, &table->hbs[index].list);
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}
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static void io_poll_tw_hash_eject(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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if (req->flags & REQ_F_HASH_LOCKED) {
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/*
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* ->cancel_table_locked is protected by ->uring_lock in
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* contrast to per bucket spinlocks. Likely, tctx_task_work()
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* already grabbed the mutex for us, but there is a chance it
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* failed.
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*/
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io_tw_lock(ctx, locked);
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hash_del(&req->hash_node);
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req->flags &= ~REQ_F_HASH_LOCKED;
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} else {
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io_poll_req_delete(req, ctx);
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}
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}
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static void io_init_poll_iocb(struct io_poll *poll, __poll_t events,
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wait_queue_func_t wake_func)
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{
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poll->head = NULL;
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#define IO_POLL_UNMASK (EPOLLERR|EPOLLHUP|EPOLLNVAL|EPOLLRDHUP)
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/* mask in events that we always want/need */
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poll->events = events | IO_POLL_UNMASK;
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INIT_LIST_HEAD(&poll->wait.entry);
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init_waitqueue_func_entry(&poll->wait, wake_func);
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}
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static inline void io_poll_remove_entry(struct io_poll *poll)
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{
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struct wait_queue_head *head = smp_load_acquire(&poll->head);
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if (head) {
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spin_lock_irq(&head->lock);
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list_del_init(&poll->wait.entry);
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poll->head = NULL;
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spin_unlock_irq(&head->lock);
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}
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}
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static void io_poll_remove_entries(struct io_kiocb *req)
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{
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/*
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* Nothing to do if neither of those flags are set. Avoid dipping
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* into the poll/apoll/double cachelines if we can.
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*/
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if (!(req->flags & (REQ_F_SINGLE_POLL | REQ_F_DOUBLE_POLL)))
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return;
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/*
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* While we hold the waitqueue lock and the waitqueue is nonempty,
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* wake_up_pollfree() will wait for us. However, taking the waitqueue
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* lock in the first place can race with the waitqueue being freed.
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*
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* We solve this as eventpoll does: by taking advantage of the fact that
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* all users of wake_up_pollfree() will RCU-delay the actual free. If
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* we enter rcu_read_lock() and see that the pointer to the queue is
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* non-NULL, we can then lock it without the memory being freed out from
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* under us.
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*
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* Keep holding rcu_read_lock() as long as we hold the queue lock, in
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* case the caller deletes the entry from the queue, leaving it empty.
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* In that case, only RCU prevents the queue memory from being freed.
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*/
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rcu_read_lock();
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if (req->flags & REQ_F_SINGLE_POLL)
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io_poll_remove_entry(io_poll_get_single(req));
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if (req->flags & REQ_F_DOUBLE_POLL)
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io_poll_remove_entry(io_poll_get_double(req));
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rcu_read_unlock();
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}
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enum {
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IOU_POLL_DONE = 0,
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IOU_POLL_NO_ACTION = 1,
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IOU_POLL_REMOVE_POLL_USE_RES = 2,
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IOU_POLL_REISSUE = 3,
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};
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/*
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* All poll tw should go through this. Checks for poll events, manages
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* references, does rewait, etc.
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*
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* Returns a negative error on failure. IOU_POLL_NO_ACTION when no action
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* require, which is either spurious wakeup or multishot CQE is served.
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* IOU_POLL_DONE when it's done with the request, then the mask is stored in
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* req->cqe.res. IOU_POLL_REMOVE_POLL_USE_RES indicates to remove multishot
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* poll and that the result is stored in req->cqe.
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*/
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static int io_poll_check_events(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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int v;
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/* req->task == current here, checking PF_EXITING is safe */
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if (unlikely(req->task->flags & PF_EXITING))
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return -ECANCELED;
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do {
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v = atomic_read(&req->poll_refs);
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/* tw handler should be the owner, and so have some references */
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if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK)))
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return IOU_POLL_DONE;
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if (v & IO_POLL_CANCEL_FLAG)
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return -ECANCELED;
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/*
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* cqe.res contains only events of the first wake up
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* and all others are be lost. Redo vfs_poll() to get
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* up to date state.
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*/
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if ((v & IO_POLL_REF_MASK) != 1)
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req->cqe.res = 0;
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if (v & IO_POLL_RETRY_FLAG) {
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req->cqe.res = 0;
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/*
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* We won't find new events that came in between
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* vfs_poll and the ref put unless we clear the flag
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* in advance.
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*/
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atomic_andnot(IO_POLL_RETRY_FLAG, &req->poll_refs);
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v &= ~IO_POLL_RETRY_FLAG;
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}
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/* the mask was stashed in __io_poll_execute */
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if (!req->cqe.res) {
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struct poll_table_struct pt = { ._key = req->apoll_events };
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req->cqe.res = vfs_poll(req->file, &pt) & req->apoll_events;
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/*
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* We got woken with a mask, but someone else got to
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* it first. The above vfs_poll() doesn't add us back
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* to the waitqueue, so if we get nothing back, we
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* should be safe and attempt a reissue.
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*/
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if (unlikely(!req->cqe.res)) {
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/* Multishot armed need not reissue */
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if (!(req->apoll_events & EPOLLONESHOT))
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continue;
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return IOU_POLL_REISSUE;
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}
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}
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if (req->apoll_events & EPOLLONESHOT)
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return IOU_POLL_DONE;
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if (io_is_uring_fops(req->file))
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return IOU_POLL_DONE;
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/* multishot, just fill a CQE and proceed */
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if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {
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__poll_t mask = mangle_poll(req->cqe.res &
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req->apoll_events);
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if (!io_post_aux_cqe(ctx, req->cqe.user_data,
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mask, IORING_CQE_F_MORE, false)) {
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io_req_set_res(req, mask, 0);
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return IOU_POLL_REMOVE_POLL_USE_RES;
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}
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} else {
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int ret = io_poll_issue(req, locked);
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if (ret == IOU_STOP_MULTISHOT)
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return IOU_POLL_REMOVE_POLL_USE_RES;
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if (ret < 0)
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return ret;
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}
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/* force the next iteration to vfs_poll() */
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req->cqe.res = 0;
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/*
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* Release all references, retry if someone tried to restart
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* task_work while we were executing it.
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*/
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} while (atomic_sub_return(v & IO_POLL_REF_MASK, &req->poll_refs) &
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IO_POLL_REF_MASK);
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return IOU_POLL_NO_ACTION;
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}
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static void io_poll_task_func(struct io_kiocb *req, bool *locked)
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{
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int ret;
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ret = io_poll_check_events(req, locked);
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if (ret == IOU_POLL_NO_ACTION)
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return;
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if (ret == IOU_POLL_DONE) {
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struct io_poll *poll = io_kiocb_to_cmd(req, struct io_poll);
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req->cqe.res = mangle_poll(req->cqe.res & poll->events);
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} else if (ret == IOU_POLL_REISSUE) {
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io_poll_remove_entries(req);
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io_poll_tw_hash_eject(req, locked);
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io_req_task_submit(req, locked);
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return;
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} else if (ret != IOU_POLL_REMOVE_POLL_USE_RES) {
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req->cqe.res = ret;
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req_set_fail(req);
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}
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io_poll_remove_entries(req);
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io_poll_tw_hash_eject(req, locked);
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io_req_set_res(req, req->cqe.res, 0);
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io_req_task_complete(req, locked);
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}
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static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
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{
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int ret;
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ret = io_poll_check_events(req, locked);
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if (ret == IOU_POLL_NO_ACTION)
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return;
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io_tw_lock(req->ctx, locked);
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io_poll_remove_entries(req);
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io_poll_tw_hash_eject(req, locked);
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if (ret == IOU_POLL_REMOVE_POLL_USE_RES)
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io_req_task_complete(req, locked);
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else if (ret == IOU_POLL_DONE || ret == IOU_POLL_REISSUE)
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io_req_task_submit(req, locked);
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else
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io_req_complete_failed(req, ret);
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}
|
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static void __io_poll_execute(struct io_kiocb *req, int mask)
|
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{
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io_req_set_res(req, mask, 0);
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/*
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* This is useful for poll that is armed on behalf of another
|
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* request, and where the wakeup path could be on a different
|
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* CPU. We want to avoid pulling in req->apoll->events for that
|
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* case.
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*/
|
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if (req->opcode == IORING_OP_POLL_ADD)
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req->io_task_work.func = io_poll_task_func;
|
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else
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req->io_task_work.func = io_apoll_task_func;
|
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trace_io_uring_task_add(req, mask);
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io_req_task_work_add(req);
|
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}
|
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static inline void io_poll_execute(struct io_kiocb *req, int res)
|
||
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{
|
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if (io_poll_get_ownership(req))
|
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__io_poll_execute(req, res);
|
||
|
}
|
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|
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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);
|
||
|
}
|
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||
|
#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));
|
||
|
}
|