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synced 2024-09-06 09:51:23 +00:00
![Jens Axboe](/assets/img/avatar_default.png)
While testing io_uring NAPI with DEFER_TASKRUN, I ran into slowdowns and
stalls in packet delivery. Turns out that while
io_napi_busy_loop_should_end() aborts appropriately on regular
task_work, it does not abort if we have local task_work pending.
Move io_has_work() into the private io_uring.h header, and gate whether
we should continue polling on that as well. This makes NAPI polling on
send/receive work as designed with IORING_SETUP_DEFER_TASKRUN as well.
Fixes: 8d0c12a80c
("io-uring: add napi busy poll support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
463 lines
13 KiB
C
463 lines
13 KiB
C
#ifndef IOU_CORE_H
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#define IOU_CORE_H
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#include <linux/errno.h>
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#include <linux/lockdep.h>
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#include <linux/resume_user_mode.h>
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#include <linux/kasan.h>
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#include <linux/poll.h>
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#include <linux/io_uring_types.h>
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#include <uapi/linux/eventpoll.h>
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#include "io-wq.h"
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#include "slist.h"
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#include "filetable.h"
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#ifndef CREATE_TRACE_POINTS
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#include <trace/events/io_uring.h>
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#endif
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enum {
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IOU_OK = 0,
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IOU_ISSUE_SKIP_COMPLETE = -EIOCBQUEUED,
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/*
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* Requeue the task_work to restart operations on this request. The
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* actual value isn't important, should just be not an otherwise
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* valid error code, yet less than -MAX_ERRNO and valid internally.
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*/
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IOU_REQUEUE = -3072,
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/*
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* Intended only when both IO_URING_F_MULTISHOT is passed
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* to indicate to the poll runner that multishot should be
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* removed and the result is set on req->cqe.res.
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*/
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IOU_STOP_MULTISHOT = -ECANCELED,
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};
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struct io_wait_queue {
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struct wait_queue_entry wq;
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struct io_ring_ctx *ctx;
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unsigned cq_tail;
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unsigned nr_timeouts;
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ktime_t timeout;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned int napi_busy_poll_to;
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bool napi_prefer_busy_poll;
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#endif
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};
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static inline bool io_should_wake(struct io_wait_queue *iowq)
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{
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struct io_ring_ctx *ctx = iowq->ctx;
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int dist = READ_ONCE(ctx->rings->cq.tail) - (int) iowq->cq_tail;
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/*
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* Wake up if we have enough events, or if a timeout occurred since we
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* started waiting. For timeouts, we always want to return to userspace,
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* regardless of event count.
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*/
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return dist >= 0 || atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
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}
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bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow);
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void io_req_cqe_overflow(struct io_kiocb *req);
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int io_run_task_work_sig(struct io_ring_ctx *ctx);
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void io_req_defer_failed(struct io_kiocb *req, s32 res);
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void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags);
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bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
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bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags);
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void __io_commit_cqring_flush(struct io_ring_ctx *ctx);
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struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages);
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struct file *io_file_get_normal(struct io_kiocb *req, int fd);
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struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
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unsigned issue_flags);
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void __io_req_task_work_add(struct io_kiocb *req, unsigned flags);
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bool io_alloc_async_data(struct io_kiocb *req);
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void io_req_task_queue(struct io_kiocb *req);
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void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use);
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void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts);
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void io_req_task_queue_fail(struct io_kiocb *req, int ret);
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void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts);
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struct llist_node *io_handle_tw_list(struct llist_node *node, unsigned int *count, unsigned int max_entries);
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struct llist_node *tctx_task_work_run(struct io_uring_task *tctx, unsigned int max_entries, unsigned int *count);
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void tctx_task_work(struct callback_head *cb);
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__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd);
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int io_uring_alloc_task_context(struct task_struct *task,
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struct io_ring_ctx *ctx);
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int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,
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int start, int end);
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int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts);
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int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr);
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int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin);
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void __io_submit_flush_completions(struct io_ring_ctx *ctx);
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int io_req_prep_async(struct io_kiocb *req);
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struct io_wq_work *io_wq_free_work(struct io_wq_work *work);
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void io_wq_submit_work(struct io_wq_work *work);
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void io_free_req(struct io_kiocb *req);
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void io_queue_next(struct io_kiocb *req);
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void io_task_refs_refill(struct io_uring_task *tctx);
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bool __io_alloc_req_refill(struct io_ring_ctx *ctx);
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bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
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bool cancel_all);
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void *io_mem_alloc(size_t size);
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void io_mem_free(void *ptr);
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enum {
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IO_EVENTFD_OP_SIGNAL_BIT,
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IO_EVENTFD_OP_FREE_BIT,
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};
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void io_eventfd_ops(struct rcu_head *rcu);
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void io_activate_pollwq(struct io_ring_ctx *ctx);
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#if defined(CONFIG_PROVE_LOCKING)
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static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
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{
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lockdep_assert(in_task());
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if (ctx->flags & IORING_SETUP_IOPOLL) {
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lockdep_assert_held(&ctx->uring_lock);
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} else if (!ctx->task_complete) {
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lockdep_assert_held(&ctx->completion_lock);
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} else if (ctx->submitter_task) {
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/*
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* ->submitter_task may be NULL and we can still post a CQE,
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* if the ring has been setup with IORING_SETUP_R_DISABLED.
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* Not from an SQE, as those cannot be submitted, but via
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* updating tagged resources.
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*/
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if (ctx->submitter_task->flags & PF_EXITING)
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lockdep_assert(current_work());
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else
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lockdep_assert(current == ctx->submitter_task);
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}
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}
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#else
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static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
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{
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}
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#endif
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static inline void io_req_task_work_add(struct io_kiocb *req)
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{
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__io_req_task_work_add(req, 0);
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}
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#define io_for_each_link(pos, head) \
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for (pos = (head); pos; pos = pos->link)
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static inline bool io_get_cqe_overflow(struct io_ring_ctx *ctx,
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struct io_uring_cqe **ret,
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bool overflow)
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{
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io_lockdep_assert_cq_locked(ctx);
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if (unlikely(ctx->cqe_cached >= ctx->cqe_sentinel)) {
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if (unlikely(!io_cqe_cache_refill(ctx, overflow)))
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return false;
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}
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*ret = ctx->cqe_cached;
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ctx->cached_cq_tail++;
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ctx->cqe_cached++;
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if (ctx->flags & IORING_SETUP_CQE32)
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ctx->cqe_cached++;
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return true;
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}
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static inline bool io_get_cqe(struct io_ring_ctx *ctx, struct io_uring_cqe **ret)
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{
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return io_get_cqe_overflow(ctx, ret, false);
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}
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static __always_inline bool io_fill_cqe_req(struct io_ring_ctx *ctx,
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struct io_kiocb *req)
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{
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struct io_uring_cqe *cqe;
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/*
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* If we can't get a cq entry, userspace overflowed the
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* submission (by quite a lot). Increment the overflow count in
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* the ring.
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*/
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if (unlikely(!io_get_cqe(ctx, &cqe)))
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return false;
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if (trace_io_uring_complete_enabled())
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trace_io_uring_complete(req->ctx, req, req->cqe.user_data,
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req->cqe.res, req->cqe.flags,
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req->big_cqe.extra1, req->big_cqe.extra2);
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memcpy(cqe, &req->cqe, sizeof(*cqe));
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if (ctx->flags & IORING_SETUP_CQE32) {
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memcpy(cqe->big_cqe, &req->big_cqe, sizeof(*cqe));
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memset(&req->big_cqe, 0, sizeof(req->big_cqe));
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}
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return true;
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}
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static inline void req_set_fail(struct io_kiocb *req)
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{
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req->flags |= REQ_F_FAIL;
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if (req->flags & REQ_F_CQE_SKIP) {
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req->flags &= ~REQ_F_CQE_SKIP;
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req->flags |= REQ_F_SKIP_LINK_CQES;
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}
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}
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static inline void io_req_set_res(struct io_kiocb *req, s32 res, u32 cflags)
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{
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req->cqe.res = res;
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req->cqe.flags = cflags;
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}
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static inline bool req_has_async_data(struct io_kiocb *req)
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{
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return req->flags & REQ_F_ASYNC_DATA;
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}
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static inline void io_put_file(struct io_kiocb *req)
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{
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if (!(req->flags & REQ_F_FIXED_FILE) && req->file)
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fput(req->file);
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}
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static inline void io_ring_submit_unlock(struct io_ring_ctx *ctx,
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unsigned issue_flags)
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{
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lockdep_assert_held(&ctx->uring_lock);
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if (unlikely(issue_flags & IO_URING_F_UNLOCKED))
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mutex_unlock(&ctx->uring_lock);
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}
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static inline void io_ring_submit_lock(struct io_ring_ctx *ctx,
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unsigned issue_flags)
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{
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/*
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* "Normal" inline submissions always hold the uring_lock, since we
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* grab it from the system call. Same is true for the SQPOLL offload.
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* The only exception is when we've detached the request and issue it
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* from an async worker thread, grab the lock for that case.
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*/
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if (unlikely(issue_flags & IO_URING_F_UNLOCKED))
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mutex_lock(&ctx->uring_lock);
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lockdep_assert_held(&ctx->uring_lock);
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}
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static inline void io_commit_cqring(struct io_ring_ctx *ctx)
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{
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/* order cqe stores with ring update */
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smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail);
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}
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static inline void io_poll_wq_wake(struct io_ring_ctx *ctx)
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{
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if (wq_has_sleeper(&ctx->poll_wq))
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__wake_up(&ctx->poll_wq, TASK_NORMAL, 0,
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poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
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}
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static inline void io_cqring_wake(struct io_ring_ctx *ctx)
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{
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/*
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* Trigger waitqueue handler on all waiters on our waitqueue. This
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* won't necessarily wake up all the tasks, io_should_wake() will make
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* that decision.
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*
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* Pass in EPOLLIN|EPOLL_URING_WAKE as the poll wakeup key. The latter
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* set in the mask so that if we recurse back into our own poll
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* waitqueue handlers, we know we have a dependency between eventfd or
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* epoll and should terminate multishot poll at that point.
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*/
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if (wq_has_sleeper(&ctx->cq_wait))
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__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
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poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
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}
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static inline bool io_sqring_full(struct io_ring_ctx *ctx)
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{
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struct io_rings *r = ctx->rings;
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return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
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}
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static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
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{
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struct io_rings *rings = ctx->rings;
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unsigned int entries;
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/* make sure SQ entry isn't read before tail */
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entries = smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
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return min(entries, ctx->sq_entries);
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}
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static inline int io_run_task_work(void)
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{
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bool ret = false;
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/*
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* Always check-and-clear the task_work notification signal. With how
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* signaling works for task_work, we can find it set with nothing to
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* run. We need to clear it for that case, like get_signal() does.
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*/
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if (test_thread_flag(TIF_NOTIFY_SIGNAL))
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clear_notify_signal();
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/*
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* PF_IO_WORKER never returns to userspace, so check here if we have
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* notify work that needs processing.
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*/
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if (current->flags & PF_IO_WORKER) {
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if (test_thread_flag(TIF_NOTIFY_RESUME)) {
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__set_current_state(TASK_RUNNING);
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resume_user_mode_work(NULL);
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}
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if (current->io_uring) {
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unsigned int count = 0;
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tctx_task_work_run(current->io_uring, UINT_MAX, &count);
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if (count)
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ret = true;
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}
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}
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if (task_work_pending(current)) {
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__set_current_state(TASK_RUNNING);
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task_work_run();
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ret = true;
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}
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return ret;
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}
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static inline bool io_task_work_pending(struct io_ring_ctx *ctx)
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{
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return task_work_pending(current) || !wq_list_empty(&ctx->work_llist);
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}
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static inline void io_tw_lock(struct io_ring_ctx *ctx, struct io_tw_state *ts)
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{
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if (!ts->locked) {
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mutex_lock(&ctx->uring_lock);
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ts->locked = true;
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}
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}
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/*
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* Don't complete immediately but use deferred completion infrastructure.
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* Protected by ->uring_lock and can only be used either with
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* IO_URING_F_COMPLETE_DEFER or inside a tw handler holding the mutex.
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*/
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static inline void io_req_complete_defer(struct io_kiocb *req)
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__must_hold(&req->ctx->uring_lock)
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{
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struct io_submit_state *state = &req->ctx->submit_state;
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lockdep_assert_held(&req->ctx->uring_lock);
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wq_list_add_tail(&req->comp_list, &state->compl_reqs);
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}
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static inline void io_commit_cqring_flush(struct io_ring_ctx *ctx)
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{
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if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
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ctx->has_evfd || ctx->poll_activated))
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__io_commit_cqring_flush(ctx);
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}
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static inline void io_get_task_refs(int nr)
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{
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struct io_uring_task *tctx = current->io_uring;
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tctx->cached_refs -= nr;
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if (unlikely(tctx->cached_refs < 0))
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io_task_refs_refill(tctx);
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}
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static inline bool io_req_cache_empty(struct io_ring_ctx *ctx)
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{
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return !ctx->submit_state.free_list.next;
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}
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extern struct kmem_cache *req_cachep;
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extern struct kmem_cache *io_buf_cachep;
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static inline struct io_kiocb *io_extract_req(struct io_ring_ctx *ctx)
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{
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struct io_kiocb *req;
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req = container_of(ctx->submit_state.free_list.next, struct io_kiocb, comp_list);
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wq_stack_extract(&ctx->submit_state.free_list);
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return req;
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}
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static inline bool io_alloc_req(struct io_ring_ctx *ctx, struct io_kiocb **req)
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{
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if (unlikely(io_req_cache_empty(ctx))) {
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if (!__io_alloc_req_refill(ctx))
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return false;
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}
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*req = io_extract_req(ctx);
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return true;
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}
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static inline bool io_allowed_defer_tw_run(struct io_ring_ctx *ctx)
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{
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return likely(ctx->submitter_task == current);
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}
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static inline bool io_allowed_run_tw(struct io_ring_ctx *ctx)
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{
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return likely(!(ctx->flags & IORING_SETUP_DEFER_TASKRUN) ||
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ctx->submitter_task == current);
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}
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static inline void io_req_queue_tw_complete(struct io_kiocb *req, s32 res)
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{
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io_req_set_res(req, res, 0);
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req->io_task_work.func = io_req_task_complete;
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io_req_task_work_add(req);
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}
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/*
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* IORING_SETUP_SQE128 contexts allocate twice the normal SQE size for each
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* slot.
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*/
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static inline size_t uring_sqe_size(struct io_ring_ctx *ctx)
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{
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if (ctx->flags & IORING_SETUP_SQE128)
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return 2 * sizeof(struct io_uring_sqe);
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return sizeof(struct io_uring_sqe);
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}
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static inline bool io_file_can_poll(struct io_kiocb *req)
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{
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if (req->flags & REQ_F_CAN_POLL)
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return true;
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if (file_can_poll(req->file)) {
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req->flags |= REQ_F_CAN_POLL;
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return true;
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}
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return false;
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}
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enum {
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IO_CHECK_CQ_OVERFLOW_BIT,
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IO_CHECK_CQ_DROPPED_BIT,
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};
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static inline bool io_has_work(struct io_ring_ctx *ctx)
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{
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return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
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!llist_empty(&ctx->work_llist);
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}
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#endif
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