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https://github.com/torvalds/linux
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576cce9148
With the tctx fallback running its entries directly, the per-ctx fallback work has a single user left: moving local (DEFER_TASKRUN) task_work entries out of a ring that is going away. Both of its call sites are process context and don't hold ->uring_lock, the same conditions the deferred fallback work itself ran under - so run the entries in cancel mode right there instead, and rename the helper to io_cancel_local_task_work() to match what it now does. With that, ->fallback_llist, ->fallback_work, io_fallback_req_func() and __io_fallback_tw() can all go away, along with the fallback work flushing in the ring exit and cancel paths. Requests that get orphaned by an exiting task now run via the tctx fallback work, which the ring exit side implicitly waits on through the ctx refs those requests hold. Signed-off-by: Jens Axboe <axboe@kernel.dk>
118 lines
3.2 KiB
C
118 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef IOU_TW_H
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#define IOU_TW_H
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#include <linux/sched.h>
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#include <linux/percpu-refcount.h>
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#include <linux/io_uring_types.h>
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#include "mpscq.h"
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#define IO_LOCAL_TW_DEFAULT_MAX 20
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/*
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* Terminate the request if either of these conditions are true:
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*
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* 1) It's being executed by the original task, but that task is marked
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* with PF_EXITING as it's exiting.
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* 2) PF_KTHREAD is set, in which case the invoker of the task_work is
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* our fallback task_work.
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* 3) The ring has been closed and is going away.
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*/
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static inline bool io_should_terminate_tw(struct io_ring_ctx *ctx)
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{
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return (current->flags & (PF_EXITING | PF_KTHREAD)) || percpu_ref_is_dying(&ctx->refs);
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}
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void io_req_task_work_add_remote(struct io_kiocb *req, unsigned flags);
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void tctx_task_work(struct callback_head *cb);
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void io_tctx_fallback_work(struct work_struct *work);
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int io_run_local_work(struct io_ring_ctx *ctx, int min_events, int max_events);
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int io_run_task_work_sig(struct io_ring_ctx *ctx);
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__cold void io_cancel_local_task_work(struct io_ring_ctx *ctx);
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int io_run_local_work_locked(struct io_ring_ctx *ctx, int min_events);
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void io_req_local_work_add(struct io_kiocb *req, unsigned flags);
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void io_req_normal_work_add(struct io_kiocb *req);
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void tctx_task_work_run(struct io_uring_task *tctx, unsigned int max_entries, unsigned int *count);
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static inline void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
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{
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if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN)
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io_req_local_work_add(req, flags);
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else
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io_req_normal_work_add(req);
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}
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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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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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__set_current_state(TASK_RUNNING);
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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_local_work_pending(struct io_ring_ctx *ctx)
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{
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return !mpscq_empty(&ctx->work_list);
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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) || io_local_work_pending(ctx);
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}
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static inline void io_tw_lock(struct io_ring_ctx *ctx, io_tw_token_t tw)
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{
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lockdep_assert_held(&ctx->uring_lock);
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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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#endif
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