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194bb58c60
Add support for FUTEX_WAKE/WAIT primitives. IORING_OP_FUTEX_WAKE is mix of FUTEX_WAKE and FUTEX_WAKE_BITSET, as it does support passing in a bitset. Similary, IORING_OP_FUTEX_WAIT is a mix of FUTEX_WAIT and FUTEX_WAIT_BITSET. For both of them, they are using the futex2 interface. FUTEX_WAKE is straight forward, as those can always be done directly from the io_uring submission without needing async handling. For FUTEX_WAIT, things are a bit more complicated. If the futex isn't ready, then we rely on a callback via futex_queue->wake() when someone wakes up the futex. From that calback, we queue up task_work with the original task, which will post a CQE and wake it, if necessary. Cancelations are supported, both from the application point-of-view, but also to be able to cancel pending waits if the ring exits before all events have occurred. The return value of futex_unqueue() is used to gate who wins the potential race between cancelation and futex wakeups. Whomever gets a 'ret == 1' return from that claims ownership of the io_uring futex request. This is just the barebones wait/wake support. PI or REQUEUE support is not added at this point, unclear if we might look into that later. Likewise, explicit timeouts are not supported either. It is expected that users that need timeouts would do so via the usual io_uring mechanism to do that using linked timeouts. The SQE format is as follows: `addr` Address of futex `fd` futex2(2) FUTEX2_* flags `futex_flags` io_uring specific command flags. None valid now. `addr2` Value of futex `addr3` Mask to wake/wait Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
29 lines
721 B
C
29 lines
721 B
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef IORING_CANCEL_H
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#define IORING_CANCEL_H
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#include <linux/io_uring_types.h>
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struct io_cancel_data {
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struct io_ring_ctx *ctx;
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union {
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u64 data;
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struct file *file;
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};
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u8 opcode;
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u32 flags;
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int seq;
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};
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int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
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int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags);
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int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd,
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unsigned int issue_flags);
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void init_hash_table(struct io_hash_table *table, unsigned size);
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int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg);
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bool io_cancel_req_match(struct io_kiocb *req, struct io_cancel_data *cd);
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#endif
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