99 lines
2.8 KiB
Groff
99 lines
2.8 KiB
Groff
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.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk>
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.\"
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.\" SPDX-License-Identifier: LGPL-2.0-or-later
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.\"
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.TH io_uring_prep_poll_timeout_update 3 "March 12, 2022" "liburing-2.2" "liburing Manual"
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.SH NAME
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io_uring_prep_timeoute_update \- prepare a request to update an existing timeout
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.SH SYNOPSIS
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.nf
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.B #include <liburing.h>
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.PP
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.BI "void io_uring_prep_timeout_update(struct io_uring_sqe *" sqe ","
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.BI " struct __kernel_timespec *" ts ","
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.BI " __u64 " user_data ","
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.BI " unsigned " flags ");"
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.PP
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.BI "void io_uring_prep_timeout_remove(struct io_uring_sqe *" sqe ","
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.BI " __u64 " user_data ","
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.BI " unsigned " flags ");"
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.fi
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.SH DESCRIPTION
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.PP
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These functions modify or cancel an existing timeout request. The submission
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queue entry
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.I sqe
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is setup to arm a timeout update or removal specified by
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.I user_data
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and with modifier flags given by
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.IR flags .
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Additionally, the update request includes a
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.I ts
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structure, which contains new timeout information.
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For an update request, the
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.I flags
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member may contain a bitmask of the following values:
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.TP
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.B IORING_TIMEOUT_ABS
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The value specified in
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.I ts
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is an absolute value rather than a relative one.
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.TP
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.B IORING_TIMEOUT_BOOTTIME
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The boottime clock source should be used.
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.TP
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.B IORING_TIMEOUT_REALTIME
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The realtime clock source should be used.
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.TP
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.B IORING_TIMEOUT_ETIME_SUCCESS
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Consider an expired timeout a success in terms of the posted completion.
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Normally a timeout that triggers would return in a
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.B -ETIME
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CQE
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.I res
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value.
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.PP
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.SH RETURN VALUE
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None
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.SH ERRORS
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These are the errors that are reported in the CQE
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.I res
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field. On success,
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.B 0
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is returned.
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.TP
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.B -ENOENT
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The timeout identified by
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.I user_data
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could not be found. It may be invalid, or triggered before the update or
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removal request was processed.
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.TP
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.B -EALREADY
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The timeout identified by
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.I user_data
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is already firing and cannot be canceled.
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.TP
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.B -EINVAL
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One of the fields set in the SQE was invalid. For example, two clocksources
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where given, or the specified timeout seconds or nanoseconds where < 0.
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.TP
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.B -EFAULT
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io_uring was unable to access the data specified by
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.IR ts .
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.SH NOTES
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As with any request that passes in data in a struct, that data must remain
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valid until the request has been successfully submitted. It need not remain
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valid until completion. Once a request has been submitted, the in-kernel
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state is stable. Very early kernels (5.4 and earlier) required state to be
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stable until the completion occurred. Applications can test for this
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behavior by inspecting the
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.B IORING_FEAT_SUBMIT_STABLE
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flag passed back from
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.BR io_uring_queue_init_params (3).
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.SH SEE ALSO
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.BR io_uring_get_sqe (3),
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.BR io_uring_submit (3),
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.BR io_uring_prep_timeout (3)
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