io_uring: restore back registered wait arguments

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Now we've got a more generic region registration API, place
IORING_ENTER_EXT_ARG_REG and re-enable it.

First, the user has to register a region with the
IORING_MEM_REGION_REG_WAIT_ARG flag set. It can only be done for a
ring in a disabled state, aka IORING_SETUP_R_DISABLED, to avoid races
with already running waiters. With that we should have stable constant
values for ctx->cq_wait_{size,arg} in io_get_ext_arg_reg() and hence no
READ_ONCE required.

The other API difference is that we're now passing byte offsets instead
of indexes. The user _must_ align all offsets / pointers to the native
word size, failing to do so might but not necessarily has to lead to a
failure usually returned as -EFAULT. liburing will be hiding this
details from users.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/81822c1b4ffbe8ad391b4f9ad1564def0d26d990.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Pavel Begunkov 2024-11-15 16:54:43 +00:00 • committed by Jens Axboe

parent 93238e6618

commit d617b3147d

4 changed files with 36 additions and 2 deletions

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3

include/linux/io_uring_types.h

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5

include/uapi/linux/io_uring.h

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14

io_uring/io_uring.c

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16

io_uring/register.c

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