With IORING_REGISTER_USE_REGISTERED_RING, an application can register
the ring fd and use it via registered index rather than installed fd.
This allows using a registered ring for everything *except* the initial
mmap.
With IORING_SETUP_NO_MMAP, io_uring_setup uses buffers allocated by the
user, rather than requiring a subsequent mmap.
The combination of the two allows a user to operate *entirely* via a
registered ring fd, making it unnecessary to ever install the fd in the
first place. So, add a flag IORING_SETUP_REGISTERED_FD_ONLY to make
io_uring_setup register the fd and return a registered index, without
installing the fd.
This allows an application to avoid touching the fd table at all, and
allows a library to never even momentarily install a file descriptor.
This splits out an io_ring_add_registered_file helper from
io_ring_add_registered_fd, for use by io_uring_setup.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: https://lore.kernel.org/r/bc8f431bada371c183b95a83399628b605e978a3.1682699803.git.josh@joshtriplett.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This better describes what it does - it's incremented when the task is
currently undergoing a cancelation operation, due to exiting or exec'ing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
this is no longer needed, as submitter_task is set at creation time.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Fixes: 97bbdc06a4 ("io_uring: add IORING_SETUP_SINGLE_ISSUER")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove submitter parameter from __io_uring_add_tctx_node.
It was only called from one place, and we can do that logic in that one
place.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Fixes: 97bbdc06a4 ("io_uring: add IORING_SETUP_SINGLE_ISSUER")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With networking use cases we see contention on the spinlock used to
protect the task_list when multiple threads try and add completions at once.
Instead we can use a lockless list, and assume that the first caller to
add to the list is responsible for kicking off task work.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220622134028.2013417-4-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This optimisation has some built in assumptions that make it easy to
introduce bugs. It also does not have clear wins that make it worth keeping.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220622134028.2013417-2-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new IORING_SETUP_SINGLE_ISSUER flag and the userspace visible part
of it, i.e. put limitations of submitters. Also, don't allow it together
with IOPOLL as we're not going to put it to good use.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4bcc41ee467fdf04c8aab8baf6ce3ba21858c3d4.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Josh Triplett