Merge tag 'for-7.1/io_uring-20260411' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux

Pull io_uring updates from Jens Axboe:

- Add a callback driven main loop for io_uring, and BPF st

Merge tag 'for-7.1/io_uring-20260411' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux

Pull io_uring updates from Jens Axboe:

- Add a callback driven main loop for io_uring, and BPF struct_ops
on top to allow implementing custom event loop logic

- Decouple IOPOLL from being a ring-wide all-or-nothing setting,
allowing IOPOLL use cases to also issue certain white listed
non-polled opcodes

- Timeout improvements. Migrate internal timeout storage from
timespec64 to ktime_t for simpler arithmetic and avoid copying of
timespec data

- Zero-copy receive (zcrx) updates:

- Add a device-less mode (ZCRX_REG_NODEV) for testing and
experimentation where data flows through the copy fallback path

- Fix two-step unregistration regression, DMA length calculations,
xarray mark usage, and a potential 32-bit overflow in id
shifting

- Refactoring toward multi-area support: dedicated refill queue
struct, consolidated DMA syncing, netmem array refilling format,
and guard-based locking

- Zero-copy transmit (zctx) cleanup:

- Unify io_send_zc() and io_sendmsg_zc() into a single function

- Add vectorized registered buffer send for IORING_OP_SEND_ZC

- Add separate notification user_data via sqe->addr3 so
notification and completion CQEs can be distinguished without
extra reference counting

- Switch struct io_ring_ctx internal bitfields to explicit flag bits
with atomic-safe accessors, and annotate the known harmless races on
those flags

- Various optimizations caching ctx and other request fields in local
variables to avoid repeated loads, and cleanups for tctx setup, ring
fd registration, and read path early returns

* tag 'for-7.1/io_uring-20260411' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (58 commits)
io_uring: unify getting ctx from passed in file descriptor
io_uring/register: don't get a reference to the registered ring fd
io_uring/tctx: clean up __io_uring_add_tctx_node() error handling
io_uring/tctx: have io_uring_alloc_task_context() return tctx
io_uring/timeout: use 'ctx' consistently
io_uring/rw: clean up __io_read() obsolete comment and early returns
io_uring/zcrx: use correct mmap off constants
io_uring/zcrx: use dma_len for chunk size calculation
io_uring/zcrx: don't clear not allocated niovs
io_uring/zcrx: don't use mark0 for allocating xarray
io_uring: cast id to u64 before shifting in io_allocate_rbuf_ring()
io_uring/zcrx: reject REG_NODEV with large rx_buf_size
io_uring/cancel: validate opcode for IORING_ASYNC_CANCEL_OP
io_uring/rsrc: use io_cache_free() to free node
io_uring/zcrx: rename zcrx [un]register functions
io_uring/zcrx: check ctrl op payload struct sizes
io_uring/zcrx: cache fallback availability in zcrx ctx
io_uring/zcrx: warn on a repeated area append
io_uring/zcrx: consolidate dma syncing
io_uring/zcrx: netmem array as refiling format
...

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io_uring: introduce callback driven main loop

The io_uring_enter() has a fixed order of execution: it submits
requests, waits for completions, and returns to the user. Allow to
optionally replace it

io_uring: introduce callback driven main loop

The io_uring_enter() has a fixed order of execution: it submits
requests, waits for completions, and returns to the user. Allow to
optionally replace it with a custom loop driven by a callback called
loop_step. The basic requirements to the callback is that it should be
able to submit requests, wait for completions, parse them and repeat.
Most of the communication including parameter passing can be implemented
via shared memory.

The callback should return IOU_LOOP_CONTINUE to continue execution or
IOU_LOOP_STOP to return to the user space. Note that the kernel may
decide to prematurely terminate it as well, e.g. in case the process was
signalled or killed.

The hook takes a structure with parameters. It can be used to ask the
kernel to wait for CQEs by setting cq_wait_idx to the CQE index it wants
to wait for. Spurious wake ups are possible and even likely, the callback
is expected to handle it. There will be more parameters in the future
like timeout.

It can be used with kernel callbacks, for example, as a slow path
deprecation mechanism overwiting SQEs and emulating the wanted
behaviour, however it's more useful together with BPF programs
implemented in following patches.

Note that keeping it separately from the normal io_uring wait loop
makes things much simpler and cleaner. It keeps it in one place instead
of spreading a bunch of checks in different places including disabling
the submission path. It holds the lock by default, which is a better fit
for BPF synchronisation and the loop execution model. It nicely avoids
existing quirks like forced wake ups on timeout request completion. And
it should be easier to implement new features.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/a2d369aa1c9dd23ad7edac9220cffc563abcaed6.1772109579.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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