Commit Graph

68 Commits

Author SHA1 Message Date
Pavel Begunkov f26cc95935 io_uring: lockdep annotate CQ locking
Locking around CQE posting is complex and depends on options the ring is
created with, add more thorough lockdep annotations checking all
invariants.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/aa3770b4eacae3915d782cc2ab2f395a99b4b232.1672795976.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-01-03 19:05:41 -07:00
Jens Axboe 6434ec0186 io_uring: don't use TIF_NOTIFY_SIGNAL to test for availability of task_work
Use task_work_pending() as a better test for whether we have task_work
or not, TIF_NOTIFY_SIGNAL is only valid if the any of the task_work
items had been queued with TWA_SIGNAL as the notification mechanism.
Hence task_work_pending() is a more reliable check.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-17 13:40:17 -07:00
Pavel Begunkov 6971253f07 io_uring: revise completion_lock locking
io_kill_timeouts() doesn't post any events but queues everything to
task_work. Locking there is needed for protecting linked requests
traversing, we should grab completion_lock directly instead of using
io_cq_[un]lock helpers. Same goes for __io_req_find_next_prep().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/88e75d481a65dc295cb59722bb1cf76402d1c06b.1670002973.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-14 08:53:04 -07:00
Pavel Begunkov f66f73421f io_uring: skip spinlocking for ->task_complete
->task_complete was added to serialised CQE posting by doing it from
the task context only (or fallback wq when the task is dead), and now we
can use that to avoid taking ->completion_lock while filling CQ entries.
The patch skips spinlocking only in two spots,
__io_submit_flush_completions() and flushing in io_aux_cqe, it's safer
and covers all cases we care about. Extra care is taken to force taking
the lock while queueing overflow entries.

It fundamentally relies on SINGLE_ISSUER to have only one task posting
events. It also need to take into account overflowed CQEs, flushing of
which happens in the cq wait path, and so this implementation also needs
DEFER_TASKRUN to limit waiters. For the same reason we disable it for
SQPOLL, and for IOPOLL as it won't benefit from it in any case.
DEFER_TASKRUN, SQPOLL and IOPOLL requirement may be relaxed in the
future.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2a8c91fd82cfcdcc1d2e5bac7051fe2c183bda73.1670384893.git.asml.silence@gmail.com
[axboe: modify to apply]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-07 08:51:08 -07:00
Pavel Begunkov 618d653a34 io_uring: don't raw spin unlock to match cq_lock
There is one newly added place when we lock ring with io_cq_lock() but
unlocking is hand coded calling spin_unlock directly. It's ugly and
troublesome in the long run. Make it consistent with the other completion
locking.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4ca4f0564492b90214a190cd5b2a6c76522de138.1669821213.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30 10:28:49 -07:00
Jens Axboe b2cf789f6c Merge branch 'for-6.2/io_uring' into for-6.2/io_uring-next
* for-6.2/io_uring: (41 commits)
  io_uring: keep unlock_post inlined in hot path
  io_uring: don't use complete_post in kbuf
  io_uring: spelling fix
  io_uring: remove io_req_complete_post_tw
  io_uring: allow multishot polled reqs to defer completion
  io_uring: remove overflow param from io_post_aux_cqe
  io_uring: add lockdep assertion in io_fill_cqe_aux
  io_uring: make io_fill_cqe_aux static
  io_uring: add io_aux_cqe which allows deferred completion
  io_uring: allow defer completion for aux posted cqes
  io_uring: defer all io_req_complete_failed
  io_uring: always lock in io_apoll_task_func
  io_uring: remove iopoll spinlock
  io_uring: iopoll protect complete_post
  io_uring: inline __io_req_complete_put()
  io_uring: remove io_req_tw_post_queue
  io_uring: use io_req_task_complete() in timeout
  io_uring: hold locks for io_req_complete_failed
  io_uring: add completion locking for iopoll
  io_uring: kill io_cqring_ev_posted() and __io_cq_unlock_post()
  ...
2022-11-29 12:08:37 -07:00
Jens Axboe 7cfe7a0948 io_uring: clear TIF_NOTIFY_SIGNAL if set and task_work not available
With how task_work is added and signaled, we can have TIF_NOTIFY_SIGNAL
set and no task_work pending as it got run in a previous loop. Treat
TIF_NOTIFY_SIGNAL like get_signal(), always clear it if set regardless
of whether or not task_work is pending to run.

Cc: stable@vger.kernel.org
Fixes: 46a525e199 ("io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 10:55:08 -07:00
Dylan Yudaken 27f35fe909 io_uring: remove io_req_complete_post_tw
It's only used in one place. Inline it.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221125103412.1425305-2-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 06:10:46 -07:00
Dylan Yudaken b529c96a89 io_uring: remove overflow param from io_post_aux_cqe
The only call sites which would not allow overflow are also call sites
which would use the io_aux_cqe as they care about ordering.

So remove this parameter from io_post_aux_cqe.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-9-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 06:10:04 -07:00
Dylan Yudaken a77ab745f2 io_uring: make io_fill_cqe_aux static
This is only used in io_uring.c

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-7-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 06:10:04 -07:00
Dylan Yudaken 9b8c54755a io_uring: add io_aux_cqe which allows deferred completion
Use the just introduced deferred post cqe completion state when possible
in io_aux_cqe. If not possible fallback to io_post_aux_cqe.

This introduces a complication because of allow_overflow. For deferred
completions we cannot know without locking the completion_lock if it will
overflow (and even if we locked it, another post could sneak in and cause
this cqe to be in overflow).
However since overflow protection is mostly a best effort defence in depth
to prevent infinite loops of CQEs for poll, just checking the overflow bit
is going to be good enough and will result in at most 16 (array size of
deferred cqes) overflows.

Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-6-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 06:10:04 -07:00
Dylan Yudaken 973fc83f3a io_uring: defer all io_req_complete_failed
All failures happen under lock now, and can be deferred. To be consistent
when the failure has happened after some multishot cqe has been
deferred (and keep ordering), always defer failures.

To make this obvious at the caller (and to help prevent a future bug)
rename io_req_complete_failed to io_req_defer_failed.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221124093559.3780686-4-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25 06:10:04 -07:00
Pavel Begunkov 1bec951c38 io_uring: iopoll protect complete_post
io_req_complete_post() may be used by iopoll enabled rings, grab locks
in this case. That requires to pass issue_flags to propagate the locking
state.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/cc6d854065c57c838ca8e8806f707a226b70fd2d.1669203009.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23 10:45:31 -07:00
Pavel Begunkov 833b5dfffc io_uring: remove io_req_tw_post_queue
Remove io_req_tw_post() and io_req_tw_post_queue(), we can use
io_req_task_complete() instead.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b9b73c08022c7f1457023ac841f35c0100e70345.1669203009.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23 10:44:00 -07:00
Jens Axboe 4464853277 io_uring: pass in EPOLL_URING_WAKE for eventfd signaling and wakeups
Pass in EPOLL_URING_WAKE when signaling eventfd or doing poll related
wakups, so that we can check for a circular event dependency between
eventfd and epoll. If this flag is set when our wakeup handlers are
called, then we know we have a dependency that needs to terminate
multishot requests.

eventfd and epoll are the only such possible dependencies.

Cc: stable@vger.kernel.org # 6.0
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-22 06:08:31 -07:00
Pavel Begunkov f9d567c75e io_uring: inline __io_req_complete_post()
There is only one user of __io_req_complete_post(), inline it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ef4c9059950a3da5cf68df00f977f1fd13bd9306.1668597569.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21 07:45:19 -07:00
Pavel Begunkov e52d2e583e io_uring: inline io_req_task_work_add()
__io_req_task_work_add() is huge but marked inline, that makes compilers
to generate lots of garbage. Inline the wrapper caller
io_req_task_work_add() instead.

before and after:
   text    data     bss     dec     hex filename
  47347   16248       8   63603    f873 io_uring/io_uring.o
   text    data     bss     dec     hex filename
  45303   16248       8   61559    f077 io_uring/io_uring.o

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/26dc8c28ca0160e3269ef3e55c5a8b917c4d4450.1668162751.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21 07:44:18 -07:00
Pavel Begunkov 9148286476 io_uring: fix multishot accept request leaks
Having REQ_F_POLLED set doesn't guarantee that the request is
executed as a multishot from the polling path. Fortunately for us, if
the code thinks it's multishot issue when it's not, it can only ask to
skip completion so leaking the request. Use issue_flags to mark
multipoll issues.

Cc: stable@vger.kernel.org
Fixes: 390ed29b5e ("io_uring: add IORING_ACCEPT_MULTISHOT for accept")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7700ac57653f2823e30b34dc74da68678c0c5f13.1668710222.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-17 12:33:33 -07:00
Dylan Yudaken b3026767e1 io_uring: unlock if __io_run_local_work locked inside
It is possible for tw to lock the ring, and this was not propogated out to
io_run_local_work. This can cause an unlock to be missed.

Instead pass a pointer to locked into __io_run_local_work.

Fixes: 8ac5d85a89 ("io_uring: add local task_work run helper that is entered locked")
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20221027144429.3971400-3-dylany@meta.com
[axboe: WARN_ON() -> WARN_ON_ONCE() and add a minor comment]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-27 09:52:12 -06:00
Pavel Begunkov 44f87745d5 io_uring: optimise locking for local tw with submit_wait
Running local task_work requires taking uring_lock, for submit + wait we
can try to run them right after submit while we still hold the lock and
save one lock/unlokc pair. The optimisation was implemented in the first
local tw patches but got dropped for simplicity.

Suggested-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/281fc79d98b5d91fe4778c5137a17a2ab4693e5c.1665088876.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-12 16:30:56 -06:00
Pavel Begunkov fc86f9d3bb io_uring: remove redundant memory barrier in io_req_local_work_add
io_cqring_wake() needs a barrier for the waitqueue_active() check.
However, in the case of io_req_local_work_add(), we call llist_add()
first, which implies an atomic. Hence we can replace smb_mb() with
smp_mb__after_atomic().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/43983bc8bc507172adda7a0f00cab1aff09fd238.1665018309.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-12 16:30:56 -06:00
Jens Axboe 46a525e199 io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL
This isn't a reliable mechanism to tell if we have task_work pending, we
really should be looking at whether we have any items queued. This is
problematic if forward progress is gated on running said task_work. One
such example is reading from a pipe, where the write side has been closed
right before the read is started. The fput() of the file queues TWA_RESUME
task_work, and we need that task_work to be run before ->release() is
called for the pipe. If ->release() isn't called, then the read will sit
forever waiting on data that will never arise.

Fix this by io_run_task_work() so it checks if we have task_work pending
rather than rely on TIF_NOTIFY_SIGNAL for that. The latter obviously
doesn't work for task_work that is queued without TWA_SIGNAL.

Reported-by: Christiano Haesbaert <haesbaert@haesbaert.org>
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/665
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-29 16:07:45 -06:00
Pavel Begunkov aa1df3a360 io_uring: fix CQE reordering
Overflowing CQEs may result in reordering, which is buggy in case of
links, F_MORE and so on. If we guarantee that we don't reorder for
the unlikely event of a CQ ring overflow, then we can further extend
this to not have to terminate multishot requests if it happens. For
other operations, like zerocopy sends, we have no choice but to honor
CQE ordering.

Reported-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ec3bc55687b0768bbe20fb62d7d06cfced7d7e70.1663892031.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-23 15:04:20 -06:00
Pavel Begunkov 6567506b68 io_uring: disallow defer-tw run w/ no submitters
We try to restrict CQ waiters when IORING_SETUP_DEFER_TASKRUN is set,
but if nothing has been submitted yet it'll allow any waiter, which
violates the contract.

Fixes: c0e0d6ba25 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/b4f0d3f14236d7059d08c5abe2661ef0b78b5528.1662652536.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 13:14:55 -06:00
Pavel Begunkov 76de6749d1 io_uring: further limit non-owner defer-tw cq waiting
In case of DEFER_TASK_WORK we try to restrict waiters to only one task,
which is also the only submitter; however, we don't do it reliably,
which might be very confusing and backfire in the future. E.g. we
currently allow multiple tasks in io_iopoll_check().

Fixes: c0e0d6ba25 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/94c83c0a7fe468260ee2ec31bdb0095d6e874ba2.1662652536.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 13:14:46 -06:00
Jens Axboe dac6a0eae7 io_uring: ensure iopoll runs local task work as well
Combine the two checks we have for task_work running and whether or not
we need to shuffle the mutex into one, so we unify how task_work is run
in the iopoll loop. This helps ensure that local task_work is run when
needed, and also optimizes that path to avoid a mutex shuffle if it's
not needed.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 10:30:43 -06:00
Jens Axboe 8ac5d85a89 io_uring: add local task_work run helper that is entered locked
We have a few spots that drop the mutex just to run local task_work,
which immediately tries to grab it again. Add a helper that just passes
in whether we're locked already.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 10:30:43 -06:00
Dylan Yudaken c0e0d6ba25 io_uring: add IORING_SETUP_DEFER_TASKRUN
Allow deferring async tasks until the user calls io_uring_enter(2) with
the IORING_ENTER_GETEVENTS flag. Enable this mode with a flag at
io_uring_setup time. This functionality requires that the later
io_uring_enter will be called from the same submission task, and therefore
restrict this flag to work only when IORING_SETUP_SINGLE_ISSUER is also
set.

Being able to hand pick when tasks are run prevents the problem where
there is current work to be done, however task work runs anyway.

For example, a common workload would obtain a batch of CQEs, and process
each one. Interrupting this to additional taskwork would add latency but
not gain anything. If instead task work is deferred to just before more
CQEs are obtained then no additional latency is added.

The way this is implemented is by trying to keep task work local to a
io_ring_ctx, rather than to the submission task. This is required, as the
application will want to wake up only a single io_ring_ctx at a time to
process work, and so the lists of work have to be kept separate.

This has some other benefits like not having to check the task continually
in handle_tw_list (and potentially unlocking/locking those), and reducing
locks in the submit & process completions path.

There are networking cases where using this option can reduce request
latency by 50%. For example a contrived example using [1] where the client
sends 2k data and receives the same data back while doing some system
calls (to trigger task work) shows this reduction. The reason ends up
being that if sending responses is delayed by processing task work, then
the client side sits idle. Whereas reordering the sends first means that
the client runs it's workload in parallel with the local task work.

[1]:
Using https://github.com/DylanZA/netbench/tree/defer_run
Client:
./netbench  --client_only 1 --control_port 10000 --host <host> --tx "epoll --threads 16 --per_thread 1 --size 2048 --resp 2048 --workload 1000"
Server:
./netbench  --server_only 1 --control_port 10000  --rx "io_uring --defer_taskrun 0 --workload 100"   --rx "io_uring  --defer_taskrun 1 --workload 100"

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220830125013.570060-5-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 10:30:42 -06:00
Pavel Begunkov bd1a3783dd io_uring: export req alloc from core
We want to do request allocation out of the core io_uring code, make the
allocation functions public for other io_uring parts.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0314fedd3a02a514210ba42d4720332538c65956.1658913593.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-27 08:50:50 -06:00
Pavel Begunkov 63809137eb io_uring: flush notifiers after sendzc
Allow to flush notifiers as a part of sendzc request by setting
IORING_SENDZC_FLUSH flag. When the sendzc request succeedes it will
flush the used [active] notifier.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e0b4d9a6797e2fd6092824fe42953db7a519bbc8.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:41:07 -06:00
Pavel Begunkov eb42cebb2c io_uring: add zc notification infrastructure
Add internal part of send zerocopy notifications. There are two main
structures, the first one is struct io_notif, which carries inside
struct ubuf_info and maps 1:1 to it. io_uring will be binding a number
of zerocopy send requests to it and ask to complete (aka flush) it. When
flushed and all attached requests and skbs complete, it'll generate one
and only one CQE. There are intended to be passed into the network layer
as struct msghdr::msg_ubuf.

The second concept is notification slots. The userspace will be able to
register an array of slots and subsequently addressing them by the index
in the array. Slots are independent of each other. Each slot can have
only one notifier at a time (called active notifier) but many notifiers
during the lifetime. When active, a notifier not going to post any
completion but the userspace can attach requests to it by specifying
the corresponding slot while issueing send zc requests. Eventually, the
userspace will want to "flush" the notifier losing any way to attach
new requests to it, however it can use the next atomatically added
notifier of this slot or of any other slot.

When the network layer is done with all enqueued skbs attached to a
notifier and doesn't need the specified in them user data, the flushed
notifier will post a CQE.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3ecf54c31a85762bf679b0a432c9f43ecf7e61cc.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:41:06 -06:00
Pavel Begunkov e70cb60893 io_uring: export io_put_task()
Make io_put_task() available to non-core parts of io_uring, we'll need
it for notification infrastructure.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3686807d4c03b72e389947b0e8692d4d44334ef0.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:41:06 -06:00
Jens Axboe f6b543fd03 io_uring: ensure REQ_F_ISREG is set async offload
If we're offloading requests directly to io-wq because IOSQE_ASYNC was
set in the sqe, we can miss hashing writes appropriately because we
haven't set REQ_F_ISREG yet. This can cause a performance regression
with buffered writes, as io-wq then no longer correctly serializes writes
to that file.

Ensure that we set the flags in io_prep_async_work(), which will cause
the io-wq work item to be hashed appropriately.

Fixes: 584b0180f0 ("io_uring: move read/write file prep state into actual opcode handler")
Link: https://lore.kernel.org/io-uring/20220608080054.GB22428@xsang-OptiPlex-9020/
Reported-by: kernel test robot <oliver.sang@intel.com>
Tested-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:18 -06:00
Dylan Yudaken e0486f3f7c io_uring: only trace one of complete or overflow
In overflow we see a duplcate line in the trace, and in some cases 3
lines (if initial io_post_aux_cqe fails).
Instead just trace once for each CQE

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-13-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:17 -06:00
Dylan Yudaken 52120f0fad io_uring: add allow_overflow to io_post_aux_cqe
Some use cases of io_post_aux_cqe would not want to overflow as is, but
might want to change the flags/result. For example multishot receive
requires in order CQE, and so if there is an overflow it would need to
stop receiving until the overflow is taken care of.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-8-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:17 -06:00
Dylan Yudaken 114eccdf0e io_uring: add IOU_STOP_MULTISHOT return code
For multishot we want a way to signal the caller that multishot has ended
but also this might not be an error return.

For example sockets return 0 when closed, which should end a multishot
recv, but still have a CQE with result 0

Introduce IOU_STOP_MULTISHOT which does this and indicates that the return
code is stored inside req->cqe

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-7-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:17 -06:00
Dylan Yudaken ed5ccb3bee io_uring: remove priority tw list optimisation
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>
2022-07-24 18:39:15 -06:00
Pavel Begunkov a6b21fbb4c io_uring: move list helpers to a separate file
It's annoying to have io-wq.h as a dependency every time we want some of
struct io_wq_work_list helpers, move them into a separate file.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c1d891ce12b30767d1d2a3b7db2ca3abc1ecc4a2.1655802465.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:15 -06:00
Pavel Begunkov 625d38b3fd io_uring: improve io_run_task_work()
Since SQPOLL now uses TWA_SIGNAL_NO_IPI, there won't be task work items
without TIF_NOTIFY_SIGNAL. Simplify io_run_task_work() by removing
task->task_works check. Even though looks it doesn't cause extra cache
bouncing, it's still nice to not touch it an extra time when it might be
not cached.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/75d4f34b0c671075892821a409e28da6cb1d64fe.1655802465.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:15 -06:00
Pavel Begunkov 9da070b142 io_uring: consistent naming for inline completion
Improve naming of the inline/deferred completion helper so it's
consistent with it's *_post counterpart. Add some comments and extra
lockdeps to ensure the locking is done right.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/797c619943dac06529e9d3fcb16e4c3cde6ad1a3.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:15 -06:00
Pavel Begunkov 46929b0868 io_uring: add io_commit_cqring_flush()
Since __io_commit_cqring_flush users moved to different files, introduce
io_commit_cqring_flush() helper and encapsulate all flags testing details
inside.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0da03887435dd9869ffe46dcd3962bf104afcca3.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:15 -06:00
Pavel Begunkov 253993210b io_uring: introduce locking helpers for CQE posting
spin_lock(&ctx->completion_lock);
/* post CQEs */
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
io_cqring_ev_posted(ctx);

We have many places repeating this sequence, and the three function
unlock section is not perfect from the maintainance perspective and also
makes it harder to add new locking/sync trick.

Introduce two helpers. io_cq_lock(), which is simple and only grabs
->completion_lock, and io_cq_unlock_post() encapsulating the three call
section.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fe0c682bf7f7b55d9be55b0d034be9c1949277dc.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov d9dee4302a io_uring: remove ->flush_cqes optimisation
It's not clear how widely used IOSQE_CQE_SKIP_SUCCESS is, and how often
->flush_cqes flag prevents from completion being flushed. Sometimes it's
high level of concurrency that enables it at least for one CQE, but
sometimes it doesn't save much because nobody waiting on the CQ.

Remove ->flush_cqes flag and the optimisation, it should benefit the
normal use case. Note, that there is no spurious eventfd problem with
that as checks for spuriousness were incorporated into
io_eventfd_signal().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/692e81eeddccc096f449a7960365fa7b4a18f8e6.1655637157.git.asml.silence@gmail.com
[axboe: remove now dead state->flush_cqes variable]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov 9046c6415b io_uring: reshuffle io_uring/io_uring.h
It's a good idea to first do forward declarations and then inline
helpers, otherwise there will be keep stumbling on dependencies
between them.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1d7fa6672ed43f20ccc0c54ae201369ebc3ebfab.1655637157.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov ab1c84d855 io_uring: make io_uring_types.h public
Move io_uring types to linux/include, need them public so tracing can
see the definitions and we can clean trace/events/io_uring.h

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a15f12e8cb7289b2de0deaddcc7518d98a132d17.1655384063.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov b3659a65be io_uring: change ->cqe_cached invariant for CQE32
With IORING_SETUP_CQE32 ->cqe_cached doesn't store a real address but
rather an implicit offset into cqes. Store the real cqe pointer and
increment it accordingly if CQE32.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1ee1838cba16bed96381a006950b36ba640d998c.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov e8c328c391 io_uring: deduplicate io_get_cqe() calls
Deduplicate calls to io_get_cqe() from __io_fill_cqe_req().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4fa077986cc3abab7c59ff4e7c390c783885465f.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov ae5735c69b io_uring: deduplicate __io_fill_cqe_req tracing
Deduplicate two trace_io_uring_complete() calls in __io_fill_cqe_req().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/277ed85dba5189ab7d932164b314013a0f0b0fdc.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov 68494a65d0 io_uring: introduce io_req_cqe_overflow()
__io_fill_cqe_req() is hot and inlined, we want it to be as small as
possible. Add io_req_cqe_overflow() accepting only a request and doing
all overflow accounting, and replace with it two calls to 6 argument
io_cqring_event_overflow().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/048b9fbcce56814d77a1a540409c98c3d383edcb.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00
Pavel Begunkov faf88dde06 io_uring: don't inline __io_get_cqe()
__io_get_cqe() is not as hot as io_get_cqe(), no need to inline it, it
sheds ~500B from the binary.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c1ac829198a881b7af8710926f99a3559b9f24c0.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:14 -06:00