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Add a new flag IORING_REGISTER_USE_REGISTERED_RING (set via the high bit
of the opcode) to treat the fd as a registered index rather than a file
descriptor.
This makes it possible for a library to open an io_uring, register the
ring fd, close the ring fd, and subsequently use the ring entirely via
registered index.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: https://lore.kernel.org/r/f2396369e638284586b069dbddffb8c992afba95.1676419314.git.josh@joshtriplett.org
[axboe: remove extra high bit clear]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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REQ_F_FORCE_ASYNC was being ignored for re-queueing linked
requests. Instead obey that flag.
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20230127135227.3646353-2-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If CONFIG_PREEMPT_NONE is set and the task_work chains are long, we
could be running into issues blocking others for too long. Add a
reschedule check in handle_tw_list(), and flush the ctx if we need to
reschedule.
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If the kernel is configured with CONFIG_PREEMPT_NONE, we could be
sitting in a tight loop reaping events but not giving them a chance to
finish. This results in a trace ala:
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 2-...!: (5249 ticks this GP) idle=935c/1/0x4000000000000000 softirq=4265/4274 fqs=1
(t=5251 jiffies g=465 q=4135 ncpus=4)
rcu: rcu_sched kthread starved for 5249 jiffies! g465 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_sched state:R running task stack:0 pid:12 ppid:2 flags:0x00000008
Call trace:
__switch_to+0xb0/0xc8
__schedule+0x43c/0x520
schedule+0x4c/0x98
schedule_timeout+0xbc/0xdc
rcu_gp_fqs_loop+0x308/0x344
rcu_gp_kthread+0xd8/0xf0
kthread+0xb8/0xc8
ret_from_fork+0x10/0x20
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 0:
task:kworker/u8:10 state:R running task stack:0 pid:89 ppid:2 flags:0x0000000a
Workqueue: events_unbound io_ring_exit_work
Call trace:
__switch_to+0xb0/0xc8
0xffff0000c8fefd28
CPU: 2 PID: 95 Comm: kworker/u8:13 Not tainted 6.2.0-rc5-00042-g40316e337c80-dirty #2759
Hardware name: linux,dummy-virt (DT)
Workqueue: events_unbound io_ring_exit_work
pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : io_do_iopoll+0x344/0x360
lr : io_do_iopoll+0xb8/0x360
sp : ffff800009bebc60
x29: ffff800009bebc60 x28: 0000000000000000 x27: 0000000000000000
x26: ffff0000c0f67d48 x25: ffff0000c0f67840 x24: ffff800008950024
x23: 0000000000000001 x22: 0000000000000000 x21: ffff0000c27d3200
x20: ffff0000c0f67840 x19: ffff0000c0f67800 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000001 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000179 x10: 0000000000000870 x9 : ffff800009bebd60
x8 : ffff0000c27d3ad0 x7 : fefefefefefefeff x6 : 0000646e756f626e
x5 : ffff0000c0f67840 x4 : 0000000000000000 x3 : ffff0000c2398000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
io_do_iopoll+0x344/0x360
io_uring_try_cancel_requests+0x21c/0x334
io_ring_exit_work+0x90/0x40c
process_one_work+0x1a4/0x254
worker_thread+0x1ec/0x258
kthread+0xb8/0xc8
ret_from_fork+0x10/0x20
Add a cond_resched() in the cancelation IOPOLL loop to fix this.
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_submit_flush_completions() may produce new task_work items, so it's a
good idea to recheck the task_work list after flushing completions. The
optimisation is not new and was accidentially removed by
f88262e60bb9 ("io_uring: lockless task list")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a7ed5ede84de190832cc33ebbcdd6e91cd90f5b6.1674484266.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge almost identical sections of tctx_task_work(), this will make code
modifications later easier and also inlines handle_tw_list().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d06592d91e3e7559e7a4dbb8907d110863008dc7.1674484266.git.asml.silence@gmail.com
[axboe: fold in setting count to zero patch from Tom Rix]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a helper for putting refs from the target task context, rename
__io_put_task() and add a couple of comments around. Use the remote
version for __io_req_complete_post(), the local is only needed for
__io_submit_flush_completions().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3bf92ebd594769d8a5d648472a8e335f2031d542.1674484266.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Follow the io_get_sqe pattern returning the result via a pointer
and hide request cache refill inside io_alloc_req().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8c37c2e8a3cb5e4cd6a8ae3b91371227a92708a6.1674484266.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Return an SQE from io_get_sqe() as a parameter and use the return value
to determine if it failed or not. This enables the compiler to compile out
the sqe NULL check when we know that the return SQE is valid.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9cceb11329240ea097dffef6bf0a675bca14cf42.1674484266.git.asml.silence@gmail.com
[axboe: remove bogus const modifier on return value]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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__io_cqring_overflow_flush() doesn't return anything anymore, remove
outdate comment.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4ce2bcbb17eac80cdf883fd1459d5ee6586e238c.1674484266.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We return POLLIN from io_uring_poll() depending on whether there are
CQEs for the userspace, and so we should use the user visible tail
pointer instead of a transient cached value.
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/228ffcbf30ba98856f66ffdb9a6a60ead1dd96c0.1674484266.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This generates better code for me, avoiding an extra load on arm64, and
both call sites already have this variable available for easy passing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Every io_uring request is represented by struct io_kiocb, which is
cached locally by io_uring (not SLAB/SLUB) in the list called
submit_state.freelist. This patch simply enabled KASAN for this free
list.
This list is initially created by KMEM_CACHE, but later, managed by
io_uring. This patch basically poisons the objects that are not used
(i.e., they are the free list), and unpoisons it when the object is
allocated/removed from the list.
Touching these poisoned objects while in the freelist will cause a KASAN
warning.
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This patch removes some "cold" fields from `struct io_issue_def`.
The plan is to keep only highly used fields into `struct io_issue_def`, so,
it may be hot in the cache. The hot fields are basically all the bitfields
and the callback functions for .issue and .prep.
The other less frequently used fields are now located in a secondary and
cold struct, called `io_cold_def`.
This is the size for the structs:
Before: io_issue_def = 56 bytes
After: io_issue_def = 24 bytes; io_cold_def = 40 bytes
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230112144411.2624698-2-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The current io_op_def struct is becoming huge and the name is a bit
generic.
The goal of this patch is to rename this struct to `io_issue_def`. This
struct will contain the hot functions associated with the issue code
path.
For now, this patch only renames the structure, and an upcoming patch
will break up the structure in two, moving the non-issue fields to a
secondary struct.
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230112144411.2624698-1-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Keep parts of __io_req_complete_post() relying on req->flags together so
the value can be cached.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2b4fbb42f404a0e75c4d9f0a5b16f314a839d0a9.1673887636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Lock the ring with uring_lock in io_fallback_req_func(), which should
make it a bit safer and easier. With that we also don't need refs
pinning as io_ring_exit_work() will wait until uring_lock is freed.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/56170e6a0cbfc8edee2794c6613e8f6f1d76d276.1673887636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_put_task() is only used in uring.c so enclose it there together with
__io_put_task().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/43c7f9227e2ab215f1a6069dadbc5382bed346fe.1673887636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_submit_flush_completions() may queue new requests for tw execution,
especially true for linked requests. Recheck the tw list for emptiness
after flushing completions.
Note that this doesn't really fix the commit referenced below, but it
does reinstate an optimization that existed before that got merged.
Fixes: f88262e60bb9 ("io_uring: lockless task list")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6328acdbb5e60efc762b18003382de077e6e1367.1673887636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Change the return type to void since it always return 0, and no need
to do the checking in syscall io_uring_enter.
Signed-off-by: Quanfa Fu <quanfafu@gmail.com>
Link: https://lore.kernel.org/r/20230115071519.554282-1-quanfafu@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We needed fake nodes in __io_run_local_work() and to avoid unecessary wake
ups while the task already running task_works, but we don't need them
anymore since wake ups are protected by cq_waiting, which is always
cleared by the time we're executing deferred task_work items.
Note that because of loose sync around cq_waiting clearing
io_req_local_work_add() may wake the task more than once, but that's
fine and should be rare to not hurt perf.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8839534891f0a2f1076e78554a31ea7e099f7de5.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Don't wake the master task after queueing a deferred tw unless it's
currently waiting in io_cqring_wait.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/717702d772825a6647e6c315b4690277ba84c3fc.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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With DEFER_TASKRUN only ctx->submitter_task might be waiting for CQEs,
we can use this to optimise io_cqring_wait(). Replace ->cq_wait
waitqueue with waking the task directly.
It works but misses an important optimisation covered by the following
patch, so this patch without follow ups might hurt performance.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/103d174d35d919d4cb0922d8a9c93a8f0c35f74a.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Flush completions is done either from the submit syscall or by the
task_work, both are in the context of the submitter task, and when it
goes for a single threaded rings like implied by ->task_complete, there
won't be any waiters on ->cq_wait but the master task. That means that
there can be no tasks sleeping on cq_wait while we run
__io_submit_flush_completions() and so waking up can be skipped.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/60ad9768ec74435a0ddaa6eec0ffa7729474f69f.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Even though io_poll_wq_wake()'s waitqueue_active reuses a barrier we do
for another waitqueue, it's not going to be the case in the future and
so we want to have a fast path for it when the ring has never been
polled.
Move poll_wq wake ups into __io_commit_cqring_flush() using a new flag
called ->poll_activated. The idea behind the flag is to set it when the
ring was polled for the first time. This requires additional sync to not
miss events, which is done here by using task_work for ->task_complete
rings, and by default enabling the flag for all other types of rings.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/060785e8e9137a920b232c0c7f575b131af19cac.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Don't use ->cq_wait for ring polling but add a separate wait queue for
it. We need it for following patches.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/dea0be0bf990503443c5c6c337fc66824af7d590.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_run_local_work_locked() is only used in io_uring.c, move it there.
With that we can also make __io_run_local_work() static.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/91757bcb33e5774e49fed6f2b6e058630608119b.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_run_local_work is enclosed in io_uring.c, we don't need to export it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b477fb81f5e77044f724a06fe245d5c078659364.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The CQ waiting loop sets TASK_RUNNING before trying to execute
task_work, no need to repeat it in io_run_local_work().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9d9422c429ef3f9457b4f4b8288bf4789564f33b.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Remove a local variable ctx in io_wake_function(), we don't need it if
io_should_wake() triggers it to wake up.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e60eb1008aebe286aab7d34c772ed01c447bddb1.1673274244.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move waiting timeout into io_wait_queue
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e4b48a9e26a3b1cf97c80121e62d4b5ab873d28d.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Unlike the jiffy scheduling version, schedule_hrtimeout() jumps a few
functions before getting into schedule() even if there is no actual
timeout needed. Some tests showed that it takes up to 1% of CPU cycles.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/89f880574eceee6f4899783377ead234df7b3d04.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of constantly watching that the state of the task is running
before executing tw or taking locks in io_cqring_wait(), switch it back
to TASK_RUNNING immediately.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/246dddee247d89fd52023f785ed17cc34962a008.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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->work_llist should never be non-empty for a non DEFER_TASKRUN ring, so
we can safely skip checking the flag.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/26af9f73c09a56c9a035f94db56127358688f3aa.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_cqring_wait_schedule() is called after we started waiting on the cq
wq and set the state to TASK_INTERRUPTIBLE, for that reason we have to
constantly worry whether we has returned the state back to running or
not. Leave only quick checks in io_cqring_wait_schedule() and move the
rest including running task work to the callers. Note, we run tw in the
loop after the sched checks because of the fast path in the beginning of
the function.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2814fabe75e2e019e7ca43ea07daa94564349805.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We already avoid flushing overflows in io_cqring_wait_schedule() but
only return an error for the outer loop to handle it. Minimise it even
further by moving all ->check_cq parsing there.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9dfcec3121013f98208dbf79368d636d74e1231a.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Most places that want to run local tw explicitly and in advance check if
they are allowed to do so. Don't rely on a similar check in
__io_run_local_work(), leave it as a just-in-case warning and make sure
callers checks capabilities themselves.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/990fe0e8e70fd4d57e43625e5ce8fba584821d1a.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There is only one user of io_run_task_work_ctx(), inline it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/40953c65f7c88fb00cdc4d870ca5d5319fb3d7ea.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Task work runners keep running until all queues tw items are exhausted.
It's also rare for defer tw to queue normal tw and vise versa. Taking it
into account, there is only a dim chance that further iterating the
io_cqring_wait() fast path will get us anything and so we can remove
the loop there.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1f9565726661266abaa5d921e97433c831759ecf.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There should be nothing in the ->work_llist for non DEFER_TASKRUN rings,
so we can skip flag checks and test the list emptiness directly. Also
move it out of io_run_local_work() for inlining.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/331d63fd15ca79b35b95c82a82d9246110686392.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Drain requests all go through io_drain_req, which has a quick exit in case
there is nothing pending (ie the drain is not useful). In that case it can
run the issue the request immediately.
However for safety it queues it through task work.
The problem is that in this case the request is run asynchronously, but
the async work has not been prepared through io_req_prep_async.
This has not been a problem up to now, as the task work always would run
before returning to userspace, and so the user would not have a chance to
race with it.
However - with IORING_SETUP_DEFER_TASKRUN - this is no longer the case and
the work might be defered, giving userspace a chance to change data being
referred to in the request.
Instead _always_ prep_async for drain requests, which is simpler anyway
and removes this issue.
Cc: stable@vger.kernel.org
Fixes: c0e0d6ba25f1 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20230127105911.2420061-1-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IORING_SETUP_R_DISABLED rings don't have the submitter task set, so
it's not always safe to use ->submitter_task. Disallow posting msg_ring
messaged to disabled rings. Also add task NULL check for loosy sync
around testing for IORING_SETUP_R_DISABLED.
Cc: stable@vger.kernel.org
Fixes: 6d043ee1164ca ("io_uring: do msg_ring in target task via tw")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Jiffy to ktime CQ waiting conversion broke how we treat timeouts, in
particular we rearm it anew every time we get into
io_cqring_wait_schedule() without adjusting the timeout. Waiting for 2
CQEs and getting a task_work in the middle may double the timeout value,
or even worse in some cases task may wait indefinitely.
Cc: stable@vger.kernel.org
Fixes: 228339662b398 ("io_uring: don't convert to jiffies for waiting on timeouts")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f7bffddd71b08f28a877d44d37ac953ddb01590d.1672915663.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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>
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Unlike normal tw, nothing prevents deferred tw to be executed right
after an tw item added to ->work_llist in io_req_local_work_add(). For
instance, the waiting task may get waken up by CQ posting or a normal
tw. Thus we need to pin the ring for the rest of io_req_local_work_add()
Cc: stable@vger.kernel.org
Fixes: c0e0d6ba25f18 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1a79362b9c10b8523ef70b061d96523650a23344.1672795998.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We only check the register opcode value inside the restricted ring
section, move it into the main io_uring_register() function instead
and check it up front.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we have overflow entries being generated after we've done the
initial flush in io_cqring_wait(), then we could be flushing them in the
main wait loop as well. If that's done after having added ourselves
to the cq_wait waitqueue, then the task state can be != TASK_RUNNING
when we enter the overflow flush.
Check for the need to overflow flush, and finish our wait cycle first
if we have to do so.
Reported-and-tested-by: syzbot+cf6ea1d6bb30a4ce10b2@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/000000000000cb143a05f04eee15@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It's quite possible that we got woken up because task_work was queued,
and we need to process this task_work to generate the events waited for.
If we return to the wait loop without running task_work, we'll end up
adding the task to the waitqueue again, only to call
io_cqring_wait_schedule() again which will run the task_work. This is
less efficient than it could be, as it requires adding to the cq_wait
queue again. It also triggers the wakeup path for completions as
cq_wait is now non-empty with the task itself, and it'll require another
lock grab and deletion to remove ourselves from the waitqueue.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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io_uring uses call_rcu in the case it needs to signal an eventfd as a
result of an eventfd signal, since recursing eventfd signals are not
allowed. This should be calling the new call_rcu_hurry API to not delay
the signal.
Signed-off-by: Dylan Yudaken <dylany@meta.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20221215184138.795576-1-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Because the single task locking series got reordered ahead of the
timeout and completion lock changes, two hunks inadvertently ended up
using __io_fill_cqe_req() rather than io_fill_cqe_req(). This meant
that we dropped overflow handling in those two spots. Reinstate the
correct CQE filling helper.
Fixes: f66f73421f0a ("io_uring: skip spinlocking for ->task_complete")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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