- 25 Jul, 2022 40 commits
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Dylan Yudaken authored
Make the trace format consistent with io_uring_complete for cflags Signed-off-by:
Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220630091231.1456789-12-dylany@fb.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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Dylan Yudaken authored
Support multishot receive for io_uring. Typical server applications will run a loop where for each recv CQE it requeues another recv/recvmsg. This can be simplified by using the existing multishot functionality combined with io_uring's provided buffers. The API is to add the IORING_RECV_MULTISHOT flag to the SQE. CQEs will then be posted (with IORING_CQE_F_MORE flag set) when data is available and is read. Once an error occurs or the socket ends, the multishot will be removed and a completion without IORING_CQE_F_MORE will be posted. The benefit to this is that the recv is much more performant. * Subsequent receives are queued up straight away without requiring the application to finish a processing loop. * If there are more data in the socket (sat the provided buffer size is smaller than the socket buffer) then the data is immediately returned, improving batching. * Poll is only armed once and reused, saving CPU cycles Signed-off-by:
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Dylan Yudaken authored
Similar to multishot poll, drop multishot accept when CQE overflow occurs. Signed-off-by:
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Dylan Yudaken authored
On overflow, multishot poll can still complete with the IORING_CQE_F_MORE flag set. If in the meantime the user clears a CQE and a the poll was cancelled then the poll will post a CQE without the IORING_CQE_F_MORE (and likely result -ECANCELED). However when processing the application will encounter the non-overflow CQE which indicates that there will be no more events posted. Typical userspace applications would free memory associated with the poll in this case. It will then subsequently receive the earlier CQE which has overflowed, which breaks the contract given by the IORING_CQE_F_MORE flag. Signed-off-by:
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Dylan Yudaken authored
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:
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Dylan Yudaken authored
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:
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Dylan Yudaken authored
The values returned are a bit confusing, where 0 and 1 have implied meaning, so add some definitions for them. Signed-off-by:
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Dylan Yudaken authored
Rather than passing an error back to the user with a buffer attached, recycle the buffer immediately. Signed-off-by:
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Dylan Yudaken authored
When using BUFFER_SELECT there is no technical requirement that the user actually provides iov, and this removes one copy_from_user call. So allow iov_len to be 0. Signed-off-by:
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Dylan Yudaken authored
Attempt to restore bgid. This is needed when recycling unused buffers as the next time around it will want the correct bgid. Signed-off-by:
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Dylan Yudaken authored
If user gives 0 for length, we can set it from the available buffer size. Signed-off-by:
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Pavel Begunkov authored
From recently io_uring provides an option to allocate a file index for operation registering fixed files. However, it's utterly unusable with mixed approaches when for a part of files the userspace knows better where to place it, as it may race and users don't have any sane way to pick a slot and hoping it will not be taken. Let the userspace to register a range of fixed file slots in which the auto-allocation happens. The use case is splittting the fixed table in two parts, where on of them is used for auto-allocation and another for slot-specified operations. Signed-off-by:
Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/66ab0394e436f38437cf7c44676e1920d09687ad.1656154403.git.asml.silence@gmail.comSigned-off-by:
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Jens Axboe authored
With IORING_OP_MSG_RING, one ring can send a message to another ring. Extend that support to also allow sending a fixed file descriptor to that ring, enabling one ring to pass a registered descriptor to another one. Arguments are extended to pass in: sqe->addr3 fixed file slot in source ring sqe->file_index fixed file slot in destination ring IORING_OP_MSG_RING is extended to take a command argument in sqe->addr. If set to zero (or IORING_MSG_DATA), it sends just a message like before. If set to IORING_MSG_SEND_FD, a fixed file descriptor is sent according to the above arguments. Two common use cases for this are: 1) Server needs to be shutdown or restarted, pass file descriptors to another onei 2) Backend is split, and one accepts connections, while others then get the fd passed and handle the actual connection. Both of those are classic SCM_RIGHTS use cases, and it's not possible to support them with direct descriptors today. By default, this will post a CQE to the target ring, similarly to how IORING_MSG_DATA does it. If IORING_MSG_RING_CQE_SKIP is set, no message is posted to the target ring. The issuer is expected to notify the receiver side separately. Signed-off-by: -
Jens Axboe authored
Put it with the filetable code, which is where it belongs. While doing so, have the helpers take a ctx rather than an io_kiocb. It doesn't make sense to use a request, as it's not an operation on the request itself. It applies to the ring itself. Signed-off-by: -
Gustavo A. R. Silva authored
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/78Signed-off-by:
Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by:
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Pavel Begunkov authored
io_uring_enter() takes ctx->refs, which was previously preventing racing with register quiesce. However, as register now doesn't touch the refs, we can freely kill extra ctx pinning and rely on the fact that we're holding a file reference preventing the ring from being destroyed. Signed-off-by:
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Pavel Begunkov authored
Registered rings are per definitions io_uring files, so we don't need to additionally verify them. Signed-off-by:
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Pavel Begunkov authored
io_run_task_work() accounts for TIF_NOTIFY_SIGNAL, so no need to have an second check in io_run_task_work_sig(). Signed-off-by:
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Pavel Begunkov authored
Now as both normal and fallback paths use llist, just keep one node head in struct io_task_work and kill off ->fallback_node. Signed-off-by:
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Pavel Begunkov authored
io_fail_links() is called with ->completion_lock held and for that reason we'd want to keep it as small as we can. Instead of doing __io_req_complete_post() for each linked request under the lock, fail them in a task_work handler under ->uring_lock. Signed-off-by:
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Jens Axboe authored
We really don't care about this at all in terms of performance. Outside of having it already be marked unlikely(), shove it into a separate __cold function. Signed-off-by: -
Hao Xu authored
Make io_kbuf_recycle_ring() inline since it is the fast path of provided buffer. Signed-off-by:
Hao Xu <howeyxu@tencent.com> Link: https://lore.kernel.org/r/20220623130126.179232-1-hao.xu@linux.devSigned-off-by:
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Pavel Begunkov authored
The final poll_refs put in __io_arm_poll_handler() takes quite some cycles. When we're arming from the original task context task_work won't be run, so in this case we can assume that we won't race with task_works and so not take the initial ownership ref. One caveat is that after arming a poll we may race with it, so we have to add a bunch of io_poll_get_ownership() hidden inside of io_poll_can_finish_inline() whenever we want to complete arming inline. For the same reason we can't just set REQ_F_DOUBLE_POLL in __io_queue_proc() and so need to sync with the first poll entry by taking its wq head lock. Signed-off-by:
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Pavel Begunkov authored
__io_arm_poll_handler() errors parsing is a horror, in case it failed it returns 0 and the caller is expected to look at ipt.error, which already led us to a number of problems before. When it returns a valid mask, leave it as it's not, i.e. return 1 and store the mask in ipt.result_mask. In case of a failure that can be handled inline return an error code (negative value), and return 0 if __io_arm_poll_handler() took ownership of the request and will complete it. Signed-off-by:
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Pavel Begunkov authored
The rules for __io_arm_poll_handler()'s result parsing are complicated, as the first step don't pass return a mask but pass back a positive return code and fill ipt->result_mask. Signed-off-by:
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Pavel Begunkov authored
Extract a helper function for apoll allocation, makes the code easier to read. Signed-off-by:
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Pavel Begunkov authored
Remove events argument from *io_poll_execute(), it's not needed and not used. Signed-off-by:
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Pavel Begunkov authored
We store a req pointer in wqe->private but also take one bit to mark double poll entries. Replace macro helpers with inline functions for better type checking and also name the double flag. Signed-off-by:
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Jens Axboe authored
The io_uring cancelation API is async, like any other API that we expose there. For the case of finding a request to cancel, or not finding one, it is fully sync in that when submission returns, the CQE for both the cancelation request and the targeted request have been posted to the CQ ring. However, if the targeted work is being executed by io-wq, the API can only start the act of canceling it. This makes it difficult to use in some circumstances, as the caller then has to wait for the CQEs to come in and match on the same cancelation data there. Provide a IORING_REGISTER_SYNC_CANCEL command for io_uring_register() that does sync cancelations, always. For the io-wq case, it'll wait for the cancelation to come in before returning. The only expected returns from this API is: 0 Request found and canceled fine. > 0 Requests found and canceled. Only happens if asked to cancel multiple requests, and if the work wasn't in progress. -ENOENT Request not found. -ETIME A timeout on the operation was requested, but the timeout expired before we could cancel. and we won't get -EALREADY via this API. If the timeout value passed in is -1 (tv_sec and tv_nsec), then that means that no timeout is requested. Otherwise, the timespec passed in is the amount of time the sync cancel will wait for a successful cancelation. Link: https://github.com/axboe/liburing/discussions/608Signed-off-by:
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Jens Axboe authored
In preparation for not having a request to pass in that carries this state, add a separate cancelation flag that allows the caller to ask for a fixed file for cancelation. Signed-off-by: -
Jens Axboe authored
We just use the io_kiocb passed in to find the io_uring_task, and we already pass in the ctx via cd->ctx anyway. Signed-off-by: -
Hao Xu authored
__io_kbuf_recycle() is only called in io_kbuf_recycle(). Kill it and tweak the code so that the legacy pbuf and ring pbuf code become clear Signed-off-by:
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Dylan Yudaken authored
trace task_work_run to help provide stats on how often task work is run and what batch sizes are coming through. Signed-off-by:
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Dylan Yudaken authored
This is useful for investigating if task_work is batching Signed-off-by:
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Dylan Yudaken authored
Batching task work up is an important performance optimisation, as task_work_add is expensive. In order to keep the semantics replace the task_list with a fake node while processing the old list, and then do a cmpxchg at the end to see if there is more work. Signed-off-by:
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Dylan Yudaken authored
Introduce helpers to atomically switch llist. Will later move this into common code Signed-off-by:
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Dylan Yudaken authored
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:
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Dylan Yudaken authored
this is no longer needed as there is only one caller Signed-off-by:
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Dylan Yudaken authored
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:
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Pavel Begunkov authored
We have an identical copy of io_run_task_work() for io-wq called io_flush_signals(), deduplicate them. Signed-off-by:
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