linux/io_uring/poll.c, branch v6.7

io_uring/poll: don't enable lazy wake for POLLEXCLUSIVE

2023-12-13T15:58:15Z

There are a few quirks around using lazy wake for poll unconditionally, and one of them is related the EPOLLEXCLUSIVE. Those may trigger exclusive wakeups, which wake a limited number of entries in the wait queue. If that wake number is less than the number of entries someone is waiting for (and that someone is also using DEFER_TASKRUN), then we can get stuck waiting for more entries while we should be processing the ones we already got. If we're doing exclusive poll waits, flag the request as not being compatible with lazy wakeups. Reported-by: Pavel Begunkov Fixes: 6ce4a93dbb5b ("io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups") Signed-off-by: Jens Axboe

io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups

2023-10-19T12:42:29Z

With poll triggered retries, each event trigger will cause a task_work item to be added for processing. If the ring is setup with IORING_SETUP_DEFER_TASKRUN and a task is waiting on multiple events to complete, any task_work addition will wake the task for processing these items. This can cause more context switches than we would like, if the application is deliberately waiting on multiple items to increase efficiency. For example, if an application has receive multishot armed for sockets and wants to wait for N to complete within M usec of time, we should not be waking up and processing these items until we have all the events we asked for. By switching the poll trigger to lazy wake, we'll process them when they are all ready, in one swoop, rather than wake multiple times only to process one and then go back to sleep. At some point we probably want to look at just making the lazy wake the default, but for now, let's just selectively enable it where it makes sense. Signed-off-by: Jens Axboe

io_uring: never overflow io_aux_cqe

2023-08-11T16:42:57Z

Now all callers of io_aux_cqe() set allow_overflow to false, remove the parameter and not allow overflowing auxilary multishot cqes. When CQ is full the function callers and all multishot requests in general are expected to complete the request. That prevents indefinite in-background grows of the overflow list and let's the userspace to handle the backlog at its own pace. Resubmitting a request should also be faster than accounting a bunch of overflows, so it should be better for perf when it happens, but a well behaving userspace should be trying to avoid overflows in any case. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/bb20d14d708ea174721e58bb53786b0521e4dd6d.1691757663.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring/cancel: support opcode based lookup and cancelation

2023-07-17T16:05:48Z

Add IORING_ASYNC_CANCEL_OP flag for cancelation, which allows the application to target cancelation based on the opcode of the original request. Signed-off-by: Jens Axboe

io_uring: use cancelation match helper for poll and timeout requests

2023-07-17T16:05:48Z

Get rid of the request vs io_cancel_data checking and just use the exported helper for this. Signed-off-by: Jens Axboe

io_uring/poll: always set 'ctx' in io_cancel_data

2023-07-17T16:05:48Z

This isn't strictly necessary for this callsite, as it uses it's internal lookup for this cancelation purpose. But let's be consistent with how it's used in general and set ctx as well. Signed-off-by: Jens Axboe

Merge tag 'for-6.5/io_uring-2023-06-23' of git://git.kernel.dk/linux

2023-06-26T19:30:26Z

Pull io_uring updates from Jens Axboe: "Nothing major in this release, just a bunch of cleanups and some optimizations around networking mostly. - clean up file request flags handling (Christoph) - clean up request freeing and CQ locking (Pavel) - support for using pre-registering the io_uring fd at setup time (Josh) - Add support for user allocated ring memory, rather than having the kernel allocate it. Mostly for packing rings into a huge page (me) - avoid an unnecessary double retry on receive (me) - maintain ordering for task_work, which also improves performance (me) - misc cleanups/fixes (Pavel, me)" * tag 'for-6.5/io_uring-2023-06-23' of git://git.kernel.dk/linux: (39 commits) io_uring: merge conditional unlock flush helpers io_uring: make io_cq_unlock_post static io_uring: inline __io_cq_unlock io_uring: fix acquire/release annotations io_uring: kill io_cq_unlock() io_uring: remove IOU_F_TWQ_FORCE_NORMAL io_uring: don't batch task put on reqs free io_uring: move io_clean_op() io_uring: inline io_dismantle_req() io_uring: remove io_free_req_tw io_uring: open code io_put_req_find_next io_uring: add helpers to decode the fixed file file_ptr io_uring: use io_file_from_index in io_msg_grab_file io_uring: use io_file_from_index in __io_sync_cancel io_uring: return REQ_F_ flags from io_file_get_flags io_uring: remove io_req_ffs_set io_uring: remove a confusing comment above io_file_get_flags io_uring: remove the mode variable in io_file_get_flags io_uring: remove __io_file_supports_nowait io_uring: wait interruptibly for request completions on exit ...

io_uring/poll: serialize poll linked timer start with poll removal

2023-06-18T02:21:52Z

We selectively grab the ctx->uring_lock for poll update/removal, but we really should grab it from the start to fully synchronize with linked timeouts. Normally this is indeed the case, but if requests are forced async by the application, we don't fully cover removal and timer disarm within the uring_lock. Make this simpler by having consistent locking state for poll removal. Cc: stable@vger.kernel.org # 6.1+ Reported-by: Querijn Voet Signed-off-by: Jens Axboe

io_uring: cleanup io_aux_cqe() API

2023-06-07T20:59:22Z

Everybody is passing in the request, so get rid of the io_ring_ctx and explicit user_data pass-in. Both the ctx and user_data can be deduced from the request at hand. Signed-off-by: Jens Axboe

io_uring: avoid indirect function calls for the hottest task_work

2023-06-02T14:55:37Z

We use task_work for a variety of reasons, but doing completions or triggering rety after poll are by far the hottest two. Use the indirect funtion call wrappers to avoid the indirect function call if CONFIG_RETPOLINE is set. Signed-off-by: Jens Axboe