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>
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>
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>
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>
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>
We don't need completion_lock for timeout flushing, don't take it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1e3dc657975ac445b80e7bdc40050db783a5935a.1670002973.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
Pull io_uring updates part two from Jens Axboe: - Misc fixes (me, Lin) - Series from Pavel extending the single task exclusive ring mode, yielding nice improvements for the common case of having a single ring per thread (Pavel) - Cleanup for MSG_RING, removing our IOPOLL hack (Pavel) - Further poll cleanups and fixes (Pavel) - Misc cleanups and fixes (Pavel) * tag 'for-6.2/io_uring-next-2022-12-08' of git://git.kernel.dk/linux: (22 commits) io_uring/msg_ring: flag target ring as having task_work, if needed io_uring: skip spinlocking for ->task_complete io_uring: do msg_ring in target task via tw io_uring: extract a io_msg_install_complete helper io_uring: get rid of double locking io_uring: never run tw and fallback in parallel io_uring: use tw for putting rsrc io_uring: force multishot CQEs into task context io_uring: complete all requests in task context io_uring: don't check overflow flush failures io_uring: skip overflow CQE posting for dying ring io_uring: improve io_double_lock_ctx fail handling io_uring: dont remove file from msg_ring reqs io_uring: reshuffle issue_flags io_uring: don't reinstall quiesce node for each tw io_uring: improve rsrc quiesce refs checks io_uring: don't raw spin unlock to match cq_lock io_uring: combine poll tw handlers io_uring: improve poll warning handling io_uring: remove ctx variable in io_poll_check_events ...
Pull io_uring updates from Jens Axboe: - Always ensure proper ordering in case of CQ ring overflow, which then means we can remove some work-arounds for that (Dylan) - Support completion batching for multishot, greatly increasing the efficiency for those (Dylan) - Flag epoll/eventfd wakeups done from io_uring, so that we can easily tell if we're recursing into io_uring again. Previously, this would have resulted in repeated multishot notifications if we had a dependency there. That could happen if an eventfd was registered as the ring eventfd, and we multishot polled for events on it. Or if an io_uring fd was added to epoll, and io_uring had a multishot request for the epoll fd. Test cases here: https://git.kernel.dk/cgit/liburing/commit/?id=919755a7d0096fda08fb6d65ac54ad8d0fe027cd Previously these got terminated when the CQ ring eventually overflowed, now it's handled gracefully (me). - Tightening of the IOPOLL based completions (Pavel) - Optimizations of the networking zero-copy paths (Pavel) - Various tweaks and fixes (Dylan, Pavel) * tag 'for-6.2/io_uring-2022-12-08' of git://git.kernel.dk/linux: (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() ...
->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>