user/sven/linux.git/io_uring/msg_ring.c, branch v6.2-rc8

io_uring/msg_ring: fix remote queue to disabled ring

2023-01-20T16:49:34Z

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 Signed-off-by: Jens Axboe

io_uring/msg_ring: fix flagging remote execution

2023-01-20T16:49:29Z

There is a couple of problems with queueing a tw in io_msg_ring_data() for remote execution. First, once we queue it the target ring can go away and so setting IORING_SQ_TASKRUN there is not safe. Secondly, the userspace might not expect IORING_SQ_TASKRUN. Extract a helper and uniformly use TWA_SIGNAL without TWA_SIGNAL_NO_IPI tricks for now, just as it was done in the original patch. Cc: stable@vger.kernel.org Fixes: 6d043ee1164ca ("io_uring: do msg_ring in target task via tw") Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring/msg_ring: fix missing lock on overflow for IOPOLL

2023-01-19T17:43:59Z

If the target ring is configured with IOPOLL, then we always need to hold the target ring uring_lock before posting CQEs. We could just grab it unconditionally, but since we don't expect many target rings to be of this type, make grabbing the uring_lock conditional on the ring type. Link: https://lore.kernel.org/io-uring/Y8krlYa52%2F0YGqkg@ip-172-31-85-199.ec2.internal/ Reported-by: Xingyuan Mo Signed-off-by: Jens Axboe

io_uring/msg_ring: move double lock/unlock helpers higher up

2023-01-19T16:01:27Z

In preparation for needing them somewhere else, move them and get rid of the unused 'issue_flags' for the unlock side. No functional changes in this patch. Signed-off-by: Jens Axboe

io_uring/msg_ring: flag target ring as having task_work, if needed

2022-12-08T16:36:02Z

Before the recent change, we didn't even wake the targeted task when posting the cqe remotely. Now we do wake it, but we do want to ensure that the recipient knows there's potential work there that needs to get processed to get the CQE posted. OR in IORING_SQ_TASKRUN for that purpose. Link: https://lore.kernel.org/io-uring/2843c6b4-ba9a-b67d-e0f4-957f42098489@kernel.dk/ Fixes: 6d043ee1164c ("io_uring: do msg_ring in target task via tw") Signed-off-by: Jens Axboe

io_uring: do msg_ring in target task via tw

2022-12-07T15:50:57Z

While executing in a context of one io_uring instance msg_ring manipulates another ring. We're trying to keep CQEs posting contained in the context of the ring-owner task, use task_work to send the request to the target ring's task when we're modifying its CQ or trying to install a file. Note, we can't safely use io_uring task_work infra and have to use task_work directly. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/4d76c7b28ed5d71b520de4482fbb7f660f21cd80.1670384893.git.asml.silence@gmail.com [axboe: use TWA_SIGNAL_NO_IPI] Signed-off-by: Jens Axboe

io_uring: extract a io_msg_install_complete helper

2022-12-07T13:47:13Z

Extract a helper called io_msg_install_complete() from io_msg_send_fd(), will be used later. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/1500ca1054cc4286a3ee1c60aacead57fcdfa02a.1670384893.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: get rid of double locking

2022-12-07T13:47:13Z

We don't need to take both uring_locks at once, msg_ring can be split in two parts, first getting a file from the filetable of the first ring and then installing it into the second one. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/a80ecc2bc99c3b3f2cf20015d618b7c51419a797.1670384893.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: improve io_double_lock_ctx fail handling

2022-12-07T13:47:13Z

msg_ring will fail the request if it can't lock rings, instead punt it to io-wq as was originally intended. Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/4697f05afcc37df5c8f89e2fe6d9c7c19f0241f9.1670384893.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: dont remove file from msg_ring reqs

2022-12-07T13:47:13Z

We should not be messing with req->file outside of core paths. Clearing it makes msg_ring non reentrant, i.e. luckily io_msg_send_fd() fails the request on failed io_double_lock_ctx() but clearly was originally intended to do retries instead. Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/e5ac9edadb574fe33f6d727cb8f14ce68262a684.1670384893.git.asml.silence@gmail.com Signed-off-by: Jens Axboe