From a377132154ab8404dafcc52e8bc0c73050a954c2 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 24 Sep 2024 05:57:31 -0600 Subject: io_uring/msg_ring: add support for sending a sync message Normally MSG_RING requires both a source and a destination ring. But some users don't always have a ring avilable to send a message from, yet they still need to notify a target ring. Add support for using io_uring_register(2) without having a source ring, using a file descriptor of -1 for that. Internally those are called blind registration opcodes. Implement IORING_REGISTER_SEND_MSG_RING as a blind opcode, which simply takes an sqe that the application can put on the stack and use the normal liburing helpers to initialize it. Then the app can call: io_uring_register(-1, IORING_REGISTER_SEND_MSG_RING, &sqe, 1); and get the same behavior in terms of the target, where a CQE is posted with the details given in the sqe. For now this takes a single sqe pointer argument, and hence arg must be set to that, and nr_args must be 1. Could easily be extended to take an array of sqes, but for now let's keep it simple. Link: https://lore.kernel.org/r/20240924115932.116167-3-axboe@kernel.dk Signed-off-by: Jens Axboe --- include/uapi/linux/io_uring.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 1fe79e750470..86cb385fe0b5 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -612,6 +612,9 @@ enum io_uring_register_op { /* clone registered buffers from source ring to current ring */ IORING_REGISTER_CLONE_BUFFERS = 30, + /* send MSG_RING without having a ring */ + IORING_REGISTER_SEND_MSG_RING = 31, + /* this goes last */ IORING_REGISTER_LAST, -- cgit v1.2.3