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 <hdthky0@xxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> --- io_uring/msg_ring.c | 39 ++++++++++++++++++++++++++++++--------- 1 file changed, 30 insertions(+), 9 deletions(-) diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index 321f5eafef99..a333781565d3 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -65,20 +65,33 @@ static void io_msg_tw_complete(struct callback_head *head) struct io_ring_ctx *target_ctx = req->file->private_data; int ret = 0; - if (current->flags & PF_EXITING) + if (current->flags & PF_EXITING) { ret = -EOWNERDEAD; - else if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) - ret = -EOVERFLOW; + } else { + /* + * If the target ring is using IOPOLL mode, then we need to be + * holding the uring_lock for posting completions. Other ring + * types rely on the regular completion locking, which is + * handled while posting. + */ + if (target_ctx->flags & IORING_SETUP_IOPOLL) + mutex_lock(&target_ctx->uring_lock); + if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) + ret = -EOVERFLOW; + if (target_ctx->flags & IORING_SETUP_IOPOLL) + mutex_unlock(&target_ctx->uring_lock); + } if (ret < 0) req_set_fail(req); io_req_queue_tw_complete(req, ret); } -static int io_msg_ring_data(struct io_kiocb *req) +static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) { struct io_ring_ctx *target_ctx = req->file->private_data; struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); + int ret; if (msg->src_fd || msg->dst_fd || msg->flags) return -EINVAL; @@ -93,10 +106,18 @@ static int io_msg_ring_data(struct io_kiocb *req) return IOU_ISSUE_SKIP_COMPLETE; } - if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) - return 0; - - return -EOVERFLOW; + ret = -EOVERFLOW; + if (target_ctx->flags & IORING_SETUP_IOPOLL) { + if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) + return -EAGAIN; + if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) + ret = 0; + io_double_unlock_ctx(target_ctx); + } else { + if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) + ret = 0; + } + return ret; } static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags) @@ -223,7 +244,7 @@ int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) switch (msg->cmd) { case IORING_MSG_DATA: - ret = io_msg_ring_data(req); + ret = io_msg_ring_data(req, issue_flags); break; case IORING_MSG_SEND_FD: ret = io_msg_send_fd(req, issue_flags); -- 2.39.0
