The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
Possible dependencies:
56d8e3180c06 ("io_uring/msg_ring: fix flagging remote execution") 423d5081d045 ("io_uring/msg_ring: move double lock/unlock helpers higher up") 761c61c15903 ("io_uring/msg_ring: flag target ring as having task_work, if needed") 6d043ee1164c ("io_uring: do msg_ring in target task via tw") 172113101641 ("io_uring: extract a io_msg_install_complete helper") 11373026f296 ("io_uring: get rid of double locking") 4c979eaefa43 ("io_uring: improve io_double_lock_ctx fail handling") b529c96a896b ("io_uring: remove overflow param from io_post_aux_cqe") a77ab745f28d ("io_uring: make io_fill_cqe_aux static") 9b8c54755a2b ("io_uring: add io_aux_cqe which allows deferred completion") 931147ddfa6e ("io_uring: allow defer completion for aux posted cqes") 1bec951c3809 ("io_uring: iopoll protect complete_post") fa18fa2272c7 ("io_uring: inline __io_req_complete_put()") f9d567c75ec2 ("io_uring: inline __io_req_complete_post()") e2ad599d1ed3 ("io_uring: allow multishot recv CQEs to overflow") 515e26961295 ("io_uring: revert "io_uring fix multishot accept ordering"")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 56d8e3180c065c9b78ed77afcd0cf99677a4e22f Mon Sep 17 00:00:00 2001 From: Pavel Begunkov asml.silence@gmail.com Date: Fri, 20 Jan 2023 16:38:05 +0000 Subject: [PATCH] io_uring/msg_ring: fix flagging remote execution
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 asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index a333781565d3..bb868447dcdf 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -58,6 +58,25 @@ void io_msg_ring_cleanup(struct io_kiocb *req) msg->src_file = NULL; }
+static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx) +{ + if (!target_ctx->task_complete) + return false; + return current != target_ctx->submitter_task; +} + +static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func) +{ + struct io_ring_ctx *ctx = req->file->private_data; + struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); + + init_task_work(&msg->tw, func); + if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL)) + return -EOWNERDEAD; + + return IOU_ISSUE_SKIP_COMPLETE; +} + static void io_msg_tw_complete(struct callback_head *head) { struct io_msg *msg = container_of(head, struct io_msg, tw); @@ -96,15 +115,8 @@ static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) if (msg->src_fd || msg->dst_fd || msg->flags) return -EINVAL;
- if (target_ctx->task_complete && current != target_ctx->submitter_task) { - init_task_work(&msg->tw, io_msg_tw_complete); - if (task_work_add(target_ctx->submitter_task, &msg->tw, - TWA_SIGNAL_NO_IPI)) - return -EOWNERDEAD; - - atomic_or(IORING_SQ_TASKRUN, &target_ctx->rings->sq_flags); - return IOU_ISSUE_SKIP_COMPLETE; - } + if (io_msg_need_remote(target_ctx)) + return io_msg_exec_remote(req, io_msg_tw_complete);
ret = -EOVERFLOW; if (target_ctx->flags & IORING_SETUP_IOPOLL) { @@ -202,14 +214,8 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags) req->flags |= REQ_F_NEED_CLEANUP; }
- if (target_ctx->task_complete && current != target_ctx->submitter_task) { - init_task_work(&msg->tw, io_msg_tw_fd_complete); - if (task_work_add(target_ctx->submitter_task, &msg->tw, - TWA_SIGNAL)) - return -EOWNERDEAD; - - return IOU_ISSUE_SKIP_COMPLETE; - } + if (io_msg_need_remote(target_ctx)) + return io_msg_exec_remote(req, io_msg_tw_fd_complete); return io_msg_install_complete(req, issue_flags); }