Commit 56d8e318 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

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: 6d043ee1 ("io_uring: do msg_ring in target task via tw")
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e12d7a46

io_uring/msg_ring.c

+23 −17
Original line number Diff line number Diff line
@@ -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);

}