io_uring/net: always setup an io_async_msghdr

Rather than use an on-stack one and then need to allocate and copy if
async execution is required, always grab one upfront. This should be
very cheap, and potentially even have cache hotness benefits for
back-to-back send/recv requests.

For any recv type of request, this is probably a good choice in general,
as it's expected that no data is available initially. For send this is
not necessarily the case, as space in the socket buffer is expected to
be available. However, getting a cached io_async_msghdr is very cheap,
and as it should be cache hot, probably the difference here is neglible,
if any.

A nice side benefit is that io_setup_async_msg can get killed
completely, which has some nasty iovec manipulation code.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 47 insertions, 70 deletions

diff --git a/io_uring/net.c b/io_uring/net.c
index b4f78ede070b..d095d3e48fcd 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -161,36 +161,6 @@ static inline struct io_async_msghdr *io_msg_alloc_async_prep(struct io_kiocb *r
 	return io_msg_alloc_async(req, 0);
 }
 
-static int io_setup_async_msg(struct io_kiocb *req,
-			      struct io_async_msghdr *kmsg,
-			      unsigned int issue_flags)
-{
-	struct io_async_msghdr *async_msg;
-
-	if (req_has_async_data(req))
-		return -EAGAIN;
-	async_msg = io_msg_alloc_async(req, issue_flags);
-	if (!async_msg) {
-		kfree(kmsg->free_iov);
-		return -ENOMEM;
-	}
-	req->flags |= REQ_F_NEED_CLEANUP;
-	memcpy(async_msg, kmsg, sizeof(*kmsg));
-	if (async_msg->msg.msg_name)
-		async_msg->msg.msg_name = &async_msg->addr;
-
-	if ((req->flags & REQ_F_BUFFER_SELECT) && !async_msg->msg.msg_iter.nr_segs)
-		return -EAGAIN;
-
-	/* if were using fast_iov, set it to the new one */
-	if (iter_is_iovec(&kmsg->msg.msg_iter) && !kmsg->free_iov) {
-		size_t fast_idx = iter_iov(&kmsg->msg.msg_iter) - kmsg->fast_iov;
-		async_msg->msg.msg_iter.__iov = &async_msg->fast_iov[fast_idx];
-	}
-
-	return -EAGAIN;
-}
-
 #ifdef CONFIG_COMPAT
 static int io_compat_msg_copy_hdr(struct io_kiocb *req,
 				  struct io_async_msghdr *iomsg,
@@ -409,7 +379,7 @@ static void io_req_msg_cleanup(struct io_kiocb *req,
 int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	struct socket *sock;
 	unsigned flags;
 	int min_ret = 0;
@@ -423,15 +393,17 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 		kmsg = req->async_data;
 		kmsg->msg.msg_control_user = sr->msg_control;
 	} else {
-		ret = io_sendmsg_copy_hdr(req, &iomsg);
+		kmsg = io_msg_alloc_async(req, issue_flags);
+		if (unlikely(!kmsg))
+			return -ENOMEM;
+		ret = io_sendmsg_copy_hdr(req, kmsg);
 		if (ret)
 			return ret;
-		kmsg = &iomsg;
 	}
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
-		return io_setup_async_msg(req, kmsg, issue_flags);
+		return -EAGAIN;
 
 	flags = sr->msg_flags;
 	if (issue_flags & IO_URING_F_NONBLOCK)
@@ -443,13 +415,13 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (ret < min_ret) {
 		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			kmsg->msg.msg_controllen = 0;
 			kmsg->msg.msg_control = NULL;
 			sr->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -465,7 +437,6 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 }
 
 static struct io_async_msghdr *io_send_setup(struct io_kiocb *req,
-					     struct io_async_msghdr *stack_msg,
 					     unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
@@ -475,8 +446,9 @@ static struct io_async_msghdr *io_send_setup(struct io_kiocb *req,
 	if (req_has_async_data(req)) {
 		kmsg = req->async_data;
 	} else {
-		kmsg = stack_msg;
-		kmsg->free_iov = NULL;
+		kmsg = io_msg_alloc_async(req, issue_flags);
+		if (unlikely(!kmsg))
+			return ERR_PTR(-ENOMEM);
 		kmsg->msg.msg_name = NULL;
 		kmsg->msg.msg_namelen = 0;
 		kmsg->msg.msg_control = NULL;
@@ -500,7 +472,7 @@ static struct io_async_msghdr *io_send_setup(struct io_kiocb *req,
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
-		return ERR_PTR(io_setup_async_msg(req, kmsg, issue_flags));
+		return ERR_PTR(-EAGAIN);
 
 	return kmsg;
 }
@@ -508,7 +480,7 @@ static struct io_async_msghdr *io_send_setup(struct io_kiocb *req,
 int io_send(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	size_t len = sr->len;
 	struct socket *sock;
 	unsigned flags;
@@ -519,7 +491,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(!sock))
 		return -ENOTSOCK;
 
-	kmsg = io_send_setup(req, &iomsg, issue_flags);
+	kmsg = io_send_setup(req, issue_flags);
 	if (IS_ERR(kmsg))
 		return PTR_ERR(kmsg);
 
@@ -538,14 +510,14 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 	ret = sock_sendmsg(sock, &kmsg->msg);
 	if (ret < min_ret) {
 		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -736,9 +708,10 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret,
 			sr->nr_multishot_loops = 0;
 			mshot_retry_ret = IOU_REQUEUE;
 		}
-		*ret = io_setup_async_msg(req, kmsg, issue_flags);
-		if (*ret == -EAGAIN && issue_flags & IO_URING_F_MULTISHOT)
+		if (issue_flags & IO_URING_F_MULTISHOT)
 			*ret = mshot_retry_ret;
+		else
+			*ret = -EAGAIN;
 		return true;
 	}
 
@@ -840,7 +813,7 @@ static int io_recvmsg_multishot(struct socket *sock, struct io_sr_msg *io,
 int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	struct socket *sock;
 	unsigned flags;
 	int ret, min_ret = 0;
@@ -854,15 +827,17 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 	if (req_has_async_data(req)) {
 		kmsg = req->async_data;
 	} else {
-		ret = io_recvmsg_copy_hdr(req, &iomsg);
+		kmsg = io_msg_alloc_async(req, issue_flags);
+		if (unlikely(!kmsg))
+			return -ENOMEM;
+		ret = io_recvmsg_copy_hdr(req, kmsg);
 		if (ret)
 			return ret;
-		kmsg = &iomsg;
 	}
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
-		return io_setup_async_msg(req, kmsg, issue_flags);
+		return -EAGAIN;
 
 	flags = sr->msg_flags;
 	if (force_nonblock)
@@ -904,17 +879,16 @@ retry_multishot:
 
 	if (ret < min_ret) {
 		if (ret == -EAGAIN && force_nonblock) {
-			ret = io_setup_async_msg(req, kmsg, issue_flags);
-			if (ret == -EAGAIN && (issue_flags & IO_URING_F_MULTISHOT)) {
+			if (issue_flags & IO_URING_F_MULTISHOT) {
 				io_kbuf_recycle(req, issue_flags);
 				return IOU_ISSUE_SKIP_COMPLETE;
 			}
-			return ret;
+			return -EAGAIN;
 		}
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -939,7 +913,7 @@ retry_multishot:
 int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	struct socket *sock;
 	unsigned flags;
 	int ret, min_ret = 0;
@@ -949,7 +923,9 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	if (req_has_async_data(req)) {
 		kmsg = req->async_data;
 	} else {
-		kmsg = &iomsg;
+		kmsg = io_msg_alloc_async(req, issue_flags);
+		if (unlikely(!kmsg))
+			return -ENOMEM;
 		kmsg->free_iov = NULL;
 		kmsg->msg.msg_name = NULL;
 		kmsg->msg.msg_namelen = 0;
@@ -969,7 +945,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
-		return io_setup_async_msg(req, kmsg, issue_flags);
+		return -EAGAIN;
 
 	sock = sock_from_file(req->file);
 	if (unlikely(!sock))
@@ -1003,8 +979,7 @@ retry_multishot:
 	ret = sock_recvmsg(sock, &kmsg->msg, flags);
 	if (ret < min_ret) {
 		if (ret == -EAGAIN && force_nonblock) {
-			ret = io_setup_async_msg(req, kmsg, issue_flags);
-			if (ret == -EAGAIN && issue_flags & IO_URING_F_MULTISHOT) {
+			if (issue_flags & IO_URING_F_MULTISHOT) {
 				io_kbuf_recycle(req, issue_flags);
 				return IOU_ISSUE_SKIP_COMPLETE;
 			}
@@ -1016,7 +991,7 @@ retry_multishot:
 			sr->buf += ret;
 			sr->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1212,7 +1187,7 @@ static int io_send_zc_import(struct io_kiocb *req, struct io_async_msghdr *kmsg)
 int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	struct socket *sock;
 	unsigned msg_flags;
 	int ret, min_ret = 0;
@@ -1223,7 +1198,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 	if (!test_bit(SOCK_SUPPORT_ZC, &sock->flags))
 		return -EOPNOTSUPP;
 
-	kmsg = io_send_setup(req, &iomsg, issue_flags);
+	kmsg = io_send_setup(req, issue_flags);
 	if (IS_ERR(kmsg))
 		return PTR_ERR(kmsg);
 
@@ -1246,14 +1221,14 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (unlikely(ret < min_ret)) {
 		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 
 		if (ret > 0 && io_net_retry(sock, kmsg->msg.msg_flags)) {
 			zc->len -= ret;
 			zc->buf += ret;
 			zc->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1281,7 +1256,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr iomsg, *kmsg;
+	struct io_async_msghdr *kmsg;
 	struct socket *sock;
 	unsigned flags;
 	int ret, min_ret = 0;
@@ -1298,15 +1273,17 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 		kmsg = req->async_data;
 		kmsg->msg.msg_control_user = sr->msg_control;
 	} else {
-		ret = io_sendmsg_copy_hdr(req, &iomsg);
+		kmsg = io_msg_alloc_async(req, issue_flags);
+		if (unlikely(!kmsg))
+			return -ENOMEM;
+		ret = io_sendmsg_copy_hdr(req, kmsg);
 		if (ret)
 			return ret;
-		kmsg = &iomsg;
 	}
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
-		return io_setup_async_msg(req, kmsg, issue_flags);
+		return -EAGAIN;
 
 	flags = sr->msg_flags | MSG_ZEROCOPY;
 	if (issue_flags & IO_URING_F_NONBLOCK)
@@ -1320,12 +1297,12 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (unlikely(ret < min_ret)) {
 		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
 			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return io_setup_async_msg(req, kmsg, issue_flags);
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;