[PATCH 05/17] io_uring/net: get rid of ->prep_async() for receive side

[Jens Axboe <axboe@kernel.dk>]

Move the io_async_msghdr out of the issue path and into prep handling,
since it's now done unconditionally and hence does not need to be part
of the issue path. This reduces the footprint of the multishot fast
path of multiple invocations of ->issue() per prep, and also means that
we can drop using ->prep_async() for recvmsg as we now do this setup on
the prep side.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/net.c   | 71 +++++++++++++++++++-----------------------------
 io_uring/net.h   |  1 -
 io_uring/opdef.c |  2 --
 3 files changed, 28 insertions(+), 46 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 14491fab6d59..e438b1ac2420 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -596,17 +596,36 @@ static int io_recvmsg_copy_hdr(struct io_kiocb *req,
 					msg.msg_controllen);
 }
 
-int io_recvmsg_prep_async(struct io_kiocb *req)
+static int io_recvmsg_prep_setup(struct io_kiocb *req)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct io_async_msghdr *iomsg;
+	struct io_async_msghdr *kmsg;
 	int ret;
 
-	sr->done_io = 0;
-	if (!io_msg_alloc_async_prep(req))
+	/* always locked for prep */
+	kmsg = io_msg_alloc_async(req, 0);
+	if (unlikely(!kmsg))
 		return -ENOMEM;
-	iomsg = req->async_data;
-	ret = io_recvmsg_copy_hdr(req, iomsg);
+
+	if (req->opcode == IORING_OP_RECV) {
+		kmsg->msg.msg_name = NULL;
+		kmsg->msg.msg_namelen = 0;
+		kmsg->msg.msg_control = NULL;
+		kmsg->msg.msg_get_inq = 1;
+		kmsg->msg.msg_controllen = 0;
+		kmsg->msg.msg_iocb = NULL;
+		kmsg->msg.msg_ubuf = NULL;
+
+		if (!io_do_buffer_select(req)) {
+			ret = import_ubuf(ITER_DEST, sr->buf, sr->len,
+					  &kmsg->msg.msg_iter);
+			if (unlikely(ret))
+				return ret;
+		}
+		return 0;
+	}
+
+	ret = io_recvmsg_copy_hdr(req, kmsg);
 	if (!ret)
 		req->flags |= REQ_F_NEED_CLEANUP;
 	return ret;
@@ -657,7 +676,7 @@ int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		sr->msg_flags |= MSG_CMSG_COMPAT;
 #endif
 	sr->nr_multishot_loops = 0;
-	return 0;
+	return io_recvmsg_prep_setup(req);
 }
 
 static inline void io_recv_prep_retry(struct io_kiocb *req,
@@ -815,7 +834,7 @@ 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 *kmsg;
+	struct io_async_msghdr *kmsg = req->async_data;
 	struct socket *sock;
 	unsigned flags;
 	int ret, min_ret = 0;
@@ -826,17 +845,6 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(!sock))
 		return -ENOTSOCK;
 
-	if (req_has_async_data(req)) {
-		kmsg = req->async_data;
-	} else {
-		kmsg = io_msg_alloc_async(req, issue_flags);
-		if (unlikely(!kmsg))
-			return -ENOMEM;
-		ret = io_recvmsg_copy_hdr(req, kmsg);
-		if (ret)
-			return ret;
-	}
-
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
 		return -EAGAIN;
@@ -915,36 +923,13 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 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 *kmsg;
+	struct io_async_msghdr *kmsg = req->async_data;
 	struct socket *sock;
 	unsigned flags;
 	int ret, min_ret = 0;
 	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	size_t len = sr->len;
 
-	if (req_has_async_data(req)) {
-		kmsg = req->async_data;
-	} else {
-		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;
-		kmsg->msg.msg_control = NULL;
-		kmsg->msg.msg_get_inq = 1;
-		kmsg->msg.msg_controllen = 0;
-		kmsg->msg.msg_iocb = NULL;
-		kmsg->msg.msg_ubuf = NULL;
-
-		if (!io_do_buffer_select(req)) {
-			ret = import_ubuf(ITER_DEST, sr->buf, sr->len,
-					  &kmsg->msg.msg_iter);
-			if (unlikely(ret))
-				return ret;
-		}
-	}
-
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
 		return -EAGAIN;
diff --git a/io_uring/net.h b/io_uring/net.h
index 5c1230f1aaf9..4b4fd9b1b7b4 100644
--- a/io_uring/net.h
+++ b/io_uring/net.h
@@ -42,7 +42,6 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags);
 int io_send(struct io_kiocb *req, unsigned int issue_flags);
 int io_sendrecv_prep_async(struct io_kiocb *req);
 
-int io_recvmsg_prep_async(struct io_kiocb *req);
 int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags);
 int io_recv(struct io_kiocb *req, unsigned int issue_flags);
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 77131826d603..1368193edc57 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -536,7 +536,6 @@ const struct io_cold_def io_cold_defs[] = {
 		.name			= "RECVMSG",
 #if defined(CONFIG_NET)
 		.async_size		= sizeof(struct io_async_msghdr),
-		.prep_async		= io_recvmsg_prep_async,
 		.cleanup		= io_sendmsg_recvmsg_cleanup,
 		.fail			= io_sendrecv_fail,
 #endif
@@ -613,7 +612,6 @@ const struct io_cold_def io_cold_defs[] = {
 		.async_size		= sizeof(struct io_async_msghdr),
 		.cleanup		= io_sendmsg_recvmsg_cleanup,
 		.fail			= io_sendrecv_fail,
-		.prep_async		= io_sendrecv_prep_async,
 #endif
 	},
 	[IORING_OP_OPENAT2] = {
-- 
2.43.0