io_uring/net: use async caches for async prep

send/recv have async_data caches but there are only used from within
issue handlers. Extend their use also to ->prep_async, should be handy
with links and IOSQE_ASYNC.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b9a2264b807582a97ed606c5bfcdc2399384e8a5.1662639236.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/net.c

@@ -126,8 +126,8 @@ static void io_netmsg_recycle(struct io_kiocb *req, unsigned int issue_flags)
 	}
 }
 
-static struct io_async_msghdr *io_recvmsg_alloc_async(struct io_kiocb *req,
-						      unsigned int issue_flags)
+static struct io_async_msghdr *io_msg_alloc_async(struct io_kiocb *req,
+						  unsigned int issue_flags)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_cache_entry *entry;
@@ -148,6 +148,12 @@ static struct io_async_msghdr *io_recvmsg_alloc_async(struct io_kiocb *req,
 	return NULL;
 }
 
+static inline struct io_async_msghdr *io_msg_alloc_async_prep(struct io_kiocb *req)
+{
+	/* ->prep_async is always called from the submission context */
+	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)
@@ -156,7 +162,7 @@ static int io_setup_async_msg(struct io_kiocb *req,
 
 	if (req_has_async_data(req))
 		return -EAGAIN;
-	async_msg = io_recvmsg_alloc_async(req, issue_flags);
+	async_msg = io_msg_alloc_async(req, issue_flags);
 	if (!async_msg) {
 		kfree(kmsg->free_iov);
 		return -ENOMEM;
@@ -217,6 +223,8 @@ int io_sendmsg_prep_async(struct io_kiocb *req)
 {
 	int ret;
 
+	if (!io_msg_alloc_async_prep(req))
+		return -ENOMEM;
 	ret = io_sendmsg_copy_hdr(req, req->async_data);
 	if (!ret)
 		req->flags |= REQ_F_NEED_CLEANUP;
@@ -504,6 +512,8 @@ int io_recvmsg_prep_async(struct io_kiocb *req)
 {
 	int ret;
 
+	if (!io_msg_alloc_async_prep(req))
+		return -ENOMEM;
 	ret = io_recvmsg_copy_hdr(req, req->async_data);
 	if (!ret)
 		req->flags |= REQ_F_NEED_CLEANUP;

io_uring/opdef.c

@@ -146,6 +146,7 @@ const struct io_op_def io_op_defs[] = {
 		.unbound_nonreg_file	= 1,
 		.pollout		= 1,
 		.ioprio			= 1,
+		.manual_alloc		= 1,
 		.name			= "SENDMSG",
 #if defined(CONFIG_NET)
 		.async_size		= sizeof(struct io_async_msghdr),
@@ -163,6 +164,7 @@ const struct io_op_def io_op_defs[] = {
 		.pollin			= 1,
 		.buffer_select		= 1,
 		.ioprio			= 1,
+		.manual_alloc		= 1,
 		.name			= "RECVMSG",
 #if defined(CONFIG_NET)
 		.async_size		= sizeof(struct io_async_msghdr),