rxrpc: Define rxrpc_txbuf struct to carry data to be transmitted

Define a struct, rxrpc_txbuf, to carry data to be transmitted instead of a
socket buffer so that it can be placed onto multiple queues at once.  This
also allows the data buffer to be in the same allocation as the internal
data.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 100 insertions, 0 deletions

diff --git a/net/rxrpc/txbuf.c b/net/rxrpc/txbuf.c
new file mode 100644
index 000000000000..66d922ad65d0
--- /dev/null
+++ b/net/rxrpc/txbuf.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* RxRPC Tx data buffering.
+ *
+ * Copyright (C) 2022 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include "ar-internal.h"
+
+static atomic_t rxrpc_txbuf_debug_ids;
+atomic_t rxrpc_nr_txbuf;
+
+/*
+ * Allocate and partially initialise an I/O request structure.
+ */
+struct rxrpc_txbuf *rxrpc_alloc_txbuf(struct rxrpc_call *call, u8 packet_type,
+				      gfp_t gfp)
+{
+	struct rxrpc_txbuf *txb;
+
+	txb = kmalloc(sizeof(*txb), gfp);
+	if (txb) {
+		INIT_LIST_HEAD(&txb->call_link);
+		INIT_LIST_HEAD(&txb->tx_link);
+		refcount_set(&txb->ref, 1);
+		txb->call		= call;
+		txb->call_debug_id	= call->debug_id;
+		txb->debug_id		= atomic_inc_return(&rxrpc_txbuf_debug_ids);
+		txb->space		= sizeof(txb->data);
+		txb->len		= 0;
+		txb->offset		= 0;
+		txb->flags		= 0;
+		txb->seq		= call->tx_top + 1;
+		txb->wire.epoch		= htonl(call->conn->proto.epoch);
+		txb->wire.cid		= htonl(call->cid);
+		txb->wire.callNumber	= htonl(call->call_id);
+		txb->wire.seq		= htonl(txb->seq);
+		txb->wire.type		= packet_type;
+		txb->wire.flags		= call->conn->out_clientflag;
+		txb->wire.userStatus	= 0;
+		txb->wire.securityIndex	= call->security_ix;
+		txb->wire._rsvd		= 0;
+		txb->wire.serviceId	= htons(call->service_id);
+
+		trace_rxrpc_txbuf(txb->debug_id,
+				  txb->call_debug_id, txb->seq, 1,
+				  packet_type == RXRPC_PACKET_TYPE_DATA ?
+				  rxrpc_txbuf_alloc_data :
+				  rxrpc_txbuf_alloc_ack);
+		atomic_inc(&rxrpc_nr_txbuf);
+	}
+
+	return txb;
+}
+
+void rxrpc_get_txbuf(struct rxrpc_txbuf *txb, enum rxrpc_txbuf_trace what)
+{
+	int r;
+
+	__refcount_inc(&txb->ref, &r);
+	trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, r + 1, what);
+}
+
+void rxrpc_see_txbuf(struct rxrpc_txbuf *txb, enum rxrpc_txbuf_trace what)
+{
+	int r = refcount_read(&txb->ref);
+
+	trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, r, what);
+}
+
+static void rxrpc_free_txbuf(struct rcu_head *rcu)
+{
+	struct rxrpc_txbuf *txb = container_of(rcu, struct rxrpc_txbuf, rcu);
+
+	trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, 0,
+			  rxrpc_txbuf_free);
+	kfree(txb);
+	atomic_dec(&rxrpc_nr_txbuf);
+}
+
+void rxrpc_put_txbuf(struct rxrpc_txbuf *txb, enum rxrpc_txbuf_trace what)
+{
+	unsigned int debug_id, call_debug_id;
+	rxrpc_seq_t seq;
+	bool dead;
+	int r;
+
+	if (txb) {
+		debug_id = txb->debug_id;
+		call_debug_id = txb->call_debug_id;
+		seq = txb->seq;
+		dead = __refcount_dec_and_test(&txb->ref, &r);
+		trace_rxrpc_txbuf(debug_id, call_debug_id, seq, r - 1, what);
+		if (dead)
+			call_rcu(&txb->rcu, rxrpc_free_txbuf);
+	}
+}