RDS: Add TCP transport to RDS
This code allows RDS to be tunneled over a TCP connection.
RDMA operations are disabled when using TCP transport,
but this frees RDS from the IB/RDMA stack dependency, and allows
it to be used with standard Ethernet adapters, or in a VM.
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
new file mode 100644
index 0000000..c00daff
--- /dev/null
+++ b/net/rds/tcp_recv.c
@@ -0,0 +1,356 @@
+/*
+ * Copyright (c) 2006 Oracle. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <net/tcp.h>
+
+#include "rds.h"
+#include "tcp.h"
+
+static struct kmem_cache *rds_tcp_incoming_slab;
+
+void rds_tcp_inc_purge(struct rds_incoming *inc)
+{
+ struct rds_tcp_incoming *tinc;
+ tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+ rdsdebug("purging tinc %p inc %p\n", tinc, inc);
+ skb_queue_purge(&tinc->ti_skb_list);
+}
+
+void rds_tcp_inc_free(struct rds_incoming *inc)
+{
+ struct rds_tcp_incoming *tinc;
+ tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+ rds_tcp_inc_purge(inc);
+ rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
+ kmem_cache_free(rds_tcp_incoming_slab, tinc);
+}
+
+/*
+ * this is pretty lame, but, whatever.
+ */
+int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
+ size_t size)
+{
+ struct rds_tcp_incoming *tinc;
+ struct iovec *iov, tmp;
+ struct sk_buff *skb;
+ unsigned long to_copy, skb_off;
+ int ret = 0;
+
+ if (size == 0)
+ goto out;
+
+ tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+ iov = first_iov;
+ tmp = *iov;
+
+ skb_queue_walk(&tinc->ti_skb_list, skb) {
+ skb_off = 0;
+ while (skb_off < skb->len) {
+ while (tmp.iov_len == 0) {
+ iov++;
+ tmp = *iov;
+ }
+
+ to_copy = min(tmp.iov_len, size);
+ to_copy = min(to_copy, skb->len - skb_off);
+
+ rdsdebug("ret %d size %zu skb %p skb_off %lu "
+ "skblen %d iov_base %p iov_len %zu cpy %lu\n",
+ ret, size, skb, skb_off, skb->len,
+ tmp.iov_base, tmp.iov_len, to_copy);
+
+ /* modifies tmp as it copies */
+ if (skb_copy_datagram_iovec(skb, skb_off, &tmp,
+ to_copy)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ size -= to_copy;
+ ret += to_copy;
+ skb_off += to_copy;
+ if (size == 0)
+ goto out;
+ }
+ }
+out:
+ return ret;
+}
+
+/*
+ * We have a series of skbs that have fragmented pieces of the congestion
+ * bitmap. They must add up to the exact size of the congestion bitmap. We
+ * use the skb helpers to copy those into the pages that make up the in-memory
+ * congestion bitmap for the remote address of this connection. We then tell
+ * the congestion core that the bitmap has been changed so that it can wake up
+ * sleepers.
+ *
+ * This is racing with sending paths which are using test_bit to see if the
+ * bitmap indicates that their recipient is congested.
+ */
+
+static void rds_tcp_cong_recv(struct rds_connection *conn,
+ struct rds_tcp_incoming *tinc)
+{
+ struct sk_buff *skb;
+ unsigned int to_copy, skb_off;
+ unsigned int map_off;
+ unsigned int map_page;
+ struct rds_cong_map *map;
+ int ret;
+
+ /* catch completely corrupt packets */
+ if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
+ return;
+
+ map_page = 0;
+ map_off = 0;
+ map = conn->c_fcong;
+
+ skb_queue_walk(&tinc->ti_skb_list, skb) {
+ skb_off = 0;
+ while (skb_off < skb->len) {
+ to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
+ skb->len - skb_off);
+
+ BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
+
+ /* only returns 0 or -error */
+ ret = skb_copy_bits(skb, skb_off,
+ (void *)map->m_page_addrs[map_page] + map_off,
+ to_copy);
+ BUG_ON(ret != 0);
+
+ skb_off += to_copy;
+ map_off += to_copy;
+ if (map_off == PAGE_SIZE) {
+ map_off = 0;
+ map_page++;
+ }
+ }
+ }
+
+ rds_cong_map_updated(map, ~(u64) 0);
+}
+
+struct rds_tcp_desc_arg {
+ struct rds_connection *conn;
+ gfp_t gfp;
+ enum km_type km;
+};
+
+static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
+ unsigned int offset, size_t len)
+{
+ struct rds_tcp_desc_arg *arg = desc->arg.data;
+ struct rds_connection *conn = arg->conn;
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+ struct rds_tcp_incoming *tinc = tc->t_tinc;
+ struct sk_buff *clone;
+ size_t left = len, to_copy;
+
+ rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
+ len);
+
+ /*
+ * tcp_read_sock() interprets partial progress as an indication to stop
+ * processing.
+ */
+ while (left) {
+ if (tinc == NULL) {
+ tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
+ arg->gfp);
+ if (tinc == NULL) {
+ desc->error = -ENOMEM;
+ goto out;
+ }
+ tc->t_tinc = tinc;
+ rdsdebug("alloced tinc %p\n", tinc);
+ rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
+ /*
+ * XXX * we might be able to use the __ variants when
+ * we've already serialized at a higher level.
+ */
+ skb_queue_head_init(&tinc->ti_skb_list);
+ }
+
+ if (left && tc->t_tinc_hdr_rem) {
+ to_copy = min(tc->t_tinc_hdr_rem, left);
+ rdsdebug("copying %zu header from skb %p\n", to_copy,
+ skb);
+ skb_copy_bits(skb, offset,
+ (char *)&tinc->ti_inc.i_hdr +
+ sizeof(struct rds_header) -
+ tc->t_tinc_hdr_rem,
+ to_copy);
+ tc->t_tinc_hdr_rem -= to_copy;
+ left -= to_copy;
+ offset += to_copy;
+
+ if (tc->t_tinc_hdr_rem == 0) {
+ /* could be 0 for a 0 len message */
+ tc->t_tinc_data_rem =
+ be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
+ }
+ }
+
+ if (left && tc->t_tinc_data_rem) {
+ clone = skb_clone(skb, arg->gfp);
+ if (clone == NULL) {
+ desc->error = -ENOMEM;
+ goto out;
+ }
+
+ to_copy = min(tc->t_tinc_data_rem, left);
+ pskb_pull(clone, offset);
+ pskb_trim(clone, to_copy);
+ skb_queue_tail(&tinc->ti_skb_list, clone);
+
+ rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
+ "clone %p data %p len %d\n",
+ skb, skb->data, skb->len, offset, to_copy,
+ clone, clone->data, clone->len);
+
+ tc->t_tinc_data_rem -= to_copy;
+ left -= to_copy;
+ offset += to_copy;
+ }
+
+ if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
+ if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
+ rds_tcp_cong_recv(conn, tinc);
+ else
+ rds_recv_incoming(conn, conn->c_faddr,
+ conn->c_laddr, &tinc->ti_inc,
+ arg->gfp, arg->km);
+
+ tc->t_tinc_hdr_rem = sizeof(struct rds_header);
+ tc->t_tinc_data_rem = 0;
+ tc->t_tinc = NULL;
+ rds_inc_put(&tinc->ti_inc);
+ tinc = NULL;
+ }
+ }
+out:
+ rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
+ len, left, skb->len,
+ skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
+ return len - left;
+}
+
+/* the caller has to hold the sock lock */
+int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp, enum km_type km)
+{
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+ struct socket *sock = tc->t_sock;
+ read_descriptor_t desc;
+ struct rds_tcp_desc_arg arg;
+
+ /* It's like glib in the kernel! */
+ arg.conn = conn;
+ arg.gfp = gfp;
+ arg.km = km;
+ desc.arg.data = &arg;
+ desc.error = 0;
+ desc.count = 1; /* give more than one skb per call */
+
+ tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
+ rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
+ desc.error);
+
+ return desc.error;
+}
+
+/*
+ * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
+ * data_ready.
+ *
+ * if we fail to allocate we're in trouble.. blindly wait some time before
+ * trying again to see if the VM can free up something for us.
+ */
+int rds_tcp_recv(struct rds_connection *conn)
+{
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+ struct socket *sock = tc->t_sock;
+ int ret = 0;
+
+ rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
+
+ lock_sock(sock->sk);
+ ret = rds_tcp_read_sock(conn, GFP_KERNEL, KM_USER0);
+ release_sock(sock->sk);
+
+ return ret;
+}
+
+void rds_tcp_data_ready(struct sock *sk, int bytes)
+{
+ void (*ready)(struct sock *sk, int bytes);
+ struct rds_connection *conn;
+ struct rds_tcp_connection *tc;
+
+ rdsdebug("data ready sk %p bytes %d\n", sk, bytes);
+
+ read_lock(&sk->sk_callback_lock);
+ conn = sk->sk_user_data;
+ if (conn == NULL) { /* check for teardown race */
+ ready = sk->sk_data_ready;
+ goto out;
+ }
+
+ tc = conn->c_transport_data;
+ ready = tc->t_orig_data_ready;
+ rds_tcp_stats_inc(s_tcp_data_ready_calls);
+
+ if (rds_tcp_read_sock(conn, GFP_ATOMIC, KM_SOFTIRQ0) == -ENOMEM)
+ queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+out:
+ read_unlock(&sk->sk_callback_lock);
+ ready(sk, bytes);
+}
+
+int __init rds_tcp_recv_init(void)
+{
+ rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
+ sizeof(struct rds_tcp_incoming),
+ 0, 0, NULL);
+ if (rds_tcp_incoming_slab == NULL)
+ return -ENOMEM;
+ return 0;
+}
+
+void rds_tcp_recv_exit(void)
+{
+ kmem_cache_destroy(rds_tcp_incoming_slab);
+}
