RDS: recv.c

Upon receiving a datagram from the transport, RDS parses the
headers and potentially queues an ACK.
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/recv.c

+/*
+ * 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/sock.h>
+#include <linux/in.h>
+
+#include "rds.h"
+#include "rdma.h"
+
+void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
+		  __be32 saddr)
+{
+	atomic_set(&inc->i_refcount, 1);
+	INIT_LIST_HEAD(&inc->i_item);
+	inc->i_conn = conn;
+	inc->i_saddr = saddr;
+	inc->i_rdma_cookie = 0;
+}
+
+void rds_inc_addref(struct rds_incoming *inc)
+{
+	rdsdebug("addref inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
+	atomic_inc(&inc->i_refcount);
+}
+
+void rds_inc_put(struct rds_incoming *inc)
+{
+	rdsdebug("put inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
+	if (atomic_dec_and_test(&inc->i_refcount)) {
+		BUG_ON(!list_empty(&inc->i_item));
+
+		inc->i_conn->c_trans->inc_free(inc);
+	}
+}
+
+static void rds_recv_rcvbuf_delta(struct rds_sock *rs, struct sock *sk,
+				  struct rds_cong_map *map,
+				  int delta, __be16 port)
+{
+	int now_congested;
+
+	if (delta == 0)
+		return;
+
+	rs->rs_rcv_bytes += delta;
+	now_congested = rs->rs_rcv_bytes > rds_sk_rcvbuf(rs);
+
+	rdsdebug("rs %p (%pI4:%u) recv bytes %d buf %d "
+	  "now_cong %d delta %d\n",
+	  rs, &rs->rs_bound_addr,
+	  ntohs(rs->rs_bound_port), rs->rs_rcv_bytes,
+	  rds_sk_rcvbuf(rs), now_congested, delta);
+
+	/* wasn't -> am congested */
+	if (!rs->rs_congested && now_congested) {
+		rs->rs_congested = 1;
+		rds_cong_set_bit(map, port);
+		rds_cong_queue_updates(map);
+	}
+	/* was -> aren't congested */
+	/* Require more free space before reporting uncongested to prevent
+	   bouncing cong/uncong state too often */
+	else if (rs->rs_congested && (rs->rs_rcv_bytes < (rds_sk_rcvbuf(rs)/2))) {
+		rs->rs_congested = 0;
+		rds_cong_clear_bit(map, port);
+		rds_cong_queue_updates(map);
+	}
+
+	/* do nothing if no change in cong state */
+}
+
+/*
+ * Process all extension headers that come with this message.
+ */
+static void rds_recv_incoming_exthdrs(struct rds_incoming *inc, struct rds_sock *rs)
+{
+	struct rds_header *hdr = &inc->i_hdr;
+	unsigned int pos = 0, type, len;
+	union {
+		struct rds_ext_header_version version;
+		struct rds_ext_header_rdma rdma;
+		struct rds_ext_header_rdma_dest rdma_dest;
+	} buffer;
+
+	while (1) {
+		len = sizeof(buffer);
+		type = rds_message_next_extension(hdr, &pos, &buffer, &len);
+		if (type == RDS_EXTHDR_NONE)
+			break;
+		/* Process extension header here */
+		switch (type) {
+		case RDS_EXTHDR_RDMA:
+			rds_rdma_unuse(rs, be32_to_cpu(buffer.rdma.h_rdma_rkey), 0);
+			break;
+
+		case RDS_EXTHDR_RDMA_DEST:
+			/* We ignore the size for now. We could stash it
+			 * somewhere and use it for error checking. */
+			inc->i_rdma_cookie = rds_rdma_make_cookie(
+					be32_to_cpu(buffer.rdma_dest.h_rdma_rkey),
+					be32_to_cpu(buffer.rdma_dest.h_rdma_offset));
+
+			break;
+		}
+	}
+}
+
+/*
+ * The transport must make sure that this is serialized against other
+ * rx and conn reset on this specific conn.
+ *
+ * We currently assert that only one fragmented message will be sent
+ * down a connection at a time.  This lets us reassemble in the conn
+ * instead of per-flow which means that we don't have to go digging through
+ * flows to tear down partial reassembly progress on conn failure and
+ * we save flow lookup and locking for each frag arrival.  It does mean
+ * that small messages will wait behind large ones.  Fragmenting at all
+ * is only to reduce the memory consumption of pre-posted buffers.
+ *
+ * The caller passes in saddr and daddr instead of us getting it from the
+ * conn.  This lets loopback, who only has one conn for both directions,
+ * tell us which roles the addrs in the conn are playing for this message.
+ */
+void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
+		       struct rds_incoming *inc, gfp_t gfp, enum km_type km)
+{
+	struct rds_sock *rs = NULL;
+	struct sock *sk;
+	unsigned long flags;
+
+	inc->i_conn = conn;
+	inc->i_rx_jiffies = jiffies;
+
+	rdsdebug("conn %p next %llu inc %p seq %llu len %u sport %u dport %u "
+		 "flags 0x%x rx_jiffies %lu\n", conn,
+		 (unsigned long long)conn->c_next_rx_seq,
+		 inc,
+		 (unsigned long long)be64_to_cpu(inc->i_hdr.h_sequence),
+		 be32_to_cpu(inc->i_hdr.h_len),
+		 be16_to_cpu(inc->i_hdr.h_sport),
+		 be16_to_cpu(inc->i_hdr.h_dport),
+		 inc->i_hdr.h_flags,
+		 inc->i_rx_jiffies);
+
+	/*
+	 * Sequence numbers should only increase.  Messages get their
+	 * sequence number as they're queued in a sending conn.  They
+	 * can be dropped, though, if the sending socket is closed before
+	 * they hit the wire.  So sequence numbers can skip forward
+	 * under normal operation.  They can also drop back in the conn
+	 * failover case as previously sent messages are resent down the
+	 * new instance of a conn.  We drop those, otherwise we have
+	 * to assume that the next valid seq does not come after a
+	 * hole in the fragment stream.
+	 *
+	 * The headers don't give us a way to realize if fragments of
+	 * a message have been dropped.  We assume that frags that arrive
+	 * to a flow are part of the current message on the flow that is
+	 * being reassembled.  This means that senders can't drop messages
+	 * from the sending conn until all their frags are sent.
+	 *
+	 * XXX we could spend more on the wire to get more robust failure
+	 * detection, arguably worth it to avoid data corruption.
+	 */
+	if (be64_to_cpu(inc->i_hdr.h_sequence) < conn->c_next_rx_seq
+	 && (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
+		rds_stats_inc(s_recv_drop_old_seq);
+		goto out;
+	}
+	conn->c_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;
+
+	if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
+		rds_stats_inc(s_recv_ping);
+		rds_send_pong(conn, inc->i_hdr.h_sport);
+		goto out;
+	}
+
+	rs = rds_find_bound(daddr, inc->i_hdr.h_dport);
+	if (rs == NULL) {
+		rds_stats_inc(s_recv_drop_no_sock);
+		goto out;
+	}
+
+	/* Process extension headers */
+	rds_recv_incoming_exthdrs(inc, rs);
+
+	/* We can be racing with rds_release() which marks the socket dead. */
+	sk = rds_rs_to_sk(rs);
+
+	/* serialize with rds_release -> sock_orphan */
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		rdsdebug("adding inc %p to rs %p's recv queue\n", inc, rs);
+		rds_stats_inc(s_recv_queued);
+		rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+				      be32_to_cpu(inc->i_hdr.h_len),
+				      inc->i_hdr.h_dport);
+		rds_inc_addref(inc);
+		list_add_tail(&inc->i_item, &rs->rs_recv_queue);
+		__rds_wake_sk_sleep(sk);
+	} else {
+		rds_stats_inc(s_recv_drop_dead_sock);
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+
+out:
+	if (rs)
+		rds_sock_put(rs);
+}
+
+/*
+ * be very careful here.  This is being called as the condition in
+ * wait_event_*() needs to cope with being called many times.
+ */
+static int rds_next_incoming(struct rds_sock *rs, struct rds_incoming **inc)
+{
+	unsigned long flags;
+
+	if (*inc == NULL) {
+		read_lock_irqsave(&rs->rs_recv_lock, flags);
+		if (!list_empty(&rs->rs_recv_queue)) {
+			*inc = list_entry(rs->rs_recv_queue.next,
+					  struct rds_incoming,
+					  i_item);
+			rds_inc_addref(*inc);
+		}
+		read_unlock_irqrestore(&rs->rs_recv_lock, flags);
+	}
+
+	return *inc != NULL;
+}
+
+static int rds_still_queued(struct rds_sock *rs, struct rds_incoming *inc,
+			    int drop)
+{
+	struct sock *sk = rds_rs_to_sk(rs);
+	int ret = 0;
+	unsigned long flags;
+
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	if (!list_empty(&inc->i_item)) {
+		ret = 1;
+		if (drop) {
+			/* XXX make sure this i_conn is reliable */
+			rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+					      -be32_to_cpu(inc->i_hdr.h_len),
+					      inc->i_hdr.h_dport);
+			list_del_init(&inc->i_item);
+			rds_inc_put(inc);
+		}
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+
+	rdsdebug("inc %p rs %p still %d dropped %d\n", inc, rs, ret, drop);
+	return ret;
+}
+
+/*
+ * Pull errors off the error queue.
+ * If msghdr is NULL, we will just purge the error queue.
+ */
+int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msghdr)
+{
+	struct rds_notifier *notifier;
+	struct rds_rdma_notify cmsg;
+	unsigned int count = 0, max_messages = ~0U;
+	unsigned long flags;
+	LIST_HEAD(copy);
+	int err = 0;
+
+
+	/* put_cmsg copies to user space and thus may sleep. We can't do this
+	 * with rs_lock held, so first grab as many notifications as we can stuff
+	 * in the user provided cmsg buffer. We don't try to copy more, to avoid
+	 * losing notifications - except when the buffer is so small that it wouldn't
+	 * even hold a single notification. Then we give him as much of this single
+	 * msg as we can squeeze in, and set MSG_CTRUNC.
+	 */
+	if (msghdr) {
+		max_messages = msghdr->msg_controllen / CMSG_SPACE(sizeof(cmsg));
+		if (!max_messages)
+			max_messages = 1;
+	}
+
+	spin_lock_irqsave(&rs->rs_lock, flags);
+	while (!list_empty(&rs->rs_notify_queue) && count < max_messages) {
+		notifier = list_entry(rs->rs_notify_queue.next,
+				struct rds_notifier, n_list);
+		list_move(&notifier->n_list, &copy);
+		count++;
+	}
+	spin_unlock_irqrestore(&rs->rs_lock, flags);
+
+	if (!count)
+		return 0;
+
+	while (!list_empty(&copy)) {
+		notifier = list_entry(copy.next, struct rds_notifier, n_list);
+
+		if (msghdr) {
+			cmsg.user_token = notifier->n_user_token;
+			cmsg.status  = notifier->n_status;
+
+			err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_RDMA_STATUS,
+					sizeof(cmsg), &cmsg);
+			if (err)
+				break;
+		}
+
+		list_del_init(&notifier->n_list);
+		kfree(notifier);
+	}
+
+	/* If we bailed out because of an error in put_cmsg,
+	 * we may be left with one or more notifications that we
+	 * didn't process. Return them to the head of the list. */
+	if (!list_empty(&copy)) {
+		spin_lock_irqsave(&rs->rs_lock, flags);
+		list_splice(&copy, &rs->rs_notify_queue);
+		spin_unlock_irqrestore(&rs->rs_lock, flags);
+	}
+
+	return err;
+}
+
+/*
+ * Queue a congestion notification
+ */
+static int rds_notify_cong(struct rds_sock *rs, struct msghdr *msghdr)
+{
+	uint64_t notify = rs->rs_cong_notify;
+	unsigned long flags;
+	int err;
+
+	err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_CONG_UPDATE,
+			sizeof(notify), &notify);
+	if (err)
+		return err;
+
+	spin_lock_irqsave(&rs->rs_lock, flags);
+	rs->rs_cong_notify &= ~notify;
+	spin_unlock_irqrestore(&rs->rs_lock, flags);
+
+	return 0;
+}
+
+/*
+ * Receive any control messages.
+ */
+static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg)
+{
+	int ret = 0;
+
+	if (inc->i_rdma_cookie) {
+		ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
+				sizeof(inc->i_rdma_cookie), &inc->i_rdma_cookie);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int rds_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
+		size_t size, int msg_flags)
+{
+	struct sock *sk = sock->sk;
+	struct rds_sock *rs = rds_sk_to_rs(sk);
+	long timeo;
+	int ret = 0, nonblock = msg_flags & MSG_DONTWAIT;
+	struct sockaddr_in *sin;
+	struct rds_incoming *inc = NULL;
+
+	/* udp_recvmsg()->sock_recvtimeo() gets away without locking too.. */
+	timeo = sock_rcvtimeo(sk, nonblock);
+
+	rdsdebug("size %zu flags 0x%x timeo %ld\n", size, msg_flags, timeo);
+
+	if (msg_flags & MSG_OOB)
+		goto out;
+
+	/* If there are pending notifications, do those - and nothing else */
+	if (!list_empty(&rs->rs_notify_queue)) {
+		ret = rds_notify_queue_get(rs, msg);
+		goto out;
+	}
+
+	if (rs->rs_cong_notify) {
+		ret = rds_notify_cong(rs, msg);
+		goto out;
+	}
+
+	while (1) {
+		if (!rds_next_incoming(rs, &inc)) {
+			if (nonblock) {
+				ret = -EAGAIN;
+				break;
+			}
+
+			timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
+						rds_next_incoming(rs, &inc),
+						timeo);
+			rdsdebug("recvmsg woke inc %p timeo %ld\n", inc,
+				 timeo);
+			if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
+				continue;
+
+			ret = timeo;
+			if (ret == 0)
+				ret = -ETIMEDOUT;
+			break;
+		}
+
+		rdsdebug("copying inc %p from %pI4:%u to user\n", inc,
+			 &inc->i_conn->c_faddr,
+			 ntohs(inc->i_hdr.h_sport));
+		ret = inc->i_conn->c_trans->inc_copy_to_user(inc, msg->msg_iov,
+							     size);
+		if (ret < 0)
+			break;
+
+		/*
+		 * if the message we just copied isn't at the head of the
+		 * recv queue then someone else raced us to return it, try
+		 * to get the next message.
+		 */
+		if (!rds_still_queued(rs, inc, !(msg_flags & MSG_PEEK))) {
+			rds_inc_put(inc);
+			inc = NULL;
+			rds_stats_inc(s_recv_deliver_raced);
+			continue;
+		}
+
+		if (ret < be32_to_cpu(inc->i_hdr.h_len)) {
+			if (msg_flags & MSG_TRUNC)
+				ret = be32_to_cpu(inc->i_hdr.h_len);
+			msg->msg_flags |= MSG_TRUNC;
+		}
+
+		if (rds_cmsg_recv(inc, msg)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		rds_stats_inc(s_recv_delivered);
+
+		sin = (struct sockaddr_in *)msg->msg_name;
+		if (sin) {
+			sin->sin_family = AF_INET;
+			sin->sin_port = inc->i_hdr.h_sport;
+			sin->sin_addr.s_addr = inc->i_saddr;
+			memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+		}
+		break;
+	}
+
+	if (inc)
+		rds_inc_put(inc);
+
+out:
+	return ret;
+}
+
+/*
+ * The socket is being shut down and we're asked to drop messages that were
+ * queued for recvmsg.  The caller has unbound the socket so the receive path
+ * won't queue any more incoming fragments or messages on the socket.
+ */
+void rds_clear_recv_queue(struct rds_sock *rs)
+{
+	struct sock *sk = rds_rs_to_sk(rs);
+	struct rds_incoming *inc, *tmp;
+	unsigned long flags;
+
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	list_for_each_entry_safe(inc, tmp, &rs->rs_recv_queue, i_item) {
+		rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+				      -be32_to_cpu(inc->i_hdr.h_len),
+				      inc->i_hdr.h_dport);
+		list_del_init(&inc->i_item);
+		rds_inc_put(inc);
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+}
+
+/*
+ * inc->i_saddr isn't used here because it is only set in the receive
+ * path.
+ */
+void rds_inc_info_copy(struct rds_incoming *inc,
+		       struct rds_info_iterator *iter,
+		       __be32 saddr, __be32 daddr, int flip)
+{
+	struct rds_info_message minfo;
+
+	minfo.seq = be64_to_cpu(inc->i_hdr.h_sequence);
+	minfo.len = be32_to_cpu(inc->i_hdr.h_len);
+
+	if (flip) {
+		minfo.laddr = daddr;
+		minfo.faddr = saddr;
+		minfo.lport = inc->i_hdr.h_dport;
+		minfo.fport = inc->i_hdr.h_sport;
+	} else {
+		minfo.laddr = saddr;
+		minfo.faddr = daddr;
+		minfo.lport = inc->i_hdr.h_sport;
+		minfo.fport = inc->i_hdr.h_dport;
+	}
+
+	rds_info_copy(iter, &minfo, sizeof(minfo));
+}