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));

}