Merge branch 'mptcp-optimizations'

Mat Martineau says:

====================
mptcp: A few optimizations

Here is a set of patches that we've accumulated and tested in the MPTCP
tree.

Patch 1 removes the MPTCP-level tx skb cache that added complexity but
did not provide a meaningful benefit.

Patch 2 uses the fast socket lock in more places.

Patch 3 improves handling of a data-ready flag.

Patch 4 deletes an unnecessary and racy connection state check.

Patch 5 adds a MIB counter for one type of invalid MPTCP header.

Patch 6 improves self test failure output.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/mib.c

@@ -25,6 +25,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("MPJoinAckHMacFailure", MPTCP_MIB_JOINACKMAC),
 	SNMP_MIB_ITEM("DSSNotMatching", MPTCP_MIB_DSSNOMATCH),
 	SNMP_MIB_ITEM("InfiniteMapRx", MPTCP_MIB_INFINITEMAPRX),
+	SNMP_MIB_ITEM("DSSNoMatchTCP", MPTCP_MIB_DSSTCPMISMATCH),
 	SNMP_MIB_ITEM("DataCsumErr", MPTCP_MIB_DATACSUMERR),
 	SNMP_MIB_ITEM("OFOQueueTail", MPTCP_MIB_OFOQUEUETAIL),
 	SNMP_MIB_ITEM("OFOQueue", MPTCP_MIB_OFOQUEUE),

net/mptcp/mib.h

@@ -18,6 +18,7 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_JOINACKMAC,		/* HMAC was wrong on ACK + MP_JOIN */
 	MPTCP_MIB_DSSNOMATCH,		/* Received a new mapping that did not match the previous one */
 	MPTCP_MIB_INFINITEMAPRX,	/* Received an infinite mapping */
+	MPTCP_MIB_DSSTCPMISMATCH,	/* DSS-mapping did not map with TCP's sequence numbers */
 	MPTCP_MIB_DATACSUMERR,		/* The data checksum fail */
 	MPTCP_MIB_OFOQUEUETAIL,	/* Segments inserted into OoO queue tail */
 	MPTCP_MIB_OFOQUEUE,		/* Segments inserted into OoO queue */

net/mptcp/pm_netlink.c

@@ -540,6 +540,7 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
 	subflow = list_first_entry_or_null(&msk->conn_list, typeof(*subflow), node);
 	if (subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
 		spin_unlock_bh(&msk->pm.lock);
 		pr_debug("send ack for %s%s%s",
@@ -547,9 +548,9 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
 			 mptcp_pm_should_add_signal_ipv6(msk) ? " [ipv6]" : "",
 			 mptcp_pm_should_add_signal_port(msk) ? " [port]" : "");
 
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 		spin_lock_bh(&msk->pm.lock);
 	}
 }
@@ -566,6 +567,7 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 		struct sock *sk = (struct sock *)msk;
 		struct mptcp_addr_info local;
+		bool slow;
 
 		local_address((struct sock_common *)ssk, &local);
 		if (!addresses_equal(&local, addr, addr->port))
@@ -578,9 +580,9 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 
 		spin_unlock_bh(&msk->pm.lock);
 		pr_debug("send ack for mp_prio");
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 		spin_lock_bh(&msk->pm.lock);
 
 		return 0;

net/mptcp/protocol.c

@@ -433,23 +433,25 @@ static void mptcp_send_ack(struct mptcp_sock *msk)
 
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		if (tcp_can_send_ack(ssk))
 			tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 	}
 }
 
 static bool mptcp_subflow_cleanup_rbuf(struct sock *ssk)
 {
+	bool slow;
 	int ret;
 
-	lock_sock(ssk);
+	slow = lock_sock_fast(ssk);
 	ret = tcp_can_send_ack(ssk);
 	if (ret)
 		tcp_cleanup_rbuf(ssk, 1);
-	release_sock(ssk);
+	unlock_sock_fast(ssk, slow);
 	return ret;
 }
 
@@ -684,9 +686,6 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
 	struct sock *sk = (struct sock *)msk;
 	unsigned int moved = 0;
 
-	if (inet_sk_state_load(sk) == TCP_CLOSE)
-		return false;
-
 	__mptcp_move_skbs_from_subflow(msk, ssk, &moved);
 	__mptcp_ofo_queue(msk);
 	if (unlikely(ssk->sk_err)) {
@@ -902,22 +901,14 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
 		df->data_seq + df->data_len == msk->write_seq;
 }
 
-static int mptcp_wmem_with_overhead(struct sock *sk, int size)
+static int mptcp_wmem_with_overhead(int size)
 {
-	struct mptcp_sock *msk = mptcp_sk(sk);
-	int ret, skbs;
-
-	ret = size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT);
-	skbs = (msk->tx_pending_data + size) / msk->size_goal_cache;
-	if (skbs < msk->skb_tx_cache.qlen)
-		return ret;
-
-	return ret + (skbs - msk->skb_tx_cache.qlen) * SKB_TRUESIZE(MAX_TCP_HEADER);
+	return size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT);
 }
 
 static void __mptcp_wmem_reserve(struct sock *sk, int size)
 {
-	int amount = mptcp_wmem_with_overhead(sk, size);
+	int amount = mptcp_wmem_with_overhead(size);
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
 	WARN_ON_ONCE(msk->wmem_reserved);
@@ -1212,49 +1203,8 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
 	return NULL;
 }
 
-static bool mptcp_tx_cache_refill(struct sock *sk, int size,
-				  struct sk_buff_head *skbs, int *total_ts)
-{
-	struct mptcp_sock *msk = mptcp_sk(sk);
-	struct sk_buff *skb;
-	int space_needed;
-
-	if (unlikely(tcp_under_memory_pressure(sk))) {
-		mptcp_mem_reclaim_partial(sk);
-
-		/* under pressure pre-allocate at most a single skb */
-		if (msk->skb_tx_cache.qlen)
-			return true;
-		space_needed = msk->size_goal_cache;
-	} else {
-		space_needed = msk->tx_pending_data + size -
-			       msk->skb_tx_cache.qlen * msk->size_goal_cache;
-	}
-
-	while (space_needed > 0) {
-		skb = __mptcp_do_alloc_tx_skb(sk, sk->sk_allocation);
-		if (unlikely(!skb)) {
-			/* under memory pressure, try to pass the caller a
-			 * single skb to allow forward progress
-			 */
-			while (skbs->qlen > 1) {
-				skb = __skb_dequeue_tail(skbs);
-				*total_ts -= skb->truesize;
-				__kfree_skb(skb);
-			}
-			return skbs->qlen > 0;
-		}
-
-		*total_ts += skb->truesize;
-		__skb_queue_tail(skbs, skb);
-		space_needed -= msk->size_goal_cache;
-	}
-	return true;
-}
-
 static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
 {
-	struct mptcp_sock *msk = mptcp_sk(sk);
 	struct sk_buff *skb;
 
 	if (ssk->sk_tx_skb_cache) {
@@ -1265,22 +1215,6 @@ static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
 		return true;
 	}
 
-	skb = skb_peek(&msk->skb_tx_cache);
-	if (skb) {
-		if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
-			skb = __skb_dequeue(&msk->skb_tx_cache);
-			if (WARN_ON_ONCE(!skb))
-				return false;
-
-			mptcp_wmem_uncharge(sk, skb->truesize);
-			ssk->sk_tx_skb_cache = skb;
-			return true;
-		}
-
-		/* over memory limit, no point to try to allocate a new skb */
-		return false;
-	}
-
 	skb = __mptcp_do_alloc_tx_skb(sk, gfp);
 	if (!skb)
 		return false;
@@ -1296,7 +1230,6 @@ static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
 static bool mptcp_must_reclaim_memory(struct sock *sk, struct sock *ssk)
 {
 	return !ssk->sk_tx_skb_cache &&
-	       !skb_peek(&mptcp_sk(sk)->skb_tx_cache) &&
 	       tcp_under_memory_pressure(sk);
 }
 
@@ -1339,7 +1272,6 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 	/* compute send limit */
 	info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
 	avail_size = info->size_goal;
-	msk->size_goal_cache = info->size_goal;
 	skb = tcp_write_queue_tail(ssk);
 	if (skb) {
 		/* Limit the write to the size available in the
@@ -1688,7 +1620,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	while (msg_data_left(msg)) {
 		int total_ts, frag_truesize = 0;
 		struct mptcp_data_frag *dfrag;
-		struct sk_buff_head skbs;
 		bool dfrag_collapsed;
 		size_t psize, offset;
 
@@ -1721,16 +1652,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		psize = pfrag->size - offset;
 		psize = min_t(size_t, psize, msg_data_left(msg));
 		total_ts = psize + frag_truesize;
-		__skb_queue_head_init(&skbs);
-		if (!mptcp_tx_cache_refill(sk, psize, &skbs, &total_ts))
-			goto wait_for_memory;
 
-		if (!mptcp_wmem_alloc(sk, total_ts)) {
-			__skb_queue_purge(&skbs);
+		if (!mptcp_wmem_alloc(sk, total_ts))
 			goto wait_for_memory;
-		}
 
-		skb_queue_splice_tail(&skbs, &msk->skb_tx_cache);
 		if (copy_page_from_iter(dfrag->page, offset, psize,
 					&msg->msg_iter) != psize) {
 			mptcp_wmem_uncharge(sk, psize + frag_truesize);
@@ -1787,7 +1712,7 @@ static void mptcp_wait_data(struct sock *sk, long *timeo)
 	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 
 	sk_wait_event(sk, timeo,
-		      test_and_clear_bit(MPTCP_DATA_READY, &msk->flags), &wait);
+		      test_bit(MPTCP_DATA_READY, &msk->flags), &wait);
 
 	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 	remove_wait_queue(sk_sleep(sk), &wait);
@@ -2111,10 +2036,8 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		 */
 		if (unlikely(__mptcp_move_skbs(msk)))
 			set_bit(MPTCP_DATA_READY, &msk->flags);
-	} else if (unlikely(!test_bit(MPTCP_DATA_READY, &msk->flags))) {
-		/* data to read but mptcp_wait_data() cleared DATA_READY */
-		set_bit(MPTCP_DATA_READY, &msk->flags);
 	}
+
 out_err:
 	if (cmsg_flags && copied >= 0) {
 		if (cmsg_flags & MPTCP_CMSG_TS)
@@ -2326,13 +2249,14 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 
 	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
-		lock_sock(tcp_sk);
+		slow = lock_sock_fast(tcp_sk);
 		if (tcp_sk->sk_state != TCP_CLOSE) {
 			tcp_send_active_reset(tcp_sk, GFP_ATOMIC);
 			tcp_set_state(tcp_sk, TCP_CLOSE);
 		}
-		release_sock(tcp_sk);
+		unlock_sock_fast(tcp_sk, slow);
 	}
 
 	inet_sk_state_store(sk, TCP_CLOSE);
@@ -2462,13 +2386,11 @@ static int __mptcp_init_sock(struct sock *sk)
 	INIT_LIST_HEAD(&msk->rtx_queue);
 	INIT_WORK(&msk->work, mptcp_worker);
 	__skb_queue_head_init(&msk->receive_queue);
-	__skb_queue_head_init(&msk->skb_tx_cache);
 	msk->out_of_order_queue = RB_ROOT;
 	msk->first_pending = NULL;
 	msk->wmem_reserved = 0;
 	msk->rmem_released = 0;
 	msk->tx_pending_data = 0;
-	msk->size_goal_cache = TCP_BASE_MSS;
 
 	msk->ack_hint = NULL;
 	msk->first = NULL;
@@ -2525,15 +2447,10 @@ static void __mptcp_clear_xmit(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	struct mptcp_data_frag *dtmp, *dfrag;
-	struct sk_buff *skb;
 
 	WRITE_ONCE(msk->first_pending, NULL);
 	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
 		dfrag_clear(sk, dfrag);
-	while ((skb = __skb_dequeue(&msk->skb_tx_cache)) != NULL) {
-		sk->sk_forward_alloc += skb->truesize;
-		kfree_skb(skb);
-	}
 }
 
 static void mptcp_cancel_work(struct sock *sk)

net/mptcp/protocol.h

@@ -245,9 +245,7 @@ struct mptcp_sock {
 	struct sk_buff  *ooo_last_skb;
 	struct rb_root  out_of_order_queue;
 	struct sk_buff_head receive_queue;
-	struct sk_buff_head skb_tx_cache;	/* this is wmem accounted */
 	int		tx_pending_data;
-	int		size_goal_cache;
 	struct list_head conn_list;
 	struct list_head rtx_queue;
 	struct mptcp_data_frag *first_pending;

net/mptcp/subflow.c

@@ -1046,8 +1046,10 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
 	/* we revalidate valid mapping on new skb, because we must ensure
 	 * the current skb is completely covered by the available mapping
 	 */
-	if (!validate_mapping(ssk, skb))
+	if (!validate_mapping(ssk, skb)) {
+		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
 		return MAPPING_INVALID;
+	}
 
 	skb_ext_del(skb, SKB_EXT_MPTCP);
 

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -680,6 +680,25 @@ run_tests_peekmode()
 	run_tests_lo "$ns1" "$ns1" dead:beef:1::1 1 "-P ${peekmode}"
 }
 
+display_time()
+{
+	time_end=$(date +%s)
+	time_run=$((time_end-time_start))
+
+	echo "Time: ${time_run} seconds"
+}
+
+stop_if_error()
+{
+	local msg="$1"
+
+	if [ ${ret} -ne 0 ]; then
+		echo "FAIL: ${msg}" 1>&2
+		display_time
+		exit ${ret}
+	fi
+}
+
 make_file "$cin" "client"
 make_file "$sin" "server"
 
@@ -687,6 +706,8 @@ check_mptcp_disabled
 
 check_mptcp_ulp_setsockopt
 
+stop_if_error "The kernel configuration is not valid for MPTCP"
+
 echo "INFO: validating network environment with pings"
 for sender in "$ns1" "$ns2" "$ns3" "$ns4";do
 	do_ping "$ns1" $sender 10.0.1.1
@@ -706,6 +727,8 @@ for sender in "$ns1" "$ns2" "$ns3" "$ns4";do
 	do_ping "$ns4" $sender dead:beef:3::1
 done
 
+stop_if_error "Could not even run ping tests"
+
 [ -n "$tc_loss" ] && tc -net "$ns2" qdisc add dev ns2eth3 root netem loss random $tc_loss delay ${tc_delay}ms
 echo -n "INFO: Using loss of $tc_loss "
 test "$tc_delay" -gt 0 && echo -n "delay $tc_delay ms "
@@ -733,18 +756,13 @@ echo "on ns3eth4"
 
 tc -net "$ns3" qdisc add dev ns3eth4 root netem delay ${reorder_delay}ms $tc_reorder
 
-for sender in $ns1 $ns2 $ns3 $ns4;do
-	run_tests_lo "$ns1" "$sender" 10.0.1.1 1
-	if [ $ret -ne 0 ] ;then
-		echo "FAIL: Could not even run loopback test" 1>&2
-		exit $ret
-	fi
-	run_tests_lo "$ns1" $sender dead:beef:1::1 1
-	if [ $ret -ne 0 ] ;then
-		echo "FAIL: Could not even run loopback v6 test" 2>&1
-		exit $ret
-	fi
+run_tests_lo "$ns1" "$ns1" 10.0.1.1 1
+stop_if_error "Could not even run loopback test"
+
+run_tests_lo "$ns1" "$ns1" dead:beef:1::1 1
+stop_if_error "Could not even run loopback v6 test"
 
+for sender in $ns1 $ns2 $ns3 $ns4;do
 	# ns1<->ns2 is not subject to reordering/tc delays. Use it to test
 	# mptcp syncookie support.
 	if [ $sender = $ns1 ]; then
@@ -753,6 +771,9 @@ for sender in $ns1 $ns2 $ns3 $ns4;do
 		ip netns exec "$ns2" sysctl -q net.ipv4.tcp_syncookies=1
 	fi
 
+	run_tests "$ns1" $sender 10.0.1.1
+	run_tests "$ns1" $sender dead:beef:1::1
+
 	run_tests "$ns2" $sender 10.0.1.2
 	run_tests "$ns2" $sender dead:beef:1::2
 	run_tests "$ns2" $sender 10.0.2.1
@@ -765,14 +786,13 @@ for sender in $ns1 $ns2 $ns3 $ns4;do
 
 	run_tests "$ns4" $sender 10.0.3.1
 	run_tests "$ns4" $sender dead:beef:3::1
+
+	stop_if_error "Tests with $sender as a sender have failed"
 done
 
 run_tests_peekmode "saveWithPeek"
 run_tests_peekmode "saveAfterPeek"
+stop_if_error "Tests with peek mode have failed"
 
-time_end=$(date +%s)
-time_run=$((time_end-time_start))
-
-echo "Time: ${time_run} seconds"
-
+display_time
 exit $ret