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From: Mat Martineau <mathew.j.martineau@linux.intel.com>
To: netdev@vger.kernel.org, edumazet@google.com
Cc: Paolo Abeni <pabeni@redhat.com>,
	cpaasch@apple.com, fw@strlen.de, peter.krystad@linux.intel.com,
	dcaratti@redhat.com, matthieu.baerts@tessares.net
Subject: [RFC PATCH v2 35/45] mptcp: update per unacked sequence on pkt reception
Date: Wed,  2 Oct 2019 16:36:45 -0700	[thread overview]
Message-ID: <20191002233655.24323-36-mathew.j.martineau@linux.intel.com> (raw)
In-Reply-To: <20191002233655.24323-1-mathew.j.martineau@linux.intel.com>

From: Paolo Abeni <pabeni@redhat.com>

So that we keep per unacked sequence number consistent; since
we update per msk data, use an atomic64 cmpxcgh() to protect
against concurrent updates from multiple subflows.

Initialize the snd_una at connect()/accept() time.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/options.c  | 45 ++++++++++++++++++++++++++++++++++++++------
 net/mptcp/protocol.c |  2 ++
 net/mptcp/protocol.h |  1 +
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index ce298ecc64f5..2427fff98091 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -540,6 +540,39 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 	return false;
 }
 
+static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
+{
+	u32 old_ack32, cur_ack32;
+
+	if (use_64bit)
+		return cur_ack;
+
+	old_ack32 = (u32)old_ack;
+	cur_ack32 = (u32)cur_ack;
+	cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
+	if (unlikely(before(cur_ack32, old_ack32)))
+		return cur_ack + (1LL << 32);
+	return cur_ack;
+}
+
+void update_una(struct mptcp_sock *msk, struct mptcp_options_received *mp_opt)
+{
+	u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
+
+	/* avoid ack expansion on update conflict, to reduce the risk of
+	 * wrongly expanding to a future ack sequence number, which is way
+	 * more dangerous than missing an ack
+	 */
+	new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
+	while (after64(new_snd_una, old_snd_una)) {
+		snd_una = old_snd_una;
+		old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
+					       new_snd_una);
+		if (old_snd_una == snd_una)
+			break;
+	}
+}
+
 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 			    struct tcp_options_received *opt_rx)
 {
@@ -563,6 +596,12 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 	if (!mp_opt->dss)
 		return;
 
+	/* we can't wait for recvmsg() to update the ack_seq, otherwise
+	 * monodirectional flows will stuck
+	 */
+	if (msk && mp_opt->use_ack)
+		update_una(msk, mp_opt);
+
 	mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 	if (!mpext)
 		return;
@@ -579,12 +618,6 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 		mpext->use_checksum = mp_opt->use_checksum;
 	}
 
-	if (mp_opt->use_ack) {
-		mpext->data_ack = mp_opt->data_ack;
-		mpext->use_ack = 1;
-		mpext->ack64 = mp_opt->ack64;
-	}
-
 	mpext->data_fin = mp_opt->data_fin;
 
 	if (msk)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index c8ee20963887..2c64435aedd8 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -688,6 +688,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
 
 		mptcp_crypto_key_sha1(msk->remote_key, NULL, &ack_seq);
 		msk->write_seq = subflow->idsn + 1;
+		atomic64_set(&msk->snd_una, msk->write_seq);
 		ack_seq++;
 		msk->ack_seq = ack_seq;
 		subflow->map_seq = ack_seq;
@@ -822,6 +823,7 @@ void mptcp_finish_connect(struct sock *sk, int mp_capable)
 
 		mptcp_crypto_key_sha1(msk->remote_key, NULL, &ack_seq);
 		msk->write_seq = subflow->idsn + 1;
+		atomic64_set(&msk->snd_una, msk->write_seq);
 		ack_seq++;
 		msk->ack_seq = ack_seq;
 		subflow->map_seq = ack_seq;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 56df4f46f313..45646e38aa4c 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -119,6 +119,7 @@ struct mptcp_sock {
 	u64		remote_key;
 	u64		write_seq;
 	u64		ack_seq;
+	atomic64_t	snd_una;
 	u32		token;
 	unsigned long	flags;
 	u16		dport;
-- 
2.23.0


  parent reply	other threads:[~2019-10-02 23:38 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-02 23:36 [RFC PATCH v2 00/45] Multipath TCP Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 01/45] tcp: Add MPTCP option number Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 02/45] net: Make sock protocol value checks more specific Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 03/45] sock: Make sk_protocol a 16-bit value Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 04/45] tcp: Define IPPROTO_MPTCP Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 05/45] mptcp: Add MPTCP socket stubs Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 06/45] mptcp: Handle MPTCP TCP options Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 07/45] mptcp: Associate MPTCP context with TCP socket Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 08/45] tcp: Expose tcp struct and routine for MPTCP Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 09/45] mptcp: Handle MP_CAPABLE options for outgoing connections Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 10/45] mptcp: add mptcp_poll Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 11/45] tcp, ulp: Add clone operation to tcp_ulp_ops Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 12/45] mptcp: Create SUBFLOW socket for incoming connections Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 13/45] mptcp: Add key generation and token tree Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 14/45] mptcp: Add shutdown() socket operation Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 15/45] mptcp: Add setsockopt()/getsockopt() socket operations Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 16/45] tcp: clean ext on tx recycle Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 17/45] mptcp: Add MPTCP to skb extensions Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 18/45] tcp: Prevent coalesce/collapse when skb has MPTCP extensions Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 19/45] tcp: Export low-level TCP functions Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 20/45] mptcp: Write MPTCP DSS headers to outgoing data packets Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 21/45] mptcp: Implement MPTCP receive path Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 22/45] mptcp: use sk_page_frag() in sendmsg Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 23/45] mptcp: sendmsg() do spool all the provided data Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 24/45] mptcp: allow collapsing consecutive sendpages on the same substream Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 25/45] tcp: Check for filled TCP option space before SACK Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 26/45] mptcp: Add path manager interface Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 27/45] mptcp: Add ADD_ADDR handling Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 28/45] mptcp: Add handling of incoming MP_JOIN requests Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 29/45] mptcp: harmonize locking on all socket operations Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 30/45] mptcp: new sysctl to control the activation per NS Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 31/45] mptcp: add basic kselftest for mptcp Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 32/45] mptcp: Add handling of outgoing MP_JOIN requests Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 33/45] mptcp: Implement path manager interface commands Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 34/45] mptcp: Make MPTCP socket block/wakeup ignore sk_receive_queue Mat Martineau
2019-10-02 23:36 ` Mat Martineau [this message]
2019-10-02 23:36 ` [RFC PATCH v2 36/45] mptcp: queue data for mptcp level retransmission Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 37/45] mptcp: introduce MPTCP retransmission timer Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 38/45] mptcp: implement memory accounting for mptcp rtx queue Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 39/45] mptcp: rework mptcp_sendmsg_frag to accept optional dfrag Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 40/45] mptcp: implement and use MPTCP-level retransmission Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 41/45] selftests: mptcp: make tc delays random Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 42/45] selftests: mptcp: extend mptcp_connect tool for ipv6 family Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 43/45] selftests: mptcp: add accept/getpeer checks Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 44/45] selftests: mptcp: add ipv6 connectivity Mat Martineau
2019-10-02 23:36 ` [RFC PATCH v2 45/45] selftests: mptcp: random ethtool tweaking Mat Martineau
2019-10-02 23:53 ` [RFC PATCH v2 00/45] Multipath TCP Mat Martineau
2019-10-03  0:12 ` David Miller
2019-10-03  0:27   ` Mat Martineau

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