From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 994473FC8 for ; Fri, 24 Sep 2021 21:12:48 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10117"; a="246639632" X-IronPort-AV: E=Sophos;i="5.85,321,1624345200"; d="scan'208";a="246639632" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2021 14:12:44 -0700 X-IronPort-AV: E=Sophos;i="5.85,321,1624345200"; d="scan'208";a="704320278" Received: from mjmartin-desk2.amr.corp.intel.com (HELO mjmartin-desk2.intel.com) ([10.209.52.210]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2021 14:12:44 -0700 From: Mat Martineau To: netdev@vger.kernel.org Cc: Florian Westphal , davem@davemloft.net, kuba@kernel.org, matthieu.baerts@tessares.net, mptcp@lists.linux.dev, pabeni@redhat.com, Mat Martineau Subject: [PATCH net-next 1/5] mptcp: do not shrink snd_nxt when recovering Date: Fri, 24 Sep 2021 14:12:34 -0700 Message-Id: <20210924211238.162509-2-mathew.j.martineau@linux.intel.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210924211238.162509-1-mathew.j.martineau@linux.intel.com> References: <20210924211238.162509-1-mathew.j.martineau@linux.intel.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Florian Westphal When recovering after a link failure, snd_nxt should not be set to a lower value. Else, update of snd_nxt is broken because: msk->snd_nxt += ret; (where ret is number of bytes sent) assumes that snd_nxt always moves forward. After reduction, its possible that snd_nxt update gets out of sync: dfrag we just sent might have had a data sequence number even past recovery_snd_nxt. This change factors the common msk state update to a helper and updates snd_nxt based on the current dfrag data sequence number. The conditional is required for the recovery phase where we may re-transmit old dfrags that are before current snd_nxt. After this change, snd_nxt only moves forward and covers all in-sequence data that was transmitted. recovery_snd_nxt is retained to detect when recovery has completed. Fixes: 1e1d9d6f119c5 ("mptcp: handle pending data on closed subflow") Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau --- net/mptcp/options.c | 8 +++----- net/mptcp/protocol.c | 43 +++++++++++++++++++++++++++++++------------ 2 files changed, 34 insertions(+), 17 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index c41273cefc51..1ec6529c4326 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -1019,11 +1019,9 @@ static void ack_update_msk(struct mptcp_sock *msk, old_snd_una = msk->snd_una; new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); - /* ACK for data not even sent yet and even above recovery bound? Ignore.*/ - if (unlikely(after64(new_snd_una, snd_nxt))) { - if (!msk->recovery || after64(new_snd_una, msk->recovery_snd_nxt)) - new_snd_una = old_snd_una; - } + /* ACK for data not even sent yet? Ignore.*/ + if (unlikely(after64(new_snd_una, snd_nxt))) + new_snd_una = old_snd_una; new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7e5f76092b64..3d1757b8ef69 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1525,6 +1525,32 @@ static void mptcp_push_release(struct sock *sk, struct sock *ssk, release_sock(ssk); } +static void mptcp_update_post_push(struct mptcp_sock *msk, + struct mptcp_data_frag *dfrag, + u32 sent) +{ + u64 snd_nxt_new = dfrag->data_seq; + + dfrag->already_sent += sent; + + msk->snd_burst -= sent; + msk->tx_pending_data -= sent; + + snd_nxt_new += dfrag->already_sent; + + /* snd_nxt_new can be smaller than snd_nxt in case mptcp + * is recovering after a failover. In that event, this re-sends + * old segments. + * + * Thus compute snd_nxt_new candidate based on + * the dfrag->data_seq that was sent and the data + * that has been handed to the subflow for transmission + * and skip update in case it was old dfrag. + */ + if (likely(after64(snd_nxt_new, msk->snd_nxt))) + msk->snd_nxt = snd_nxt_new; +} + void __mptcp_push_pending(struct sock *sk, unsigned int flags) { struct sock *prev_ssk = NULL, *ssk = NULL; @@ -1568,12 +1594,10 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags) } info.sent += ret; - dfrag->already_sent += ret; - msk->snd_nxt += ret; - msk->snd_burst -= ret; - msk->tx_pending_data -= ret; copied += ret; len -= ret; + + mptcp_update_post_push(msk, dfrag, ret); } WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); } @@ -1626,13 +1650,11 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk) goto out; info.sent += ret; - dfrag->already_sent += ret; - msk->snd_nxt += ret; - msk->snd_burst -= ret; - msk->tx_pending_data -= ret; copied += ret; len -= ret; first = false; + + mptcp_update_post_push(msk, dfrag, ret); } WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); } @@ -2230,15 +2252,12 @@ bool __mptcp_retransmit_pending_data(struct sock *sk) return false; } - /* will accept ack for reijected data before re-sending them */ - if (!msk->recovery || after64(msk->snd_nxt, msk->recovery_snd_nxt)) - msk->recovery_snd_nxt = msk->snd_nxt; + msk->recovery_snd_nxt = msk->snd_nxt; msk->recovery = true; mptcp_data_unlock(sk); msk->first_pending = rtx_head; msk->tx_pending_data += msk->snd_nxt - rtx_head->data_seq; - msk->snd_nxt = rtx_head->data_seq; msk->snd_burst = 0; /* be sure to clear the "sent status" on all re-injected fragments */ -- 2.33.0