From patchwork Thu Oct 28 05:16:26 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gerrit Renker X-Patchwork-Id: 69432 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id D2A21B70DE for ; Thu, 28 Oct 2010 16:17:02 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754206Ab0J1FQy (ORCPT ); Thu, 28 Oct 2010 01:16:54 -0400 Received: from dee.erg.abdn.ac.uk ([139.133.204.82]:39579 "EHLO erg.abdn.ac.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754124Ab0J1FQw (ORCPT ); Thu, 28 Oct 2010 01:16:52 -0400 Received: from laptev.erg.abdn.ac.uk (Debian-exim@ra-gerrit.erg.abdn.ac.uk [139.133.204.38]) by erg.abdn.ac.uk (8.13.4/8.13.4) with ESMTP id o9S5GSm9011567 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Thu, 28 Oct 2010 06:16:33 +0100 (BST) Received: from root by laptev.erg.abdn.ac.uk with local (Exim 4.69) (envelope-from ) id 1PBKqi-0001On-Lz; Thu, 28 Oct 2010 07:16:28 +0200 From: Gerrit Renker To: davem@davemloft.net Cc: dccp@vger.kernel.org, netdev@vger.kernel.org, Gerrit Renker Subject: [PATCH 2/4] dccp: Extend CCID packet dequeueing interface Date: Thu, 28 Oct 2010 07:16:26 +0200 Message-Id: <1288242988-5333-3-git-send-email-gerrit@erg.abdn.ac.uk> X-Mailer: git-send-email 1.6.0.rc2 In-Reply-To: <1288242988-5333-2-git-send-email-gerrit@erg.abdn.ac.uk> References: <1288242988-5333-1-git-send-email-gerrit@erg.abdn.ac.uk> <1288242988-5333-2-git-send-email-gerrit@erg.abdn.ac.uk> X-ERG-MailScanner: Found to be clean X-ERG-MailScanner-From: root@erg.abdn.ac.uk X-Spam-Status: No Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This extends the packet dequeuing interface of dccp_write_xmit() to allow 1. CCIDs to take care of timing when the next packet may be sent; 2. delayed sending (as before, with an inter-packet gap up to 65.535 seconds). The main purpose is to take CCID-2 out of its polling mode (when it is network- limited, it tries every millisecond to send, without interruption). The mode of operation for (2) is as follows: * new packet is enqueued via dccp_sendmsg() => dccp_write_xmit(), * ccid_hc_tx_send_packet() detects that it may not send (e.g. window full), * it signals this condition via `CCID_PACKET_WILL_DEQUEUE_LATER', * dccp_write_xmit() returns without further action; * after some time the wait-condition for CCID becomes true, * that CCID schedules the tasklet, * tasklet function calls ccid_hc_tx_send_packet() via dccp_write_xmit(), * since the wait-condition is now true, ccid_hc_tx_packet() returns "send now", * packet is sent, and possibly more (since dccp_write_xmit() loops). Code reuse: the taskled function calls dccp_write_xmit(), the timer function reduces to a wrapper around the same code. Signed-off-by: Gerrit Renker --- include/linux/dccp.h | 4 +- net/dccp/output.c | 118 ++++++++++++++++++++++++++++++------------------- net/dccp/timer.c | 25 ++++++----- 3 files changed, 89 insertions(+), 58 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/include/linux/dccp.h +++ b/include/linux/dccp.h @@ -462,7 +462,8 @@ struct dccp_ackvec; * @dccps_hc_rx_insert_options - receiver wants to add options when acking * @dccps_hc_tx_insert_options - sender wants to add options when sending * @dccps_server_timewait - server holds timewait state on close (RFC 4340, 8.3) - * @dccps_xmit_timer - timer for when CCID is not ready to send + * @dccps_xmitlet - tasklet scheduled by the TX CCID to dequeue data packets + * @dccps_xmit_timer - used by the TX CCID to delay sending (rate-based pacing) * @dccps_syn_rtt - RTT sample from Request/Response exchange (in usecs) */ struct dccp_sock { @@ -502,6 +503,7 @@ struct dccp_sock { __u8 dccps_hc_rx_insert_options:1; __u8 dccps_hc_tx_insert_options:1; __u8 dccps_server_timewait:1; + struct tasklet_struct dccps_xmitlet; struct timer_list dccps_xmit_timer; }; --- a/net/dccp/output.c +++ b/net/dccp/output.c @@ -254,63 +254,89 @@ do_interrupted: goto out; } +/** + * dccp_xmit_packet - Send data packet under control of CCID + * Transmits next-queued payload and informs CCID to account for the packet. + */ +static void dccp_xmit_packet(struct sock *sk) +{ + int err, len; + struct dccp_sock *dp = dccp_sk(sk); + struct sk_buff *skb = skb_dequeue(&sk->sk_write_queue); + + if (unlikely(skb == NULL)) + return; + len = skb->len; + + if (sk->sk_state == DCCP_PARTOPEN) { + const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD; + /* + * See 8.1.5 - Handshake Completion. + * + * For robustness we resend Confirm options until the client has + * entered OPEN. During the initial feature negotiation, the MPS + * is smaller than usual, reduced by the Change/Confirm options. + */ + if (!list_empty(&dp->dccps_featneg) && len > cur_mps) { + DCCP_WARN("Payload too large (%d) for featneg.\n", len); + dccp_send_ack(sk); + dccp_feat_list_purge(&dp->dccps_featneg); + } + + inet_csk_schedule_ack(sk); + inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, + inet_csk(sk)->icsk_rto, + DCCP_RTO_MAX); + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK; + } else if (dccp_ack_pending(sk)) { + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK; + } else { + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATA; + } + + err = dccp_transmit_skb(sk, skb); + if (err) + dccp_pr_debug("transmit_skb() returned err=%d\n", err); + /* + * Register this one as sent even if an error occurred. To the remote + * end a local packet drop is indistinguishable from network loss, i.e. + * any local drop will eventually be reported via receiver feedback. + */ + ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len); +} + void dccp_write_xmit(struct sock *sk, int block) { struct dccp_sock *dp = dccp_sk(sk); struct sk_buff *skb; while ((skb = skb_peek(&sk->sk_write_queue))) { - int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); + int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); - if (err > 0) { + switch (ccid_packet_dequeue_eval(rc)) { + case CCID_PACKET_WILL_DEQUEUE_LATER: + return; + case CCID_PACKET_DELAY: if (!block) { sk_reset_timer(sk, &dp->dccps_xmit_timer, - msecs_to_jiffies(err)+jiffies); + msecs_to_jiffies(rc)+jiffies); + return; + } + rc = dccp_wait_for_ccid(sk, skb, rc); + if (rc && rc != -EINTR) { + DCCP_BUG("err=%d after dccp_wait_for_ccid", rc); + skb_dequeue(&sk->sk_write_queue); + kfree_skb(skb); break; - } else - err = dccp_wait_for_ccid(sk, skb, err); - if (err && err != -EINTR) - DCCP_BUG("err=%d after dccp_wait_for_ccid", err); - } - - skb_dequeue(&sk->sk_write_queue); - if (err == 0) { - struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); - const int len = skb->len; - - if (sk->sk_state == DCCP_PARTOPEN) { - const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD; - /* - * See 8.1.5 - Handshake Completion. - * - * For robustness we resend Confirm options until the client has - * entered OPEN. During the initial feature negotiation, the MPS - * is smaller than usual, reduced by the Change/Confirm options. - */ - if (!list_empty(&dp->dccps_featneg) && len > cur_mps) { - DCCP_WARN("Payload too large (%d) for featneg.\n", len); - dccp_send_ack(sk); - dccp_feat_list_purge(&dp->dccps_featneg); - } - - inet_csk_schedule_ack(sk); - inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, - inet_csk(sk)->icsk_rto, - DCCP_RTO_MAX); - dcb->dccpd_type = DCCP_PKT_DATAACK; - } else if (dccp_ack_pending(sk)) - dcb->dccpd_type = DCCP_PKT_DATAACK; - else - dcb->dccpd_type = DCCP_PKT_DATA; - - err = dccp_transmit_skb(sk, skb); - ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len); - if (err) - DCCP_BUG("err=%d after ccid_hc_tx_packet_sent", - err); - } else { - dccp_pr_debug("packet discarded due to err=%d\n", err); + } + /* fall through */ + case CCID_PACKET_SEND_AT_ONCE: + dccp_xmit_packet(sk); + break; + case CCID_PACKET_ERR: + skb_dequeue(&sk->sk_write_queue); kfree_skb(skb); + dccp_pr_debug("packet discarded due to err=%d\n", rc); } } } --- a/net/dccp/timer.c +++ b/net/dccp/timer.c @@ -237,32 +237,35 @@ out: sock_put(sk); } -/* Transmit-delay timer: used by the CCIDs to delay actual send time */ -static void dccp_write_xmit_timer(unsigned long data) +/** + * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface + * See the comments above %ccid_dequeueing_decision for supported modes. + */ +static void dccp_write_xmitlet(unsigned long data) { struct sock *sk = (struct sock *)data; - struct dccp_sock *dp = dccp_sk(sk); bh_lock_sock(sk); if (sock_owned_by_user(sk)) - sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1); + sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1); else dccp_write_xmit(sk, 0); bh_unlock_sock(sk); - sock_put(sk); } -static void dccp_init_write_xmit_timer(struct sock *sk) +static void dccp_write_xmit_timer(unsigned long data) { - struct dccp_sock *dp = dccp_sk(sk); - - setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer, - (unsigned long)sk); + dccp_write_xmitlet(data); + sock_put((struct sock *)data); } void dccp_init_xmit_timers(struct sock *sk) { - dccp_init_write_xmit_timer(sk); + struct dccp_sock *dp = dccp_sk(sk); + + tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk); + setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer, + (unsigned long)sk); inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer, &dccp_keepalive_timer); }