312 lines
8.8 KiB
C
312 lines
8.8 KiB
C
/*
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* Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/random.h>
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#include <linux/export.h>
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#include "rds.h"
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/*
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* All of connection management is simplified by serializing it through
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* work queues that execute in a connection managing thread.
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*
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* TCP wants to send acks through sendpage() in response to data_ready(),
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* but it needs a process context to do so.
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*
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* The receive paths need to allocate but can't drop packets (!) so we have
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* a thread around to block allocating if the receive fast path sees an
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* allocation failure.
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*/
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/* Grand Unified Theory of connection life cycle:
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* At any point in time, the connection can be in one of these states:
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* DOWN, CONNECTING, UP, DISCONNECTING, ERROR
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*
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* The following transitions are possible:
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* ANY -> ERROR
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* UP -> DISCONNECTING
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* ERROR -> DISCONNECTING
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* DISCONNECTING -> DOWN
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* DOWN -> CONNECTING
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* CONNECTING -> UP
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*
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* Transition to state DISCONNECTING/DOWN:
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* - Inside the shutdown worker; synchronizes with xmit path
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* through RDS_IN_XMIT, and with connection management callbacks
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* via c_cm_lock.
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*
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* For receive callbacks, we rely on the underlying transport
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* (TCP, IB/RDMA) to provide the necessary synchronisation.
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*/
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struct workqueue_struct *rds_wq;
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EXPORT_SYMBOL_GPL(rds_wq);
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void rds_connect_path_complete(struct rds_conn_path *cp, int curr)
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{
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if (!rds_conn_path_transition(cp, curr, RDS_CONN_UP)) {
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printk(KERN_WARNING "%s: Cannot transition to state UP, "
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"current state is %d\n",
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__func__,
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atomic_read(&cp->cp_state));
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rds_conn_path_drop(cp, false);
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return;
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}
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rdsdebug("conn %p for %pI6c to %pI6c complete\n",
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cp->cp_conn, &cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr);
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cp->cp_reconnect_jiffies = 0;
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set_bit(0, &cp->cp_conn->c_map_queued);
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rcu_read_lock();
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if (!rds_destroy_pending(cp->cp_conn)) {
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queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
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queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
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}
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rcu_read_unlock();
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cp->cp_conn->c_proposed_version = RDS_PROTOCOL_VERSION;
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}
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EXPORT_SYMBOL_GPL(rds_connect_path_complete);
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void rds_connect_complete(struct rds_connection *conn)
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{
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rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING);
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}
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EXPORT_SYMBOL_GPL(rds_connect_complete);
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/*
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* This random exponential backoff is relied on to eventually resolve racing
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* connects.
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*
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* If connect attempts race then both parties drop both connections and come
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* here to wait for a random amount of time before trying again. Eventually
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* the backoff range will be so much greater than the time it takes to
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* establish a connection that one of the pair will establish the connection
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* before the other's random delay fires.
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*
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* Connection attempts that arrive while a connection is already established
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* are also considered to be racing connects. This lets a connection from
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* a rebooted machine replace an existing stale connection before the transport
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* notices that the connection has failed.
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*
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* We should *always* start with a random backoff; otherwise a broken connection
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* will always take several iterations to be re-established.
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*/
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void rds_queue_reconnect(struct rds_conn_path *cp)
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{
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unsigned long rand;
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struct rds_connection *conn = cp->cp_conn;
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rdsdebug("conn %p for %pI6c to %pI6c reconnect jiffies %lu\n",
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conn, &conn->c_laddr, &conn->c_faddr,
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cp->cp_reconnect_jiffies);
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/* let peer with smaller addr initiate reconnect, to avoid duels */
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if (conn->c_trans->t_type == RDS_TRANS_TCP &&
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rds_addr_cmp(&conn->c_laddr, &conn->c_faddr) >= 0)
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return;
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set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
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if (cp->cp_reconnect_jiffies == 0) {
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cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
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rcu_read_lock();
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if (!rds_destroy_pending(cp->cp_conn))
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queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
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rcu_read_unlock();
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return;
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}
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get_random_bytes(&rand, sizeof(rand));
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rdsdebug("%lu delay %lu ceil conn %p for %pI6c -> %pI6c\n",
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rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies,
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conn, &conn->c_laddr, &conn->c_faddr);
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rcu_read_lock();
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if (!rds_destroy_pending(cp->cp_conn))
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queue_delayed_work(rds_wq, &cp->cp_conn_w,
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rand % cp->cp_reconnect_jiffies);
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rcu_read_unlock();
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cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2,
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rds_sysctl_reconnect_max_jiffies);
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}
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void rds_connect_worker(struct work_struct *work)
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{
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struct rds_conn_path *cp = container_of(work,
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struct rds_conn_path,
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cp_conn_w.work);
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struct rds_connection *conn = cp->cp_conn;
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int ret;
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if (cp->cp_index > 0 &&
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rds_addr_cmp(&cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr) >= 0)
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return;
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clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
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ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
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if (ret) {
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ret = conn->c_trans->conn_path_connect(cp);
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rdsdebug("conn %p for %pI6c to %pI6c dispatched, ret %d\n",
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conn, &conn->c_laddr, &conn->c_faddr, ret);
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if (ret) {
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if (rds_conn_path_transition(cp,
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RDS_CONN_CONNECTING,
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RDS_CONN_DOWN))
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rds_queue_reconnect(cp);
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else
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rds_conn_path_error(cp, "connect failed\n");
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}
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}
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}
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void rds_send_worker(struct work_struct *work)
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{
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struct rds_conn_path *cp = container_of(work,
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struct rds_conn_path,
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cp_send_w.work);
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int ret;
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if (rds_conn_path_state(cp) == RDS_CONN_UP) {
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clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags);
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ret = rds_send_xmit(cp);
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cond_resched();
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rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
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switch (ret) {
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case -EAGAIN:
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rds_stats_inc(s_send_immediate_retry);
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queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
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break;
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case -ENOMEM:
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rds_stats_inc(s_send_delayed_retry);
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queue_delayed_work(rds_wq, &cp->cp_send_w, 2);
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break;
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default:
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break;
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}
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}
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}
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void rds_recv_worker(struct work_struct *work)
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{
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struct rds_conn_path *cp = container_of(work,
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struct rds_conn_path,
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cp_recv_w.work);
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int ret;
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if (rds_conn_path_state(cp) == RDS_CONN_UP) {
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ret = cp->cp_conn->c_trans->recv_path(cp);
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rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
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switch (ret) {
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case -EAGAIN:
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rds_stats_inc(s_recv_immediate_retry);
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queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
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break;
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case -ENOMEM:
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rds_stats_inc(s_recv_delayed_retry);
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queue_delayed_work(rds_wq, &cp->cp_recv_w, 2);
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break;
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default:
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break;
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}
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}
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}
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void rds_shutdown_worker(struct work_struct *work)
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{
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struct rds_conn_path *cp = container_of(work,
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struct rds_conn_path,
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cp_down_w);
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rds_conn_shutdown(cp);
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}
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void rds_threads_exit(void)
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{
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destroy_workqueue(rds_wq);
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}
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int rds_threads_init(void)
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{
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rds_wq = create_singlethread_workqueue("krdsd");
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if (!rds_wq)
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return -ENOMEM;
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return 0;
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}
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/* Compare two IPv6 addresses. Return 0 if the two addresses are equal.
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* Return 1 if the first is greater. Return -1 if the second is greater.
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*/
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int rds_addr_cmp(const struct in6_addr *addr1,
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const struct in6_addr *addr2)
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{
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#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
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const __be64 *a1, *a2;
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u64 x, y;
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a1 = (__be64 *)addr1;
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a2 = (__be64 *)addr2;
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if (*a1 != *a2) {
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if (be64_to_cpu(*a1) < be64_to_cpu(*a2))
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return -1;
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else
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return 1;
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} else {
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x = be64_to_cpu(*++a1);
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y = be64_to_cpu(*++a2);
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if (x < y)
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return -1;
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else if (x > y)
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return 1;
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else
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return 0;
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}
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#else
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u32 a, b;
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int i;
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for (i = 0; i < 4; i++) {
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if (addr1->s6_addr32[i] != addr2->s6_addr32[i]) {
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a = ntohl(addr1->s6_addr32[i]);
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b = ntohl(addr2->s6_addr32[i]);
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if (a < b)
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return -1;
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else if (a > b)
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return 1;
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}
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}
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return 0;
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#endif
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}
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EXPORT_SYMBOL_GPL(rds_addr_cmp);
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