![Sowmini Varadhan](/assets/img/avatar_default.png)
Use RDS probe-ping to compute how many paths may be used with the peer, and to synchronously start the multiple paths. If mprds is supported, hash outgoing traffic to one of multiple paths in rds_sendmsg() when multipath RDS is supported by the transport. CC: Santosh Shilimkar <santosh.shilimkar@oracle.com> Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
252 lines
7.5 KiB
C
252 lines
7.5 KiB
C
/*
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* Copyright (c) 2006 Oracle. 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);
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return;
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}
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rdsdebug("conn %p for %pI4 to %pI4 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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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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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 %pI4 to %pI4 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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conn->c_laddr > conn->c_faddr)
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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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queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
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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 %pI4 -> %pI4\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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queue_delayed_work(rds_wq, &cp->cp_conn_w,
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rand % cp->cp_reconnect_jiffies);
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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 > 1 && cp->cp_conn->c_laddr > cp->cp_conn->c_faddr)
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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 %pI4 to %pI4 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,
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"RDS: 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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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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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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