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Diffstat (limited to 'net/rds/threads.c')
| -rw-r--r-- | net/rds/threads.c | 311 |
1 files changed, 311 insertions, 0 deletions
diff --git a/net/rds/threads.c b/net/rds/threads.c new file mode 100644 index 000000000..1f424cbfc --- /dev/null +++ b/net/rds/threads.c @@ -0,0 +1,311 @@ +/* + * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved. + * + * This software is available to you under a choice of one of two + * licenses. You may choose to be licensed under the terms of the GNU + * General Public License (GPL) Version 2, available from the file + * COPYING in the main directory of this source tree, or the + * OpenIB.org BSD license below: + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * - Redistributions of source code must retain the above + * copyright notice, this list of conditions and the following + * disclaimer. + * + * - Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + * + */ +#include <linux/kernel.h> +#include <linux/random.h> +#include <linux/export.h> + +#include "rds.h" + +/* + * All of connection management is simplified by serializing it through + * work queues that execute in a connection managing thread. + * + * TCP wants to send acks through sendpage() in response to data_ready(), + * but it needs a process context to do so. + * + * The receive paths need to allocate but can't drop packets (!) so we have + * a thread around to block allocating if the receive fast path sees an + * allocation failure. + */ + +/* Grand Unified Theory of connection life cycle: + * At any point in time, the connection can be in one of these states: + * DOWN, CONNECTING, UP, DISCONNECTING, ERROR + * + * The following transitions are possible: + * ANY -> ERROR + * UP -> DISCONNECTING + * ERROR -> DISCONNECTING + * DISCONNECTING -> DOWN + * DOWN -> CONNECTING + * CONNECTING -> UP + * + * Transition to state DISCONNECTING/DOWN: + * - Inside the shutdown worker; synchronizes with xmit path + * through RDS_IN_XMIT, and with connection management callbacks + * via c_cm_lock. + * + * For receive callbacks, we rely on the underlying transport + * (TCP, IB/RDMA) to provide the necessary synchronisation. + */ +struct workqueue_struct *rds_wq; +EXPORT_SYMBOL_GPL(rds_wq); + +void rds_connect_path_complete(struct rds_conn_path *cp, int curr) +{ + if (!rds_conn_path_transition(cp, curr, RDS_CONN_UP)) { + printk(KERN_WARNING "%s: Cannot transition to state UP, " + "current state is %d\n", + __func__, + atomic_read(&cp->cp_state)); + rds_conn_path_drop(cp, false); + return; + } + + rdsdebug("conn %p for %pI6c to %pI6c complete\n", + cp->cp_conn, &cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr); + + cp->cp_reconnect_jiffies = 0; + set_bit(0, &cp->cp_conn->c_map_queued); + rcu_read_lock(); + if (!rds_destroy_pending(cp->cp_conn)) { + queue_delayed_work(rds_wq, &cp->cp_send_w, 0); + queue_delayed_work(rds_wq, &cp->cp_recv_w, 0); + } + rcu_read_unlock(); + cp->cp_conn->c_proposed_version = RDS_PROTOCOL_VERSION; +} +EXPORT_SYMBOL_GPL(rds_connect_path_complete); + +void rds_connect_complete(struct rds_connection *conn) +{ + rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING); +} +EXPORT_SYMBOL_GPL(rds_connect_complete); + +/* + * This random exponential backoff is relied on to eventually resolve racing + * connects. + * + * If connect attempts race then both parties drop both connections and come + * here to wait for a random amount of time before trying again. Eventually + * the backoff range will be so much greater than the time it takes to + * establish a connection that one of the pair will establish the connection + * before the other's random delay fires. + * + * Connection attempts that arrive while a connection is already established + * are also considered to be racing connects. This lets a connection from + * a rebooted machine replace an existing stale connection before the transport + * notices that the connection has failed. + * + * We should *always* start with a random backoff; otherwise a broken connection + * will always take several iterations to be re-established. + */ +void rds_queue_reconnect(struct rds_conn_path *cp) +{ + unsigned long rand; + struct rds_connection *conn = cp->cp_conn; + + rdsdebug("conn %p for %pI6c to %pI6c reconnect jiffies %lu\n", + conn, &conn->c_laddr, &conn->c_faddr, + cp->cp_reconnect_jiffies); + + /* let peer with smaller addr initiate reconnect, to avoid duels */ + if (conn->c_trans->t_type == RDS_TRANS_TCP && + rds_addr_cmp(&conn->c_laddr, &conn->c_faddr) >= 0) + return; + + set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags); + if (cp->cp_reconnect_jiffies == 0) { + cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies; + rcu_read_lock(); + if (!rds_destroy_pending(cp->cp_conn)) + queue_delayed_work(rds_wq, &cp->cp_conn_w, 0); + rcu_read_unlock(); + return; + } + + get_random_bytes(&rand, sizeof(rand)); + rdsdebug("%lu delay %lu ceil conn %p for %pI6c -> %pI6c\n", + rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies, + conn, &conn->c_laddr, &conn->c_faddr); + rcu_read_lock(); + if (!rds_destroy_pending(cp->cp_conn)) + queue_delayed_work(rds_wq, &cp->cp_conn_w, + rand % cp->cp_reconnect_jiffies); + rcu_read_unlock(); + + cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2, + rds_sysctl_reconnect_max_jiffies); +} + +void rds_connect_worker(struct work_struct *work) +{ + struct rds_conn_path *cp = container_of(work, + struct rds_conn_path, + cp_conn_w.work); + struct rds_connection *conn = cp->cp_conn; + int ret; + + if (cp->cp_index > 0 && + rds_addr_cmp(&cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr) >= 0) + return; + clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags); + ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING); + if (ret) { + ret = conn->c_trans->conn_path_connect(cp); + rdsdebug("conn %p for %pI6c to %pI6c dispatched, ret %d\n", + conn, &conn->c_laddr, &conn->c_faddr, ret); + + if (ret) { + if (rds_conn_path_transition(cp, + RDS_CONN_CONNECTING, + RDS_CONN_DOWN)) + rds_queue_reconnect(cp); + else + rds_conn_path_error(cp, "connect failed\n"); + } + } +} + +void rds_send_worker(struct work_struct *work) +{ + struct rds_conn_path *cp = container_of(work, + struct rds_conn_path, + cp_send_w.work); + int ret; + + if (rds_conn_path_state(cp) == RDS_CONN_UP) { + clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags); + ret = rds_send_xmit(cp); + cond_resched(); + rdsdebug("conn %p ret %d\n", cp->cp_conn, ret); + switch (ret) { + case -EAGAIN: + rds_stats_inc(s_send_immediate_retry); + queue_delayed_work(rds_wq, &cp->cp_send_w, 0); + break; + case -ENOMEM: + rds_stats_inc(s_send_delayed_retry); + queue_delayed_work(rds_wq, &cp->cp_send_w, 2); + break; + default: + break; + } + } +} + +void rds_recv_worker(struct work_struct *work) +{ + struct rds_conn_path *cp = container_of(work, + struct rds_conn_path, + cp_recv_w.work); + int ret; + + if (rds_conn_path_state(cp) == RDS_CONN_UP) { + ret = cp->cp_conn->c_trans->recv_path(cp); + rdsdebug("conn %p ret %d\n", cp->cp_conn, ret); + switch (ret) { + case -EAGAIN: + rds_stats_inc(s_recv_immediate_retry); + queue_delayed_work(rds_wq, &cp->cp_recv_w, 0); + break; + case -ENOMEM: + rds_stats_inc(s_recv_delayed_retry); + queue_delayed_work(rds_wq, &cp->cp_recv_w, 2); + break; + default: + break; + } + } +} + +void rds_shutdown_worker(struct work_struct *work) +{ + struct rds_conn_path *cp = container_of(work, + struct rds_conn_path, + cp_down_w); + + rds_conn_shutdown(cp); +} + +void rds_threads_exit(void) +{ + destroy_workqueue(rds_wq); +} + +int rds_threads_init(void) +{ + rds_wq = create_singlethread_workqueue("krdsd"); + if (!rds_wq) + return -ENOMEM; + + return 0; +} + +/* Compare two IPv6 addresses. Return 0 if the two addresses are equal. + * Return 1 if the first is greater. Return -1 if the second is greater. + */ +int rds_addr_cmp(const struct in6_addr *addr1, + const struct in6_addr *addr2) +{ +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + const __be64 *a1, *a2; + u64 x, y; + + a1 = (__be64 *)addr1; + a2 = (__be64 *)addr2; + + if (*a1 != *a2) { + if (be64_to_cpu(*a1) < be64_to_cpu(*a2)) + return -1; + else + return 1; + } else { + x = be64_to_cpu(*++a1); + y = be64_to_cpu(*++a2); + if (x < y) + return -1; + else if (x > y) + return 1; + else + return 0; + } +#else + u32 a, b; + int i; + + for (i = 0; i < 4; i++) { + if (addr1->s6_addr32[i] != addr2->s6_addr32[i]) { + a = ntohl(addr1->s6_addr32[i]); + b = ntohl(addr2->s6_addr32[i]); + if (a < b) + return -1; + else if (a > b) + return 1; + } + } + return 0; +#endif +} +EXPORT_SYMBOL_GPL(rds_addr_cmp); |