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-rw-r--r--net/rds/threads.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/net/rds/threads.c b/net/rds/threads.c
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index 000000000..e64f9e4c3
--- /dev/null
+++ b/net/rds/threads.c
@@ -0,0 +1,308 @@
+/*
+ * 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();
+}
+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);
+ 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);
+ 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);
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