[ofa-general] [PATCH 06/26] RDS: Connection handling
Andy Grover
andy.grover at oracle.com
Tue Feb 24 17:30:23 PST 2009
While arguably the fact that the underlying transport needs a
connection to convey RDS's datagrame reliably is not important
to rds proper, the transports implemented so far (IB and TCP)
have both been connection-oriented, and so the connection
state machine-related code is in the common rds code.
This patch also includes several work items, to handle connecting,
sending, receiving, and shutdown.
Signed-off-by: Andy Grover <andy.grover at oracle.com>
---
net/rds/connection.c | 487 ++++++++++++++++++++++++++++++++++++++++++++++++++
net/rds/threads.c | 265 +++++++++++++++++++++++++++
2 files changed, 752 insertions(+), 0 deletions(-)
create mode 100644 net/rds/connection.c
create mode 100644 net/rds/threads.c
diff --git a/net/rds/connection.c b/net/rds/connection.c
new file mode 100644
index 0000000..273f064
--- /dev/null
+++ b/net/rds/connection.c
@@ -0,0 +1,487 @@
+/*
+ * Copyright (c) 2006 Oracle. 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/list.h>
+#include <net/inet_hashtables.h>
+
+#include "rds.h"
+#include "loop.h"
+#include "rdma.h"
+
+#define RDS_CONNECTION_HASH_BITS 12
+#define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
+#define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
+
+/* converting this to RCU is a chore for another day.. */
+static DEFINE_SPINLOCK(rds_conn_lock);
+static unsigned long rds_conn_count;
+static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
+static struct kmem_cache *rds_conn_slab;
+
+static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
+{
+ /* Pass NULL, don't need struct net for hash */
+ unsigned long hash = inet_ehashfn(NULL,
+ be32_to_cpu(laddr), 0,
+ be32_to_cpu(faddr), 0);
+ return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
+}
+
+#define rds_conn_info_set(var, test, suffix) do { \
+ if (test) \
+ var |= RDS_INFO_CONNECTION_FLAG_##suffix; \
+} while (0)
+
+static inline int rds_conn_is_sending(struct rds_connection *conn)
+{
+ int ret = 0;
+
+ if (!mutex_trylock(&conn->c_send_lock))
+ ret = 1;
+ else
+ mutex_unlock(&conn->c_send_lock);
+
+ return ret;
+}
+
+static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
+ __be32 laddr, __be32 faddr,
+ struct rds_transport *trans)
+{
+ struct rds_connection *conn, *ret = NULL;
+ struct hlist_node *pos;
+
+ hlist_for_each_entry(conn, pos, head, c_hash_node) {
+ if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
+ conn->c_trans == trans) {
+ ret = conn;
+ break;
+ }
+ }
+ rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
+ &laddr, &faddr);
+ return ret;
+}
+
+/*
+ * This is called by transports as they're bringing down a connection.
+ * It clears partial message state so that the transport can start sending
+ * and receiving over this connection again in the future. It is up to
+ * the transport to have serialized this call with its send and recv.
+ */
+void rds_conn_reset(struct rds_connection *conn)
+{
+ rdsdebug("connection %pI4 to %pI4 reset\n",
+ &conn->c_laddr, &conn->c_faddr);
+
+ rds_stats_inc(s_conn_reset);
+ rds_send_reset(conn);
+ conn->c_flags = 0;
+
+ /* Do not clear next_rx_seq here, else we cannot distinguish
+ * retransmitted packets from new packets, and will hand all
+ * of them to the application. That is not consistent with the
+ * reliability guarantees of RDS. */
+}
+
+/*
+ * There is only every one 'conn' for a given pair of addresses in the
+ * system at a time. They contain messages to be retransmitted and so
+ * span the lifetime of the actual underlying transport connections.
+ *
+ * For now they are not garbage collected once they're created. They
+ * are torn down as the module is removed, if ever.
+ */
+static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
+ struct rds_transport *trans, gfp_t gfp,
+ int is_outgoing)
+{
+ struct rds_connection *conn, *tmp, *parent = NULL;
+ struct hlist_head *head = rds_conn_bucket(laddr, faddr);
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&rds_conn_lock, flags);
+ conn = rds_conn_lookup(head, laddr, faddr, trans);
+ if (conn
+ && conn->c_loopback
+ && conn->c_trans != &rds_loop_transport
+ && !is_outgoing) {
+ /* This is a looped back IB connection, and we're
+ * called by the code handling the incoming connect.
+ * We need a second connection object into which we
+ * can stick the other QP. */
+ parent = conn;
+ conn = parent->c_passive;
+ }
+ spin_unlock_irqrestore(&rds_conn_lock, flags);
+ if (conn)
+ goto out;
+
+ conn = kmem_cache_alloc(rds_conn_slab, gfp);
+ if (conn == NULL) {
+ conn = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ memset(conn, 0, sizeof(*conn));
+
+ INIT_HLIST_NODE(&conn->c_hash_node);
+ conn->c_version = RDS_PROTOCOL_3_0;
+ conn->c_laddr = laddr;
+ conn->c_faddr = faddr;
+ spin_lock_init(&conn->c_lock);
+ conn->c_next_tx_seq = 1;
+
+ mutex_init(&conn->c_send_lock);
+ INIT_LIST_HEAD(&conn->c_send_queue);
+ INIT_LIST_HEAD(&conn->c_retrans);
+
+ ret = rds_cong_get_maps(conn);
+ if (ret) {
+ kmem_cache_free(rds_conn_slab, conn);
+ conn = ERR_PTR(ret);
+ goto out;
+ }
+
+ /*
+ * This is where a connection becomes loopback. If *any* RDS sockets
+ * can bind to the destination address then we'd rather the messages
+ * flow through loopback rather than either transport.
+ */
+ if (rds_trans_get_preferred(faddr)) {
+ conn->c_loopback = 1;
+ if (is_outgoing && trans->t_prefer_loopback) {
+ /* "outgoing" connection - and the transport
+ * says it wants the connection handled by the
+ * loopback transport. This is what TCP does.
+ */
+ trans = &rds_loop_transport;
+ }
+ }
+
+ conn->c_trans = trans;
+
+ ret = trans->conn_alloc(conn, gfp);
+ if (ret) {
+ kmem_cache_free(rds_conn_slab, conn);
+ conn = ERR_PTR(ret);
+ goto out;
+ }
+
+ atomic_set(&conn->c_state, RDS_CONN_DOWN);
+ conn->c_reconnect_jiffies = 0;
+ INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
+ INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
+ INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
+ INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
+ mutex_init(&conn->c_cm_lock);
+ conn->c_flags = 0;
+
+ rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
+ conn, &laddr, &faddr,
+ trans->t_name ? trans->t_name : "[unknown]",
+ is_outgoing ? "(outgoing)" : "");
+
+ spin_lock_irqsave(&rds_conn_lock, flags);
+ if (parent == NULL) {
+ tmp = rds_conn_lookup(head, laddr, faddr, trans);
+ if (tmp == NULL)
+ hlist_add_head(&conn->c_hash_node, head);
+ } else {
+ tmp = parent->c_passive;
+ if (!tmp)
+ parent->c_passive = conn;
+ }
+
+ if (tmp) {
+ trans->conn_free(conn->c_transport_data);
+ kmem_cache_free(rds_conn_slab, conn);
+ conn = tmp;
+ } else {
+ rds_cong_add_conn(conn);
+ rds_conn_count++;
+ }
+
+ spin_unlock_irqrestore(&rds_conn_lock, flags);
+
+out:
+ return conn;
+}
+
+struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
+ struct rds_transport *trans, gfp_t gfp)
+{
+ return __rds_conn_create(laddr, faddr, trans, gfp, 0);
+}
+
+struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
+ struct rds_transport *trans, gfp_t gfp)
+{
+ return __rds_conn_create(laddr, faddr, trans, gfp, 1);
+}
+
+void rds_conn_destroy(struct rds_connection *conn)
+{
+ struct rds_message *rm, *rtmp;
+
+ rdsdebug("freeing conn %p for %pI4 -> "
+ "%pI4\n", conn, &conn->c_laddr,
+ &conn->c_faddr);
+
+ hlist_del_init(&conn->c_hash_node);
+
+ /* wait for the rds thread to shut it down */
+ atomic_set(&conn->c_state, RDS_CONN_ERROR);
+ cancel_delayed_work(&conn->c_conn_w);
+ queue_work(rds_wq, &conn->c_down_w);
+ flush_workqueue(rds_wq);
+
+ /* tear down queued messages */
+ list_for_each_entry_safe(rm, rtmp,
+ &conn->c_send_queue,
+ m_conn_item) {
+ list_del_init(&rm->m_conn_item);
+ BUG_ON(!list_empty(&rm->m_sock_item));
+ rds_message_put(rm);
+ }
+ if (conn->c_xmit_rm)
+ rds_message_put(conn->c_xmit_rm);
+
+ conn->c_trans->conn_free(conn->c_transport_data);
+
+ /*
+ * The congestion maps aren't freed up here. They're
+ * freed by rds_cong_exit() after all the connections
+ * have been freed.
+ */
+ rds_cong_remove_conn(conn);
+
+ BUG_ON(!list_empty(&conn->c_retrans));
+ kmem_cache_free(rds_conn_slab, conn);
+
+ rds_conn_count--;
+}
+
+static void rds_conn_message_info(struct socket *sock, unsigned int len,
+ struct rds_info_iterator *iter,
+ struct rds_info_lengths *lens,
+ int want_send)
+{
+ struct hlist_head *head;
+ struct hlist_node *pos;
+ struct list_head *list;
+ struct rds_connection *conn;
+ struct rds_message *rm;
+ unsigned long flags;
+ unsigned int total = 0;
+ size_t i;
+
+ len /= sizeof(struct rds_info_message);
+
+ spin_lock_irqsave(&rds_conn_lock, flags);
+
+ for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+ i++, head++) {
+ hlist_for_each_entry(conn, pos, head, c_hash_node) {
+ if (want_send)
+ list = &conn->c_send_queue;
+ else
+ list = &conn->c_retrans;
+
+ spin_lock(&conn->c_lock);
+
+ /* XXX too lazy to maintain counts.. */
+ list_for_each_entry(rm, list, m_conn_item) {
+ total++;
+ if (total <= len)
+ rds_inc_info_copy(&rm->m_inc, iter,
+ conn->c_laddr,
+ conn->c_faddr, 0);
+ }
+
+ spin_unlock(&conn->c_lock);
+ }
+ }
+
+ spin_unlock_irqrestore(&rds_conn_lock, flags);
+
+ lens->nr = total;
+ lens->each = sizeof(struct rds_info_message);
+}
+
+static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
+ struct rds_info_iterator *iter,
+ struct rds_info_lengths *lens)
+{
+ rds_conn_message_info(sock, len, iter, lens, 1);
+}
+
+static void rds_conn_message_info_retrans(struct socket *sock,
+ unsigned int len,
+ struct rds_info_iterator *iter,
+ struct rds_info_lengths *lens)
+{
+ rds_conn_message_info(sock, len, iter, lens, 0);
+}
+
+void rds_for_each_conn_info(struct socket *sock, unsigned int len,
+ struct rds_info_iterator *iter,
+ struct rds_info_lengths *lens,
+ int (*visitor)(struct rds_connection *, void *),
+ size_t item_len)
+{
+ uint64_t buffer[(item_len + 7) / 8];
+ struct hlist_head *head;
+ struct hlist_node *pos;
+ struct hlist_node *tmp;
+ struct rds_connection *conn;
+ unsigned long flags;
+ size_t i;
+
+ spin_lock_irqsave(&rds_conn_lock, flags);
+
+ lens->nr = 0;
+ lens->each = item_len;
+
+ for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+ i++, head++) {
+ hlist_for_each_entry_safe(conn, pos, tmp, head, c_hash_node) {
+
+ /* XXX no c_lock usage.. */
+ if (!visitor(conn, buffer))
+ continue;
+
+ /* We copy as much as we can fit in the buffer,
+ * but we count all items so that the caller
+ * can resize the buffer. */
+ if (len >= item_len) {
+ rds_info_copy(iter, buffer, item_len);
+ len -= item_len;
+ }
+ lens->nr++;
+ }
+ }
+
+ spin_unlock_irqrestore(&rds_conn_lock, flags);
+}
+
+static int rds_conn_info_visitor(struct rds_connection *conn,
+ void *buffer)
+{
+ struct rds_info_connection *cinfo = buffer;
+
+ cinfo->next_tx_seq = conn->c_next_tx_seq;
+ cinfo->next_rx_seq = conn->c_next_rx_seq;
+ cinfo->laddr = conn->c_laddr;
+ cinfo->faddr = conn->c_faddr;
+ strncpy(cinfo->transport, conn->c_trans->t_name,
+ sizeof(cinfo->transport));
+ cinfo->flags = 0;
+
+ rds_conn_info_set(cinfo->flags,
+ rds_conn_is_sending(conn), SENDING);
+ /* XXX Future: return the state rather than these funky bits */
+ rds_conn_info_set(cinfo->flags,
+ atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
+ CONNECTING);
+ rds_conn_info_set(cinfo->flags,
+ atomic_read(&conn->c_state) == RDS_CONN_UP,
+ CONNECTED);
+ return 1;
+}
+
+static void rds_conn_info(struct socket *sock, unsigned int len,
+ struct rds_info_iterator *iter,
+ struct rds_info_lengths *lens)
+{
+ rds_for_each_conn_info(sock, len, iter, lens,
+ rds_conn_info_visitor,
+ sizeof(struct rds_info_connection));
+}
+
+int __init rds_conn_init(void)
+{
+ rds_conn_slab = kmem_cache_create("rds_connection",
+ sizeof(struct rds_connection),
+ 0, 0, NULL);
+ if (rds_conn_slab == NULL)
+ return -ENOMEM;
+
+ rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
+ rds_info_register_func(RDS_INFO_SEND_MESSAGES,
+ rds_conn_message_info_send);
+ rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
+ rds_conn_message_info_retrans);
+
+ return 0;
+}
+
+void rds_conn_exit(void)
+{
+ rds_loop_exit();
+
+ WARN_ON(!hlist_empty(rds_conn_hash));
+
+ kmem_cache_destroy(rds_conn_slab);
+
+ rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
+ rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
+ rds_conn_message_info_send);
+ rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
+ rds_conn_message_info_retrans);
+}
+
+/*
+ * Force a disconnect
+ */
+void rds_conn_drop(struct rds_connection *conn)
+{
+ atomic_set(&conn->c_state, RDS_CONN_ERROR);
+ queue_work(rds_wq, &conn->c_down_w);
+}
+
+/*
+ * An error occurred on the connection
+ */
+void
+__rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ vprintk(fmt, ap);
+ va_end(ap);
+
+ rds_conn_drop(conn);
+}
diff --git a/net/rds/threads.c b/net/rds/threads.c
new file mode 100644
index 0000000..828a1bf
--- /dev/null
+++ b/net/rds/threads.c
@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2006 Oracle. 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 "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 c_send_lock, 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;
+
+void rds_connect_complete(struct rds_connection *conn)
+{
+ if (!rds_conn_transition(conn, RDS_CONN_CONNECTING, RDS_CONN_UP)) {
+ printk(KERN_WARNING "%s: Cannot transition to state UP, "
+ "current state is %d\n",
+ __func__,
+ atomic_read(&conn->c_state));
+ atomic_set(&conn->c_state, RDS_CONN_ERROR);
+ queue_work(rds_wq, &conn->c_down_w);
+ return;
+ }
+
+ rdsdebug("conn %p for %pI4 to %pI4 complete\n",
+ conn, &conn->c_laddr, &conn->c_faddr);
+
+ conn->c_reconnect_jiffies = 0;
+ set_bit(0, &conn->c_map_queued);
+ queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+ queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+}
+
+/*
+ * 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.
+ */
+static void rds_queue_reconnect(struct rds_connection *conn)
+{
+ unsigned long rand;
+
+ rdsdebug("conn %p for %pI4 to %pI4 reconnect jiffies %lu\n",
+ conn, &conn->c_laddr, &conn->c_faddr,
+ conn->c_reconnect_jiffies);
+
+ set_bit(RDS_RECONNECT_PENDING, &conn->c_flags);
+ if (conn->c_reconnect_jiffies == 0) {
+ conn->c_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
+ queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
+ return;
+ }
+
+ get_random_bytes(&rand, sizeof(rand));
+ rdsdebug("%lu delay %lu ceil conn %p for %pI4 -> %pI4\n",
+ rand % conn->c_reconnect_jiffies, conn->c_reconnect_jiffies,
+ conn, &conn->c_laddr, &conn->c_faddr);
+ queue_delayed_work(rds_wq, &conn->c_conn_w,
+ rand % conn->c_reconnect_jiffies);
+
+ conn->c_reconnect_jiffies = min(conn->c_reconnect_jiffies * 2,
+ rds_sysctl_reconnect_max_jiffies);
+}
+
+void rds_connect_worker(struct work_struct *work)
+{
+ struct rds_connection *conn = container_of(work, struct rds_connection, c_conn_w.work);
+ int ret;
+
+ clear_bit(RDS_RECONNECT_PENDING, &conn->c_flags);
+ if (rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
+ ret = conn->c_trans->conn_connect(conn);
+ rdsdebug("conn %p for %pI4 to %pI4 dispatched, ret %d\n",
+ conn, &conn->c_laddr, &conn->c_faddr, ret);
+
+ if (ret) {
+ if (rds_conn_transition(conn, RDS_CONN_CONNECTING, RDS_CONN_DOWN))
+ rds_queue_reconnect(conn);
+ else
+ rds_conn_error(conn, "RDS: connect failed\n");
+ }
+ }
+}
+
+void rds_shutdown_worker(struct work_struct *work)
+{
+ struct rds_connection *conn = container_of(work, struct rds_connection, c_down_w);
+
+ /* shut it down unless it's down already */
+ if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
+ /*
+ * Quiesce the connection mgmt handlers before we start tearing
+ * things down. We don't hold the mutex for the entire
+ * duration of the shutdown operation, else we may be
+ * deadlocking with the CM handler. Instead, the CM event
+ * handler is supposed to check for state DISCONNECTING
+ */
+ mutex_lock(&conn->c_cm_lock);
+ if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
+ && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
+ rds_conn_error(conn, "shutdown called in state %d\n",
+ atomic_read(&conn->c_state));
+ mutex_unlock(&conn->c_cm_lock);
+ return;
+ }
+ mutex_unlock(&conn->c_cm_lock);
+
+ mutex_lock(&conn->c_send_lock);
+ conn->c_trans->conn_shutdown(conn);
+ rds_conn_reset(conn);
+ mutex_unlock(&conn->c_send_lock);
+
+ if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
+ /* This can happen - eg when we're in the middle of tearing
+ * down the connection, and someone unloads the rds module.
+ * Quite reproduceable with loopback connections.
+ * Mostly harmless.
+ */
+ rds_conn_error(conn,
+ "%s: failed to transition to state DOWN, "
+ "current state is %d\n",
+ __func__,
+ atomic_read(&conn->c_state));
+ return;
+ }
+ }
+
+ /* Then reconnect if it's still live.
+ * The passive side of an IB loopback connection is never added
+ * to the conn hash, so we never trigger a reconnect on this
+ * conn - the reconnect is always triggered by the active peer. */
+ cancel_delayed_work(&conn->c_conn_w);
+ if (!hlist_unhashed(&conn->c_hash_node))
+ rds_queue_reconnect(conn);
+}
+
+void rds_send_worker(struct work_struct *work)
+{
+ struct rds_connection *conn = container_of(work, struct rds_connection, c_send_w.work);
+ int ret;
+
+ if (rds_conn_state(conn) == RDS_CONN_UP) {
+ ret = rds_send_xmit(conn);
+ rdsdebug("conn %p ret %d\n", conn, ret);
+ switch (ret) {
+ case -EAGAIN:
+ rds_stats_inc(s_send_immediate_retry);
+ queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+ break;
+ case -ENOMEM:
+ rds_stats_inc(s_send_delayed_retry);
+ queue_delayed_work(rds_wq, &conn->c_send_w, 2);
+ default:
+ break;
+ }
+ }
+}
+
+void rds_recv_worker(struct work_struct *work)
+{
+ struct rds_connection *conn = container_of(work, struct rds_connection, c_recv_w.work);
+ int ret;
+
+ if (rds_conn_state(conn) == RDS_CONN_UP) {
+ ret = conn->c_trans->recv(conn);
+ rdsdebug("conn %p ret %d\n", conn, ret);
+ switch (ret) {
+ case -EAGAIN:
+ rds_stats_inc(s_recv_immediate_retry);
+ queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+ break;
+ case -ENOMEM:
+ rds_stats_inc(s_recv_delayed_retry);
+ queue_delayed_work(rds_wq, &conn->c_recv_w, 2);
+ default:
+ break;
+ }
+ }
+}
+
+void rds_threads_exit(void)
+{
+ destroy_workqueue(rds_wq);
+}
+
+int __init rds_threads_init(void)
+{
+ rds_wq = create_singlethread_workqueue("krdsd");
+ if (rds_wq == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
--
1.5.6.3
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