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33 #include <linux/kernel.h>
34 #include <linux/slab.h>
36 #include <net/net_namespace.h>
37 #include <net/netns/generic.h>
39 #include "rds_single_path.h"
43 static DEFINE_SPINLOCK(loop_conns_lock);
44 static LIST_HEAD(loop_conns);
45 static atomic_t rds_loop_unloading = ATOMIC_INIT(0);
47 static void rds_loop_set_unloading(void)
49 atomic_set(&rds_loop_unloading, 1);
52 static bool rds_loop_is_unloading(struct rds_connection *conn)
54 return atomic_read(&rds_loop_unloading) != 0;
58 * This 'loopback' transport is a special case for flows that originate
59 * and terminate on the same machine.
61 * Connection build-up notices if the destination address is thought of
62 * as a local address by a transport. At that time it decides to use the
63 * loopback transport instead of the bound transport of the sending socket.
65 * The loopback transport's sending path just hands the sent rds_message
66 * straight to the receiving path via an embedded rds_incoming.
70 * Usually a message transits both the sender and receiver's conns as it
71 * flows to the receiver. In the loopback case, though, the receive path
72 * is handed the sending conn so the sense of the addresses is reversed.
74 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
75 unsigned int hdr_off, unsigned int sg,
78 struct scatterlist *sgp = &rm->data.op_sg[sg];
79 int ret = sizeof(struct rds_header) +
80 be32_to_cpu(rm->m_inc.i_hdr.h_len);
82 /* Do not send cong updates to loopback */
83 if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
84 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
85 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
89 BUG_ON(hdr_off || sg || off);
91 rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
92 /* For the embedded inc. Matching put is in loop_inc_free() */
93 rds_message_addref(rm);
95 rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
98 rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
101 rds_inc_put(&rm->m_inc);
107 * See rds_loop_xmit(). Since our inc is embedded in the rm, we
108 * make sure the rm lives at least until the inc is done.
110 static void rds_loop_inc_free(struct rds_incoming *inc)
112 struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
117 /* we need to at least give the thread something to succeed */
118 static int rds_loop_recv_path(struct rds_conn_path *cp)
123 struct rds_loop_connection {
124 struct list_head loop_node;
125 struct rds_connection *conn;
129 * Even the loopback transport needs to keep track of its connections,
130 * so it can call rds_conn_destroy() on them on exit. N.B. there are
131 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
132 * multiple loopback conns allocated, although rather useless.
134 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
136 struct rds_loop_connection *lc;
139 lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
143 INIT_LIST_HEAD(&lc->loop_node);
145 conn->c_transport_data = lc;
147 spin_lock_irqsave(&loop_conns_lock, flags);
148 list_add_tail(&lc->loop_node, &loop_conns);
149 spin_unlock_irqrestore(&loop_conns_lock, flags);
154 static void rds_loop_conn_free(void *arg)
156 struct rds_loop_connection *lc = arg;
159 rdsdebug("lc %p\n", lc);
160 spin_lock_irqsave(&loop_conns_lock, flags);
161 list_del(&lc->loop_node);
162 spin_unlock_irqrestore(&loop_conns_lock, flags);
166 static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
168 rds_connect_complete(cp->cp_conn);
172 static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
176 void rds_loop_exit(void)
178 struct rds_loop_connection *lc, *_lc;
181 rds_loop_set_unloading();
183 /* avoid calling conn_destroy with irqs off */
184 spin_lock_irq(&loop_conns_lock);
185 list_splice(&loop_conns, &tmp_list);
186 INIT_LIST_HEAD(&loop_conns);
187 spin_unlock_irq(&loop_conns_lock);
189 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
190 WARN_ON(lc->conn->c_passive);
191 rds_conn_destroy(lc->conn);
195 static void rds_loop_kill_conns(struct net *net)
197 struct rds_loop_connection *lc, *_lc;
200 spin_lock_irq(&loop_conns_lock);
201 list_for_each_entry_safe(lc, _lc, &loop_conns, loop_node) {
202 struct net *c_net = read_pnet(&lc->conn->c_net);
206 list_move_tail(&lc->loop_node, &tmp_list);
208 spin_unlock_irq(&loop_conns_lock);
210 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
211 WARN_ON(lc->conn->c_passive);
212 rds_conn_destroy(lc->conn);
216 static void __net_exit rds_loop_exit_net(struct net *net)
218 rds_loop_kill_conns(net);
221 static struct pernet_operations rds_loop_net_ops = {
222 .exit = rds_loop_exit_net,
225 int rds_loop_net_init(void)
227 return register_pernet_device(&rds_loop_net_ops);
230 void rds_loop_net_exit(void)
232 unregister_pernet_device(&rds_loop_net_ops);
236 * This is missing .xmit_* because loop doesn't go through generic
237 * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and
238 * .laddr_check are missing because transport.c doesn't iterate over
239 * rds_loop_transport.
241 struct rds_transport rds_loop_transport = {
242 .xmit = rds_loop_xmit,
243 .recv_path = rds_loop_recv_path,
244 .conn_alloc = rds_loop_conn_alloc,
245 .conn_free = rds_loop_conn_free,
246 .conn_path_connect = rds_loop_conn_path_connect,
247 .conn_path_shutdown = rds_loop_conn_path_shutdown,
248 .inc_copy_to_user = rds_message_inc_copy_to_user,
249 .inc_free = rds_loop_inc_free,
250 .t_name = "loopback",
251 .t_type = RDS_TRANS_LOOP,
252 .t_unloading = rds_loop_is_unloading,