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Linux/net/rds/loop.c

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  1 /*
  2  * Copyright (c) 2006 Oracle.  All rights reserved.
  3  *
  4  * This software is available to you under a choice of one of two
  5  * licenses.  You may choose to be licensed under the terms of the GNU
  6  * General Public License (GPL) Version 2, available from the file
  7  * COPYING in the main directory of this source tree, or the
  8  * OpenIB.org BSD license below:
  9  *
 10  *     Redistribution and use in source and binary forms, with or
 11  *     without modification, are permitted provided that the following
 12  *     conditions are met:
 13  *
 14  *      - Redistributions of source code must retain the above
 15  *        copyright notice, this list of conditions and the following
 16  *        disclaimer.
 17  *
 18  *      - Redistributions in binary form must reproduce the above
 19  *        copyright notice, this list of conditions and the following
 20  *        disclaimer in the documentation and/or other materials
 21  *        provided with the distribution.
 22  *
 23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 30  * SOFTWARE.
 31  *
 32  */
 33 #include <linux/kernel.h>
 34 #include <linux/slab.h>
 35 #include <linux/in.h>
 36 
 37 #include "rds_single_path.h"
 38 #include "rds.h"
 39 #include "loop.h"
 40 
 41 static DEFINE_SPINLOCK(loop_conns_lock);
 42 static LIST_HEAD(loop_conns);
 43 
 44 /*
 45  * This 'loopback' transport is a special case for flows that originate
 46  * and terminate on the same machine.
 47  *
 48  * Connection build-up notices if the destination address is thought of
 49  * as a local address by a transport.  At that time it decides to use the
 50  * loopback transport instead of the bound transport of the sending socket.
 51  *
 52  * The loopback transport's sending path just hands the sent rds_message
 53  * straight to the receiving path via an embedded rds_incoming.
 54  */
 55 
 56 /*
 57  * Usually a message transits both the sender and receiver's conns as it
 58  * flows to the receiver.  In the loopback case, though, the receive path
 59  * is handed the sending conn so the sense of the addresses is reversed.
 60  */
 61 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
 62                          unsigned int hdr_off, unsigned int sg,
 63                          unsigned int off)
 64 {
 65         struct scatterlist *sgp = &rm->data.op_sg[sg];
 66         int ret = sizeof(struct rds_header) +
 67                         be32_to_cpu(rm->m_inc.i_hdr.h_len);
 68 
 69         /* Do not send cong updates to loopback */
 70         if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
 71                 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
 72                 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
 73                 goto out;
 74         }
 75 
 76         BUG_ON(hdr_off || sg || off);
 77 
 78         rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
 79         /* For the embedded inc. Matching put is in loop_inc_free() */
 80         rds_message_addref(rm);
 81 
 82         rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
 83                           GFP_KERNEL);
 84 
 85         rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
 86                             NULL);
 87 
 88         rds_inc_put(&rm->m_inc);
 89 out:
 90         return ret;
 91 }
 92 
 93 /*
 94  * See rds_loop_xmit(). Since our inc is embedded in the rm, we
 95  * make sure the rm lives at least until the inc is done.
 96  */
 97 static void rds_loop_inc_free(struct rds_incoming *inc)
 98 {
 99         struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
100 
101         rds_message_put(rm);
102 }
103 
104 /* we need to at least give the thread something to succeed */
105 static int rds_loop_recv_path(struct rds_conn_path *cp)
106 {
107         return 0;
108 }
109 
110 struct rds_loop_connection {
111         struct list_head loop_node;
112         struct rds_connection *conn;
113 };
114 
115 /*
116  * Even the loopback transport needs to keep track of its connections,
117  * so it can call rds_conn_destroy() on them on exit. N.B. there are
118  * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
119  * multiple loopback conns allocated, although rather useless.
120  */
121 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
122 {
123         struct rds_loop_connection *lc;
124         unsigned long flags;
125 
126         lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
127         if (!lc)
128                 return -ENOMEM;
129 
130         INIT_LIST_HEAD(&lc->loop_node);
131         lc->conn = conn;
132         conn->c_transport_data = lc;
133 
134         spin_lock_irqsave(&loop_conns_lock, flags);
135         list_add_tail(&lc->loop_node, &loop_conns);
136         spin_unlock_irqrestore(&loop_conns_lock, flags);
137 
138         return 0;
139 }
140 
141 static void rds_loop_conn_free(void *arg)
142 {
143         struct rds_loop_connection *lc = arg;
144         unsigned long flags;
145 
146         rdsdebug("lc %p\n", lc);
147         spin_lock_irqsave(&loop_conns_lock, flags);
148         list_del(&lc->loop_node);
149         spin_unlock_irqrestore(&loop_conns_lock, flags);
150         kfree(lc);
151 }
152 
153 static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
154 {
155         rds_connect_complete(cp->cp_conn);
156         return 0;
157 }
158 
159 static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
160 {
161 }
162 
163 void rds_loop_exit(void)
164 {
165         struct rds_loop_connection *lc, *_lc;
166         LIST_HEAD(tmp_list);
167 
168         /* avoid calling conn_destroy with irqs off */
169         spin_lock_irq(&loop_conns_lock);
170         list_splice(&loop_conns, &tmp_list);
171         INIT_LIST_HEAD(&loop_conns);
172         spin_unlock_irq(&loop_conns_lock);
173 
174         list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
175                 WARN_ON(lc->conn->c_passive);
176                 rds_conn_destroy(lc->conn);
177         }
178 }
179 
180 /*
181  * This is missing .xmit_* because loop doesn't go through generic
182  * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
183  * .laddr_check are missing because transport.c doesn't iterate over
184  * rds_loop_transport.
185  */
186 struct rds_transport rds_loop_transport = {
187         .xmit                   = rds_loop_xmit,
188         .recv_path              = rds_loop_recv_path,
189         .conn_alloc             = rds_loop_conn_alloc,
190         .conn_free              = rds_loop_conn_free,
191         .conn_path_connect      = rds_loop_conn_path_connect,
192         .conn_path_shutdown     = rds_loop_conn_path_shutdown,
193         .inc_copy_to_user       = rds_message_inc_copy_to_user,
194         .inc_free               = rds_loop_inc_free,
195         .t_name                 = "loopback",
196 };
197 

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