drivers/staging/lustre/lustre/ptlrpc/connection.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  */
  36
  37 #define DEBUG_SUBSYSTEM S_RPC
  38 #include "../include/obd_support.h"
  39 #include "../include/obd_class.h"
  40 #include "../include/lustre_net.h"
  41
  42 #include "ptlrpc_internal.h"
  43
  44 static struct cfs_hash *conn_hash;
  45 static struct cfs_hash_ops conn_hash_ops;
  46
  47 struct ptlrpc_connection *
  48 ptlrpc_connection_get(lnet_process_id_t peer, lnet_nid_t self,
  49                       struct obd_uuid *uuid)
  50 {
  51         struct ptlrpc_connection *conn, *conn2;
  52
  53         conn = cfs_hash_lookup(conn_hash, &peer);
  54         if (conn)
  55                 goto out;
  56
  57         conn = kzalloc(sizeof(*conn), GFP_NOFS);
  58         if (!conn)
  59                 return NULL;
  60
  61         conn->c_peer = peer;
  62         conn->c_self = self;
  63         INIT_HLIST_NODE(&conn->c_hash);
  64         atomic_set(&conn->c_refcount, 1);
  65         if (uuid)
  66                 obd_str2uuid(&conn->c_remote_uuid, uuid->uuid);
  67
  68         /*
  69          * Add the newly created conn to the hash, on key collision we
  70          * lost a racing addition and must destroy our newly allocated
  71          * connection.  The object which exists in the has will be
  72          * returned and may be compared against out object.
  73          */
  74         /* In the function below, .hs_keycmp resolves to
  75          * conn_keycmp()
  76          */
  77         /* coverity[overrun-buffer-val] */
  78         conn2 = cfs_hash_findadd_unique(conn_hash, &peer, &conn->c_hash);
  79         if (conn != conn2) {
  80                 kfree(conn);
  81                 conn = conn2;
  82         }
  83 out:
  84         CDEBUG(D_INFO, "conn=%p refcount %d to %s\n",
  85                conn, atomic_read(&conn->c_refcount),
  86                libcfs_nid2str(conn->c_peer.nid));
  87         return conn;
  88 }
  89 EXPORT_SYMBOL(ptlrpc_connection_get);
  90
  91 int ptlrpc_connection_put(struct ptlrpc_connection *conn)
  92 {
  93         int rc = 0;
  94
  95         if (!conn)
  96                 return rc;
  97
  98         LASSERT(atomic_read(&conn->c_refcount) > 1);
  99
 100         /*
 101          * We do not remove connection from hashtable and
 102          * do not free it even if last caller released ref,
 103          * as we want to have it cached for the case it is
 104          * needed again.
 105          *
 106          * Deallocating it and later creating new connection
 107          * again would be wastful. This way we also avoid
 108          * expensive locking to protect things from get/put
 109          * race when found cached connection is freed by
 110          * ptlrpc_connection_put().
 111          *
 112          * It will be freed later in module unload time,
 113          * when ptlrpc_connection_fini()->lh_exit->conn_exit()
 114          * path is called.
 115          */
 116         if (atomic_dec_return(&conn->c_refcount) == 1)
 117                 rc = 1;
 118
 119         CDEBUG(D_INFO, "PUT conn=%p refcount %d to %s\n",
 120                conn, atomic_read(&conn->c_refcount),
 121                libcfs_nid2str(conn->c_peer.nid));
 122
 123         return rc;
 124 }
 125 EXPORT_SYMBOL(ptlrpc_connection_put);
 126
 127 struct ptlrpc_connection *
 128 ptlrpc_connection_addref(struct ptlrpc_connection *conn)
 129 {
 130         atomic_inc(&conn->c_refcount);
 131         CDEBUG(D_INFO, "conn=%p refcount %d to %s\n",
 132                conn, atomic_read(&conn->c_refcount),
 133                libcfs_nid2str(conn->c_peer.nid));
 134
 135         return conn;
 136 }
 137 EXPORT_SYMBOL(ptlrpc_connection_addref);
 138
 139 int ptlrpc_connection_init(void)
 140 {
 141         conn_hash = cfs_hash_create("CONN_HASH",
 142                                     HASH_CONN_CUR_BITS,
 143                                     HASH_CONN_MAX_BITS,
 144                                     HASH_CONN_BKT_BITS, 0,
 145                                     CFS_HASH_MIN_THETA,
 146                                     CFS_HASH_MAX_THETA,
 147                                     &conn_hash_ops, CFS_HASH_DEFAULT);
 148         if (!conn_hash)
 149                 return -ENOMEM;
 150
 151         return 0;
 152 }
 153 EXPORT_SYMBOL(ptlrpc_connection_init);
 154
 155 void ptlrpc_connection_fini(void)
 156 {
 157         cfs_hash_putref(conn_hash);
 158 }
 159 EXPORT_SYMBOL(ptlrpc_connection_fini);
 160
 161 /*
 162  * Hash operations for net_peer<->connection
 163  */
 164 static unsigned
 165 conn_hashfn(struct cfs_hash *hs, const void *key, unsigned mask)
 166 {
 167         return cfs_hash_djb2_hash(key, sizeof(lnet_process_id_t), mask);
 168 }
 169
 170 static int
 171 conn_keycmp(const void *key, struct hlist_node *hnode)
 172 {
 173         struct ptlrpc_connection *conn;
 174         const lnet_process_id_t *conn_key;
 175
 176         LASSERT(key);
 177         conn_key = key;
 178         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 179
 180         return conn_key->nid == conn->c_peer.nid &&
 181                conn_key->pid == conn->c_peer.pid;
 182 }
 183
 184 static void *
 185 conn_key(struct hlist_node *hnode)
 186 {
 187         struct ptlrpc_connection *conn;
 188
 189         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 190         return &conn->c_peer;
 191 }
 192
 193 static void *
 194 conn_object(struct hlist_node *hnode)
 195 {
 196         return hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 197 }
 198
 199 static void
 200 conn_get(struct cfs_hash *hs, struct hlist_node *hnode)
 201 {
 202         struct ptlrpc_connection *conn;
 203
 204         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 205         atomic_inc(&conn->c_refcount);
 206 }
 207
 208 static void
 209 conn_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
 210 {
 211         struct ptlrpc_connection *conn;
 212
 213         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 214         atomic_dec(&conn->c_refcount);
 215 }
 216
 217 static void
 218 conn_exit(struct cfs_hash *hs, struct hlist_node *hnode)
 219 {
 220         struct ptlrpc_connection *conn;
 221
 222         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 223         /*
 224          * Nothing should be left. Connection user put it and
 225          * connection also was deleted from table by this time
 226          * so we should have 0 refs.
 227          */
 228         LASSERTF(atomic_read(&conn->c_refcount) == 0,
 229                  "Busy connection with %d refs\n",
 230                  atomic_read(&conn->c_refcount));
 231         kfree(conn);
 232 }
 233
 234 static struct cfs_hash_ops conn_hash_ops = {
 235         .hs_hash        = conn_hashfn,
 236         .hs_keycmp      = conn_keycmp,
 237         .hs_key         = conn_key,
 238         .hs_object      = conn_object,
 239         .hs_get         = conn_get,
 240         .hs_put_locked  = conn_put_locked,
 241         .hs_exit        = conn_exit,
 242 };