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 <obd_support.h>
  39 #include <obd_class.h>
  40 #include <lustre_net.h>
  41
  42 #include "ptlrpc_internal.h"
  43
  44 static cfs_hash_t *conn_hash = NULL;
  45 static cfs_hash_ops_t 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         ENTRY;
  53
  54         conn = cfs_hash_lookup(conn_hash, &peer);
  55         if (conn)
  56                 GOTO(out, conn);
  57
  58         OBD_ALLOC_PTR(conn);
  59         if (!conn)
  60                 RETURN(NULL);
  61
  62         conn->c_peer = peer;
  63         conn->c_self = self;
  64         INIT_HLIST_NODE(&conn->c_hash);
  65         atomic_set(&conn->c_refcount, 1);
  66         if (uuid)
  67                 obd_str2uuid(&conn->c_remote_uuid, uuid->uuid);
  68
  69         /*
  70          * Add the newly created conn to the hash, on key collision we
  71          * lost a racing addition and must destroy our newly allocated
  72          * connection.  The object which exists in the has will be
  73          * returned and may be compared against out object.
  74          */
  75         /* In the function below, .hs_keycmp resolves to
  76          * conn_keycmp() */
  77         /* coverity[overrun-buffer-val] */
  78         conn2 = cfs_hash_findadd_unique(conn_hash, &peer, &conn->c_hash);
  79         if (conn != conn2) {
  80                 OBD_FREE_PTR(conn);
  81                 conn = conn2;
  82         }
  83         EXIT;
  84 out:
  85         CDEBUG(D_INFO, "conn=%p refcount %d to %s\n",
  86                conn, atomic_read(&conn->c_refcount),
  87                libcfs_nid2str(conn->c_peer.nid));
  88         return conn;
  89 }
  90 EXPORT_SYMBOL(ptlrpc_connection_get);
  91
  92 int ptlrpc_connection_put(struct ptlrpc_connection *conn)
  93 {
  94         int rc = 0;
  95         ENTRY;
  96
  97         if (!conn)
  98                 RETURN(rc);
  99
 100         LASSERT(atomic_read(&conn->c_refcount) > 1);
 101
 102         /*
 103          * We do not remove connection from hashtable and
 104          * do not free it even if last caller released ref,
 105          * as we want to have it cached for the case it is
 106          * needed again.
 107          *
 108          * Deallocating it and later creating new connection
 109          * again would be wastful. This way we also avoid
 110          * expensive locking to protect things from get/put
 111          * race when found cached connection is freed by
 112          * ptlrpc_connection_put().
 113          *
 114          * It will be freed later in module unload time,
 115          * when ptlrpc_connection_fini()->lh_exit->conn_exit()
 116          * path is called.
 117          */
 118         if (atomic_dec_return(&conn->c_refcount) == 1)
 119                 rc = 1;
 120
 121         CDEBUG(D_INFO, "PUT conn=%p refcount %d to %s\n",
 122                conn, atomic_read(&conn->c_refcount),
 123                libcfs_nid2str(conn->c_peer.nid));
 124
 125         RETURN(rc);
 126 }
 127 EXPORT_SYMBOL(ptlrpc_connection_put);
 128
 129 struct ptlrpc_connection *
 130 ptlrpc_connection_addref(struct ptlrpc_connection *conn)
 131 {
 132         ENTRY;
 133
 134         atomic_inc(&conn->c_refcount);
 135         CDEBUG(D_INFO, "conn=%p refcount %d to %s\n",
 136                conn, atomic_read(&conn->c_refcount),
 137                libcfs_nid2str(conn->c_peer.nid));
 138
 139         RETURN(conn);
 140 }
 141 EXPORT_SYMBOL(ptlrpc_connection_addref);
 142
 143 int ptlrpc_connection_init(void)
 144 {
 145         ENTRY;
 146
 147         conn_hash = cfs_hash_create("CONN_HASH",
 148                                     HASH_CONN_CUR_BITS,
 149                                     HASH_CONN_MAX_BITS,
 150                                     HASH_CONN_BKT_BITS, 0,
 151                                     CFS_HASH_MIN_THETA,
 152                                     CFS_HASH_MAX_THETA,
 153                                     &conn_hash_ops, CFS_HASH_DEFAULT);
 154         if (!conn_hash)
 155                 RETURN(-ENOMEM);
 156
 157         RETURN(0);
 158 }
 159 EXPORT_SYMBOL(ptlrpc_connection_init);
 160
 161 void ptlrpc_connection_fini(void) {
 162         ENTRY;
 163         cfs_hash_putref(conn_hash);
 164         EXIT;
 165 }
 166 EXPORT_SYMBOL(ptlrpc_connection_fini);
 167
 168 /*
 169  * Hash operations for net_peer<->connection
 170  */
 171 static unsigned
 172 conn_hashfn(cfs_hash_t *hs, const void *key, unsigned mask)
 173 {
 174         return cfs_hash_djb2_hash(key, sizeof(lnet_process_id_t), mask);
 175 }
 176
 177 static int
 178 conn_keycmp(const void *key, struct hlist_node *hnode)
 179 {
 180         struct ptlrpc_connection *conn;
 181         const lnet_process_id_t *conn_key;
 182
 183         LASSERT(key != NULL);
 184         conn_key = (lnet_process_id_t*)key;
 185         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 186
 187         return conn_key->nid == conn->c_peer.nid &&
 188                conn_key->pid == conn->c_peer.pid;
 189 }
 190
 191 static void *
 192 conn_key(struct hlist_node *hnode)
 193 {
 194         struct ptlrpc_connection *conn;
 195         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 196         return &conn->c_peer;
 197 }
 198
 199 static void *
 200 conn_object(struct hlist_node *hnode)
 201 {
 202         return hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 203 }
 204
 205 static void
 206 conn_get(cfs_hash_t *hs, struct hlist_node *hnode)
 207 {
 208         struct ptlrpc_connection *conn;
 209
 210         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 211         atomic_inc(&conn->c_refcount);
 212 }
 213
 214 static void
 215 conn_put_locked(cfs_hash_t *hs, struct hlist_node *hnode)
 216 {
 217         struct ptlrpc_connection *conn;
 218
 219         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 220         atomic_dec(&conn->c_refcount);
 221 }
 222
 223 static void
 224 conn_exit(cfs_hash_t *hs, struct hlist_node *hnode)
 225 {
 226         struct ptlrpc_connection *conn;
 227
 228         conn = hlist_entry(hnode, struct ptlrpc_connection, c_hash);
 229         /*
 230          * Nothing should be left. Connection user put it and
 231          * connection also was deleted from table by this time
 232          * so we should have 0 refs.
 233          */
 234         LASSERTF(atomic_read(&conn->c_refcount) == 0,
 235                  "Busy connection with %d refs\n",
 236                  atomic_read(&conn->c_refcount));
 237         OBD_FREE_PTR(conn);
 238 }
 239
 240 static cfs_hash_ops_t conn_hash_ops = {
 241         .hs_hash        = conn_hashfn,
 242         .hs_keycmp      = conn_keycmp,
 243         .hs_key  = conn_key,
 244         .hs_object      = conn_object,
 245         .hs_get  = conn_get,
 246         .hs_put_locked  = conn_put_locked,
 247         .hs_exit        = conn_exit,
 248 };