1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 23 /* 24 * Copyright 2005 Sun Microsystems, Inc. All rights reserved. 25 * Use is subject to license terms. 26 */ 27 28 /* 29 * This file contains functions that enables the rpc library to synchronize 30 * between various threads while they compete for a particular file descriptor. 31 */ 32 33 #include "mt.h" 34 #include "rpc_mt.h" 35 #include <rpc/rpc.h> 36 #include <errno.h> 37 #include <sys/poll.h> 38 #include <syslog.h> 39 #include <sys/types.h> 40 #include <stdlib.h> 41 #include <unistd.h> 42 43 /* 44 * A block holds an array of maxBlockSize cell and associated recursive locks 45 */ 46 47 #define CELLTBLSZ 1024 48 49 typedef struct rpcfd_block { 50 struct rpcfd_block *next; /* Next Block */ 51 struct rpcfd_block *prev; /* prev Block */ 52 int end; /* fd of last lock in the list */ 53 mutex_t lock[CELLTBLSZ]; /* recursive locks */ 54 } rpcfd_block_t; 55 56 mutex_t rpc_fd_list_lock = DEFAULTMUTEX; /* protects list manipulation */ 57 58 /* Following functions create and manipulates the dgfd lock object */ 59 60 static mutex_t *search(const void *handle, int fd); 61 static rpcfd_block_t *create_block(const void *handle, int fd); 62 63 void * 64 rpc_fd_init(void) 65 { 66 /* 67 * Create first chunk of CELLTBLSZ 68 * (No lock is required for initial creation.) 69 */ 70 return (create_block(NULL, 0)); 71 } 72 73 /* 74 * If rpc_fd_lock() fails to acquire a lock, it returns non-zero (ENOMEM). 75 * (The operation can only fail due to a malloc() failure.) 76 * The caller of rpc_fd_lock() must call rpc_fd_unlock() even if 77 * rpc_fd_lock() failed. This keeps _sigoff() and _sigon() balanced. 78 * 79 * If search() and create_block() fail for rpc_fd_lock(), then search() 80 * will fail for rpc_fd_unlock(), so mutex_lock() and mutex_unlock() 81 * calls will be balanced. In any case, since the mutex is marked 82 * LOCK_ERRORCHECK, an additional mutex_unlock() does nothing. 83 */ 84 int 85 rpc_fd_lock(const void *handle, int fd) 86 { 87 mutex_t *mp; 88 rpcfd_block_t *p; 89 90 _sigoff(); 91 (void) mutex_lock(&rpc_fd_list_lock); 92 mp = search(handle, fd); 93 if (mp == NULL) { 94 p = create_block(handle, fd); 95 if (p != NULL) 96 mp = &p->lock[fd % CELLTBLSZ]; 97 } 98 (void) mutex_unlock(&rpc_fd_list_lock); 99 if (mp == NULL) 100 return (ENOMEM); 101 (void) mutex_lock(mp); 102 return (0); 103 } 104 105 void 106 rpc_fd_unlock(const void *handle, int fd) 107 { 108 mutex_t *mp; 109 110 (void) mutex_lock(&rpc_fd_list_lock); 111 mp = search(handle, fd); 112 (void) mutex_unlock(&rpc_fd_list_lock); 113 if (mp != NULL) 114 (void) mutex_unlock(mp); 115 _sigon(); 116 } 117 118 static rpcfd_block_t * 119 create_block(const void *handle, int fd) 120 { 121 rpcfd_block_t *l, *lprev; 122 rpcfd_block_t *p; 123 int i; 124 125 p = malloc(sizeof (rpcfd_block_t)); 126 if (p == NULL) 127 return (NULL); 128 129 for (i = 0; i < CELLTBLSZ; i++) { 130 (void) mutex_init(&p->lock[i], 131 USYNC_THREAD | LOCK_RECURSIVE | LOCK_ERRORCHECK, NULL); 132 } 133 p->end = (((fd + CELLTBLSZ) / CELLTBLSZ) * CELLTBLSZ) - 1; 134 lprev = NULL; 135 for (l = (rpcfd_block_t *)handle; l; l = l->next) { 136 lprev = l; 137 if (fd < l->end) 138 break; 139 } 140 141 p->next = l; 142 p->prev = lprev; 143 if (lprev) 144 lprev->next = p; 145 if (l) 146 l->prev = p; 147 148 return (p); 149 } 150 151 /* 152 * Called with rpc_fd_list_lock held. 153 */ 154 static mutex_t * 155 search(const void *handle, int fd) 156 { 157 rpcfd_block_t *p; 158 159 for (p = (rpcfd_block_t *)handle; p; p = p->next) { 160 if (fd <= p->end) 161 return (&p->lock[fd % CELLTBLSZ]); 162 } 163 164 return (NULL); 165 } 166