dmover_backend.c revision 1.6
1 /* $NetBSD: dmover_backend.c,v 1.6 2007/07/09 21:00:32 ad Exp $ */ 2 3 /* 4 * Copyright (c) 2002 Wasabi Systems, Inc. 5 * All rights reserved. 6 * 7 * Written by Jason R. Thorpe for Wasabi Systems, Inc. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed for the NetBSD Project by 20 * Wasabi Systems, Inc. 21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse 22 * or promote products derived from this software without specific prior 23 * written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC 29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 * POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 /* 39 * dmover_backend.c: Backend management functions for dmover-api. 40 */ 41 42 #include <sys/cdefs.h> 43 __KERNEL_RCSID(0, "$NetBSD: dmover_backend.c,v 1.6 2007/07/09 21:00:32 ad Exp $"); 44 45 #include <sys/param.h> 46 #include <sys/mutex.h> 47 #include <sys/systm.h> 48 49 #include <dev/dmover/dmovervar.h> 50 51 TAILQ_HEAD(, dmover_backend) dmover_backend_list; 52 kmutex_t dmover_backend_list_lock; 53 static int initialized; 54 static struct simplelock initialized_slock = SIMPLELOCK_INITIALIZER; 55 56 static void 57 initialize(void) 58 { 59 60 simple_lock(&initialized_slock); 61 if (__predict_true(initialized == 0)) { 62 TAILQ_INIT(&dmover_backend_list); 63 mutex_init(&dmover_backend_list_lock, MUTEX_DRIVER, IPL_BIO); 64 65 /* Initialize the other bits of dmover. */ 66 dmover_session_initialize(); 67 dmover_request_initialize(); 68 dmover_process_initialize(); 69 70 initialized = 1; 71 } 72 simple_unlock(&initialized_slock); 73 } 74 75 /* 76 * dmover_backend_register: [back-end interface function] 77 * 78 * Register a back-end with dmover-api. 79 */ 80 void 81 dmover_backend_register(struct dmover_backend *dmb) 82 { 83 84 if (__predict_false(initialized == 0)) 85 initialize(); 86 87 LIST_INIT(&dmb->dmb_sessions); 88 dmb->dmb_nsessions = 0; 89 90 TAILQ_INIT(&dmb->dmb_pendreqs); 91 dmb->dmb_npendreqs = 0; 92 93 mutex_enter(&dmover_backend_list_lock); 94 TAILQ_INSERT_TAIL(&dmover_backend_list, dmb, dmb_list); 95 mutex_exit(&dmover_backend_list_lock); 96 } 97 98 /* 99 * dmover_backend_unregister: [back-end interface function] 100 * 101 * Un-register a back-end from dmover-api. 102 */ 103 void 104 dmover_backend_unregister(struct dmover_backend *dmb) 105 { 106 107 #ifdef DIAGNOSTIC 108 if (__predict_false(initialized == 0)) { 109 int croak; 110 111 simple_lock(&initialized_slock); 112 croak = (initialized == 0); 113 simple_unlock(&initialized_slock); 114 115 if (croak) 116 panic("dmover_backend_unregister: not initialized"); 117 } 118 #endif 119 120 /* XXX */ 121 if (dmb->dmb_nsessions) 122 panic("dmover_backend_unregister"); 123 124 mutex_enter(&dmover_backend_list_lock); 125 TAILQ_REMOVE(&dmover_backend_list, dmb, dmb_list); 126 mutex_exit(&dmover_backend_list_lock); 127 } 128 129 /* 130 * dmover_backend_alloc: 131 * 132 * Allocate and return a back-end on behalf of a session. 133 */ 134 int 135 dmover_backend_alloc(struct dmover_session *dses, const char *type) 136 { 137 struct dmover_backend *dmb, *best_dmb = NULL; 138 const struct dmover_algdesc *algdesc, *best_algdesc = NULL; 139 140 if (__predict_false(initialized == 0)) { 141 int fail; 142 143 simple_lock(&initialized_slock); 144 fail = (initialized == 0); 145 simple_unlock(&initialized_slock); 146 147 if (fail) 148 return (ESRCH); 149 } 150 151 mutex_enter(&dmover_backend_list_lock); 152 153 /* First, find a back-end that can handle the session parts. */ 154 for (dmb = TAILQ_FIRST(&dmover_backend_list); dmb != NULL; 155 dmb = TAILQ_NEXT(dmb, dmb_list)) { 156 /* 157 * First, check to see if the back-end supports the 158 * function we wish to perform. 159 */ 160 algdesc = dmover_algdesc_lookup(dmb->dmb_algdescs, 161 dmb->dmb_nalgdescs, type); 162 if (algdesc == NULL) 163 continue; 164 165 if (best_dmb == NULL) { 166 best_dmb = dmb; 167 best_algdesc = algdesc; 168 continue; 169 } 170 171 /* 172 * XXX All the stuff from here on should be shot in 173 * XXX the head. Instead, we should build a list 174 * XXX of candidates, and select the best back-end 175 * XXX when a request is scheduled for processing. 176 */ 177 178 if (dmb->dmb_speed >= best_dmb->dmb_speed) { 179 /* 180 * If the current best match is slower than 181 * this back-end, then this one is the new 182 * best match. 183 */ 184 if (dmb->dmb_speed > best_dmb->dmb_speed) { 185 best_dmb = dmb; 186 best_algdesc = algdesc; 187 continue; 188 } 189 190 /* 191 * If this back-end has fewer sessions allocated 192 * to it than the current best match, then this 193 * one is now the best match. 194 */ 195 if (best_dmb->dmb_nsessions > dmb->dmb_nsessions) { 196 best_dmb = dmb; 197 best_algdesc = algdesc; 198 continue; 199 } 200 } 201 } 202 if (best_dmb == NULL) { 203 mutex_exit(&dmover_backend_list_lock); 204 return (ESRCH); 205 } 206 207 KASSERT(best_algdesc != NULL); 208 209 /* Plug the back-end into the static (XXX) assignment. */ 210 dses->__dses_assignment.das_backend = best_dmb; 211 dses->__dses_assignment.das_algdesc = best_algdesc; 212 213 dses->dses_ninputs = best_algdesc->dad_ninputs; 214 215 LIST_INSERT_HEAD(&best_dmb->dmb_sessions, dses, __dses_list); 216 best_dmb->dmb_nsessions++; 217 218 mutex_exit(&dmover_backend_list_lock); 219 220 return (0); 221 } 222 223 /* 224 * dmover_backend_release: 225 * 226 * Release the back-end from the specified session. 227 */ 228 void 229 dmover_backend_release(struct dmover_session *dses) 230 { 231 struct dmover_backend *dmb; 232 233 mutex_enter(&dmover_backend_list_lock); 234 235 /* XXX Clear out the static assignment. */ 236 dmb = dses->__dses_assignment.das_backend; 237 dses->__dses_assignment.das_backend = NULL; 238 dses->__dses_assignment.das_algdesc = NULL; 239 240 LIST_REMOVE(dses, __dses_list); 241 dmb->dmb_nsessions--; 242 243 mutex_exit(&dmover_backend_list_lock); 244 } 245
Indexes created Thu Oct 02 07:10:07 GMT 2025