1/* $NetBSD: dmover_backend.c,v 1.8 2008/01/05 02:47:03 matt 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 1.8 2008/01/05 02:47:03 matt Exp $"); 44 45#include <sys/param.h> 46#include <sys/mutex.h> 47#include <sys/systm.h> 48#include <sys/once.h> 49 50#include <dev/dmover/dmovervar.h> 51 52TAILQ_HEAD(, dmover_backend) dmover_backend_list; 53kmutex_t dmover_backend_list_lock; 54static bool initialized; 55 56static int 57initialize(void) 58{ 59 60 KASSERT(initialized == false); 61 62 TAILQ_INIT(&dmover_backend_list); 63 mutex_init(&dmover_backend_list_lock, MUTEX_DEFAULT, IPL_VM); 64 65 /* Initialize the other bits of dmover. */ 66 dmover_session_initialize(); 67 dmover_request_initialize(); 68 dmover_process_initialize(); 69 70 initialized = true; 71 72 return 0; 73} 74 75/* 76 * dmover_backend_register: [back-end interface function] 77 * 78 * Register a back-end with dmover-api. 79 */ 80void 81dmover_backend_register(struct dmover_backend *dmb) 82{ 83 static ONCE_DECL(control); 84 85 RUN_ONCE(&control, initialize); 86 87 KASSERT(initialized == true); 88 89 LIST_INIT(&dmb->dmb_sessions); 90 dmb->dmb_nsessions = 0; 91 92 TAILQ_INIT(&dmb->dmb_pendreqs); 93 dmb->dmb_npendreqs = 0; 94 95 mutex_enter(&dmover_backend_list_lock); 96 TAILQ_INSERT_TAIL(&dmover_backend_list, dmb, dmb_list); 97 mutex_exit(&dmover_backend_list_lock); 98} 99 100/* 101 * dmover_backend_unregister: [back-end interface function] 102 * 103 * Un-register a back-end from dmover-api. 104 */ 105void 106dmover_backend_unregister(struct dmover_backend *dmb) 107{ 108 109 KASSERT(initialized == true); 110 111 /* XXX */ 112 if (dmb->dmb_nsessions) 113 panic("dmover_backend_unregister"); 114 115 mutex_enter(&dmover_backend_list_lock); 116 TAILQ_REMOVE(&dmover_backend_list, dmb, dmb_list); 117 mutex_exit(&dmover_backend_list_lock); 118} 119 120/* 121 * dmover_backend_alloc: 122 * 123 * Allocate and return a back-end on behalf of a session. 124 */ 125int 126dmover_backend_alloc(struct dmover_session *dses, const char *type) 127{ 128 struct dmover_backend *dmb, *best_dmb = NULL; 129 const struct dmover_algdesc *algdesc, *best_algdesc = NULL; 130 131 if (__predict_false(initialized == false)) { 132 return (ESRCH); 133 } 134 135 mutex_enter(&dmover_backend_list_lock); 136 137 /* First, find a back-end that can handle the session parts. */ 138 for (dmb = TAILQ_FIRST(&dmover_backend_list); dmb != NULL; 139 dmb = TAILQ_NEXT(dmb, dmb_list)) { 140 /* 141 * First, check to see if the back-end supports the 142 * function we wish to perform. 143 */ 144 algdesc = dmover_algdesc_lookup(dmb->dmb_algdescs, 145 dmb->dmb_nalgdescs, type); 146 if (algdesc == NULL) 147 continue; 148 149 if (best_dmb == NULL) { 150 best_dmb = dmb; 151 best_algdesc = algdesc; 152 continue; 153 } 154 155 /* 156 * XXX All the stuff from here on should be shot in 157 * XXX the head. Instead, we should build a list 158 * XXX of candidates, and select the best back-end 159 * XXX when a request is scheduled for processing. 160 */ 161 162 if (dmb->dmb_speed >= best_dmb->dmb_speed) { 163 /* 164 * If the current best match is slower than 165 * this back-end, then this one is the new 166 * best match. 167 */ 168 if (dmb->dmb_speed > best_dmb->dmb_speed) { 169 best_dmb = dmb; 170 best_algdesc = algdesc; 171 continue; 172 } 173 174 /* 175 * If this back-end has fewer sessions allocated 176 * to it than the current best match, then this 177 * one is now the best match. 178 */ 179 if (best_dmb->dmb_nsessions > dmb->dmb_nsessions) { 180 best_dmb = dmb; 181 best_algdesc = algdesc; 182 continue; 183 } 184 } 185 } 186 if (best_dmb == NULL) { 187 mutex_exit(&dmover_backend_list_lock); 188 return (ESRCH); 189 } 190 191 KASSERT(best_algdesc != NULL); 192 193 /* Plug the back-end into the static (XXX) assignment. */ 194 dses->__dses_assignment.das_backend = best_dmb; 195 dses->__dses_assignment.das_algdesc = best_algdesc; 196 197 dses->dses_ninputs = best_algdesc->dad_ninputs; 198 199 LIST_INSERT_HEAD(&best_dmb->dmb_sessions, dses, __dses_list); 200 best_dmb->dmb_nsessions++; 201 202 mutex_exit(&dmover_backend_list_lock); 203 204 return (0); 205} 206 207/* 208 * dmover_backend_release: 209 * 210 * Release the back-end from the specified session. 211 */ 212void 213dmover_backend_release(struct dmover_session *dses) 214{ 215 struct dmover_backend *dmb; 216 217 mutex_enter(&dmover_backend_list_lock); 218 219 /* XXX Clear out the static assignment. */ 220 dmb = dses->__dses_assignment.das_backend; 221 dses->__dses_assignment.das_backend = NULL; 222 dses->__dses_assignment.das_algdesc = NULL; 223 224 LIST_REMOVE(dses, __dses_list); 225 dmb->dmb_nsessions--; 226 227 mutex_exit(&dmover_backend_list_lock); 228} 229