/* $NetBSD: dmover_backend.c,v 1.9 2011/05/14 18:24:47 jakllsch Exp $ */ /* * Copyright (c) 2002 Wasabi Systems, Inc. * All rights reserved. * * Written by Jason R. Thorpe for Wasabi Systems, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed for the NetBSD Project by * Wasabi Systems, Inc. * 4. The name of Wasabi Systems, Inc. may not be used to endorse * or promote products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * dmover_backend.c: Backend management functions for dmover-api. */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: dmover_backend.c,v 1.9 2011/05/14 18:24:47 jakllsch Exp $"); #include <sys/param.h> #include <sys/mutex.h> #include <sys/systm.h> #include <sys/once.h> #include <dev/dmover/dmovervar.h> TAILQ_HEAD(, dmover_backend) dmover_backend_list; kmutex_t dmover_backend_list_lock; static bool initialized; static int initialize(void) { KASSERT(initialized == false); TAILQ_INIT(&dmover_backend_list); mutex_init(&dmover_backend_list_lock, MUTEX_DEFAULT, IPL_VM); /* Initialize the other bits of dmover. */ dmover_session_initialize(); dmover_request_initialize(); dmover_process_initialize(); initialized = true; return 0; } /* * dmover_backend_register: [back-end interface function] * * Register a back-end with dmover-api. */ void dmover_backend_register(struct dmover_backend *dmb) { static ONCE_DECL(control); RUN_ONCE(&control, initialize); KASSERT(initialized == true); LIST_INIT(&dmb->dmb_sessions); dmb->dmb_nsessions = 0; TAILQ_INIT(&dmb->dmb_pendreqs); dmb->dmb_npendreqs = 0; mutex_enter(&dmover_backend_list_lock); TAILQ_INSERT_TAIL(&dmover_backend_list, dmb, dmb_list); mutex_exit(&dmover_backend_list_lock); } /* * dmover_backend_unregister: [back-end interface function] * * Un-register a back-end from dmover-api. */ void dmover_backend_unregister(struct dmover_backend *dmb) { KASSERT(initialized == true); /* XXX */ if (dmb->dmb_nsessions) panic("dmover_backend_unregister"); mutex_enter(&dmover_backend_list_lock); TAILQ_REMOVE(&dmover_backend_list, dmb, dmb_list); mutex_exit(&dmover_backend_list_lock); } /* * dmover_backend_alloc: * * Allocate and return a back-end on behalf of a session. */ int dmover_backend_alloc(struct dmover_session *dses, const char *type) { struct dmover_backend *dmb, *best_dmb = NULL; const struct dmover_algdesc *algdesc, *best_algdesc = NULL; if (__predict_false(initialized == false)) { return (ESRCH); } mutex_enter(&dmover_backend_list_lock); /* First, find a back-end that can handle the session parts. */ for (dmb = TAILQ_FIRST(&dmover_backend_list); dmb != NULL; dmb = TAILQ_NEXT(dmb, dmb_list)) { /* * First, check to see if the back-end supports the * function we wish to perform. */ algdesc = dmover_algdesc_lookup(dmb->dmb_algdescs, dmb->dmb_nalgdescs, type); if (algdesc == NULL) continue; if (best_dmb == NULL) { best_dmb = dmb; best_algdesc = algdesc; continue; } /* * XXX All the stuff from here on should be shot in * XXX the head. Instead, we should build a list * XXX of candidates, and select the best back-end * XXX when a request is scheduled for processing. */ if (dmb->dmb_speed >= best_dmb->dmb_speed) { /* * If the current best match is slower than * this back-end, then this one is the new * best match. */ if (dmb->dmb_speed > best_dmb->dmb_speed) { best_dmb = dmb; best_algdesc = algdesc; continue; } /* * If this back-end has fewer sessions allocated * to it than the current best match, then this * one is now the best match. */ if (best_dmb->dmb_nsessions > dmb->dmb_nsessions) { best_dmb = dmb; best_algdesc = algdesc; continue; } } } if (best_dmb == NULL) { mutex_exit(&dmover_backend_list_lock); return (ESRCH); } KASSERT(best_algdesc != NULL); /* Plug the back-end into the static (XXX) assignment. */ dses->__dses_assignment.das_backend = best_dmb; dses->__dses_assignment.das_algdesc = best_algdesc; dses->dses_ninputs = best_algdesc->dad_ninputs; LIST_INSERT_HEAD(&best_dmb->dmb_sessions, dses, __dses_list); best_dmb->dmb_nsessions++; mutex_exit(&dmover_backend_list_lock); return (0); } /* * dmover_backend_release: * * Release the back-end from the specified session. */ void dmover_backend_release(struct dmover_session *dses) { struct dmover_backend *dmb; mutex_enter(&dmover_backend_list_lock); /* XXX Clear out the static assignment. */ dmb = dses->__dses_assignment.das_backend; dses->__dses_assignment.das_backend = NULL; dses->__dses_assignment.das_algdesc = NULL; LIST_REMOVE(dses, __dses_list); dmb->dmb_nsessions--; mutex_exit(&dmover_backend_list_lock); }
