NetBSD-5.0.2/sys/dev/dmover/dmover_backend.c
/* $NetBSD: dmover_backend.c,v 1.8 2008/01/05 02:47:03 matt 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 1.8 2008/01/05 02:47:03 matt Exp $");
#include <sys/param.h>
#include <sys/mutex.h>
#include <sys/simplelock.h>
#include <sys/systm.h>
#include <dev/dmover/dmovervar.h>
TAILQ_HEAD(, dmover_backend) dmover_backend_list;
kmutex_t dmover_backend_list_lock;
static int initialized;
static struct simplelock initialized_slock = SIMPLELOCK_INITIALIZER;
static void
initialize(void)
{
simple_lock(&initialized_slock);
if (__predict_true(initialized == 0)) {
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 = 1;
}
simple_unlock(&initialized_slock);
}
/*
* dmover_backend_register: [back-end interface function]
*
* Register a back-end with dmover-api.
*/
void
dmover_backend_register(struct dmover_backend *dmb)
{
if (__predict_false(initialized == 0))
initialize();
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)
{
#ifdef DIAGNOSTIC
if (__predict_false(initialized == 0)) {
int croak;
simple_lock(&initialized_slock);
croak = (initialized == 0);
simple_unlock(&initialized_slock);
if (croak)
panic("dmover_backend_unregister: not initialized");
}
#endif
/* 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 == 0)) {
int fail;
simple_lock(&initialized_slock);
fail = (initialized == 0);
simple_unlock(&initialized_slock);
if (fail)
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);
}