/* $NetBSD: kern_rwlock_obj.c,v 1.2 2010/03/31 19:59:39 ad Exp $ */ /*- * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Andrew Doran. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``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 THE FOUNDATION OR CONTRIBUTORS * 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. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_rwlock_obj.c,v 1.2 2010/03/31 19:59:39 ad Exp $"); #include #include #include #include /* Mutex cache */ #define RW_OBJ_MAGIC 0x85d3c85d struct krwobj { krwlock_t ro_lock; u_int ro_magic; u_int ro_refcnt; }; static int rw_obj_ctor(void *, void *, int); static pool_cache_t rw_obj_cache; /* * rw_obj_init: * * Initialize the rw object store. */ void rw_obj_init(void) { rw_obj_cache = pool_cache_init(sizeof(struct krwobj), coherency_unit, 0, 0, "rwlock", NULL, IPL_NONE, rw_obj_ctor, NULL, NULL); } /* * rw_obj_ctor: * * Initialize a new lock for the cache. */ static int rw_obj_ctor(void *arg, void *obj, int flags) { struct krwobj * ro = obj; ro->ro_magic = RW_OBJ_MAGIC; return 0; } /* * rw_obj_alloc: * * Allocate a single lock object. */ krwlock_t * rw_obj_alloc(void) { struct krwobj *ro; ro = pool_cache_get(rw_obj_cache, PR_WAITOK); rw_init(&ro->ro_lock); ro->ro_refcnt = 1; return (krwlock_t *)ro; } /* * rw_obj_hold: * * Add a single reference to a lock object. A reference to the object * must already be held, and must be held across this call. */ void rw_obj_hold(krwlock_t *lock) { struct krwobj *ro = (struct krwobj *)lock; KASSERT(ro->ro_magic == RW_OBJ_MAGIC); KASSERT(ro->ro_refcnt > 0); atomic_inc_uint(&ro->ro_refcnt); } /* * rw_obj_free: * * Drop a reference from a lock object. If the last reference is being * dropped, free the object and return true. Otherwise, return false. */ bool rw_obj_free(krwlock_t *lock) { struct krwobj *ro = (struct krwobj *)lock; KASSERT(ro->ro_magic == RW_OBJ_MAGIC); KASSERT(ro->ro_refcnt > 0); if (atomic_dec_uint_nv(&ro->ro_refcnt) > 0) { return false; } rw_destroy(&ro->ro_lock); pool_cache_put(rw_obj_cache, ro); return true; }