FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_specificdata.c

     /*      $NetBSD: subr_specificdata.c,v 1.7 2006/11/01 10:17:59 yamt Exp $       */
     
     /*-
      * Copyright (c) 2006 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe.
      *
     * 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 by the NetBSD
     *      Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * 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.
     */
    
    /*-
     * Copyright (c) 2006 YAMAMOTO Takashi.
     * All rights reserved.
     *
     * 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 AUTHOR 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 AUTHOR 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 <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: subr_specificdata.c,v 1.7 2006/11/01 10:17:59 yamt Exp $");
    
    #include <sys/param.h>
    #include <sys/kmem.h>
    #include <sys/proc.h>
    #include <sys/specificdata.h>
    #include <sys/queue.h>
    
    /*
     * Locking notes:
     *
     * The specdataref_container pointer in the specificdata_reference
     * is volatile.  To read it, you must hold EITHER the domain lock
     * or the ref lock.  To write it, you must hold BOTH the domain lock
     * and the ref lock.  The locks must be acquired in the following
     * order:
     *      domain -> ref
     */
    
    typedef struct {
            specificdata_dtor_t     ski_dtor;
    } specificdata_key_impl;
    
    struct specificdata_container {
            size_t          sc_nkey;
            LIST_ENTRY(specificdata_container) sc_list;
            void *          sc_data[];      /* variable length */
    };
    
    #define SPECIFICDATA_CONTAINER_BYTESIZE(n)              \
            (sizeof(struct specificdata_container) + ((n) * sizeof(void *)))
    
    struct specificdata_domain {
            struct lock     sd_lock;
           unsigned int    sd_nkey;
           LIST_HEAD(, specificdata_container) sd_list;
           specificdata_key_impl *sd_keys;
   };
   
   #define specdataref_lock_init(ref)                      \
                                   simple_lock_init(&(ref)->specdataref_slock)
   #define specdataref_lock(ref)   simple_lock(&(ref)->specdataref_slock)
   #define specdataref_unlock(ref) simple_unlock(&(ref)->specdataref_slock)
   
   static void
   specificdata_domain_lock(specificdata_domain_t sd)
   {
   
           ASSERT_SLEEPABLE(NULL, __func__);
           lockmgr(&sd->sd_lock, LK_EXCLUSIVE, 0);
   }
   
   static void
   specificdata_domain_unlock(specificdata_domain_t sd)
   {
   
           lockmgr(&sd->sd_lock, LK_RELEASE, 0);
   }
   
   static void
   specificdata_container_link(specificdata_domain_t sd,
                               specificdata_container_t sc)
   {
   
           LIST_INSERT_HEAD(&sd->sd_list, sc, sc_list);
   }
   
   static void
   specificdata_container_unlink(specificdata_domain_t sd,
                                 specificdata_container_t sc)
   {
   
           LIST_REMOVE(sc, sc_list);
   }
   
   static void
   specificdata_destroy_datum(specificdata_domain_t sd,
                              specificdata_container_t sc, specificdata_key_t key)
   {
           specificdata_dtor_t dtor;
           void *data;
   
           if (key >= sc->sc_nkey)
                   return;
   
           KASSERT(key < sd->sd_nkey);
           
           data = sc->sc_data[key];
           dtor = sd->sd_keys[key].ski_dtor;
   
           if (dtor != NULL) {
                   if (data != NULL) {
                           sc->sc_data[key] = NULL;
                           (*dtor)(data);
                   }
           } else {
                   KASSERT(data == NULL);
           }
   }
   
   static void
   specificdata_noop_dtor(void *data)
   {
   
           /* nothing */
   }
   
   /*
    * specificdata_domain_create --
    *      Create a specifidata domain.
    */
   specificdata_domain_t
   specificdata_domain_create(void)
   {
           specificdata_domain_t sd;
   
           sd = kmem_zalloc(sizeof(*sd), KM_SLEEP);
           KASSERT(sd != NULL);
           lockinit(&sd->sd_lock, PLOCK, "specdata", 0, 0);
           LIST_INIT(&sd->sd_list);
   
           return (sd);
   }
   
   /*
    * specificdata_domain_delete --
    *      Destroy a specifidata domain.
    */
   void
   specificdata_domain_delete(specificdata_domain_t sd)
   {
   
           panic("specificdata_domain_delete: not implemented");
   }
   
   /*
    * specificdata_key_create --
    *      Create a specificdata key for a domain.
    *
    *      Note: This is a rare operation.
    */
   int
   specificdata_key_create(specificdata_domain_t sd, specificdata_key_t *keyp,
                           specificdata_dtor_t dtor)
   {
           specificdata_key_impl *newkeys;
           specificdata_key_t key = 0;
           size_t nsz;
   
           ASSERT_SLEEPABLE(NULL, __func__);
   
           if (dtor == NULL)
                   dtor = specificdata_noop_dtor;
           
           specificdata_domain_lock(sd);
   
           if (sd->sd_keys == NULL)
                   goto needalloc;
   
           for (; key < sd->sd_nkey; key++) {
                   if (sd->sd_keys[key].ski_dtor == NULL)
                           goto gotit;
           }
   
    needalloc:
           nsz = (sd->sd_nkey + 1) * sizeof(*newkeys);
           newkeys = kmem_zalloc(nsz, KM_SLEEP);
           KASSERT(newkeys != NULL);
           if (sd->sd_keys != NULL) {
                   size_t osz = sd->sd_nkey * sizeof(*newkeys);
                   memcpy(newkeys, sd->sd_keys, osz);
                   kmem_free(sd->sd_keys, osz);
           }
           sd->sd_keys = newkeys;
           sd->sd_nkey++;
    gotit:
           sd->sd_keys[key].ski_dtor = dtor;
   
           specificdata_domain_unlock(sd);
   
           *keyp = key;
           return (0);
   }
   
   /*
    * specificdata_key_delete --
    *      Destroy a specificdata key for a domain.
    *
    *      Note: This is a rare operation.
    */
   void
   specificdata_key_delete(specificdata_domain_t sd, specificdata_key_t key)
   {
           specificdata_container_t sc;
   
           specificdata_domain_lock(sd);
   
           if (key >= sd->sd_nkey)
                   goto out;
   
           /*
            * Traverse all of the specificdata containers in the domain
            * and the destroy the datum for the dying key.
            */
           LIST_FOREACH(sc, &sd->sd_list, sc_list) {
                   specificdata_destroy_datum(sd, sc, key);
           }
   
           sd->sd_keys[key].ski_dtor = NULL;
   
    out:
           specificdata_domain_unlock(sd);
   }
   
   /*
    * specificdata_init --
    *      Initialize a specificdata container for operation in the
    *      specified domain.
    */
   int
   specificdata_init(specificdata_domain_t sd, specificdata_reference *ref)
   {
   
           /*
            * Just NULL-out the container pointer; we'll allocate the
            * container the first time specificdata is put into it.
            */
           ref->specdataref_container = NULL;
           specdataref_lock_init(ref);
   
           return (0);
   }
   
   /*
    * specificdata_fini --
    *      Destroy a specificdata container.  We destroy all of the datums
    *      stuffed into the container just as if the key were destroyed.
    */
   void
   specificdata_fini(specificdata_domain_t sd, specificdata_reference *ref)
   {
           specificdata_container_t sc;
           specificdata_key_t key;
   
           ASSERT_SLEEPABLE(NULL, __func__);
   
           sc = ref->specdataref_container;
           if (sc == NULL)
                   return;
           ref->specdataref_container = NULL;
           
           specificdata_domain_lock(sd);
   
           specificdata_container_unlink(sd, sc);
           for (key = 0; key < sc->sc_nkey; key++) {
                   specificdata_destroy_datum(sd, sc, key);
           }
   
           specificdata_domain_unlock(sd);
   
           kmem_free(sc, SPECIFICDATA_CONTAINER_BYTESIZE(sc->sc_nkey));
   }
   
   /*
    * specificdata_getspecific --
    *      Get a datum from a container.
    *
    *      Note: This routine is guaranteed not to sleep.
    */
   void *
   specificdata_getspecific(specificdata_domain_t sd, specificdata_reference *ref,
                            specificdata_key_t key)
   {
           specificdata_container_t sc;
           void *data = NULL;
   
           specdataref_lock(ref);
   
           sc = ref->specdataref_container;
           if (sc != NULL && key < sc->sc_nkey)
                   data = sc->sc_data[key];
   
           specdataref_unlock(ref);
   
           return (data);
   }
   
   /*
    * specificdata_getspecific_unlocked --
    *      Get a datum from a container in a lockless fashion.
    *
    *      Note: When using this routine, care must be taken to ensure
    *      that no other thread could cause the specificdata_reference
    *      to become invalid (i.e. point at the wrong container) by
    *      issuing a setspecific call or destroying the container.
    *
    *      Note #2: This routine is guaranteed not to sleep.
    */
   void *
   specificdata_getspecific_unlocked(specificdata_domain_t sd,
                                     specificdata_reference *ref,
                                     specificdata_key_t key)
   {
           specificdata_container_t sc;
           
           sc = ref->specdataref_container;
           if (sc != NULL && key < sc->sc_nkey)
                   return (sc->sc_data[key]);
   
           return (NULL);
   }
   
   /*
    * specificdata_setspecific --
    *      Put a datum into a container.
    */
   void
   specificdata_setspecific(specificdata_domain_t sd,
                            specificdata_reference *ref,
                            specificdata_key_t key, void *data)
   {
           specificdata_container_t sc, newsc;
           size_t newnkey, sz;
   
           ASSERT_SLEEPABLE(NULL, __func__);
   
           specdataref_lock(ref);
   
           sc = ref->specdataref_container;
           if (__predict_true(sc != NULL && key < sc->sc_nkey)) {
                   sc->sc_data[key] = data;
                   specdataref_unlock(ref);
                   return;
           }
   
           specdataref_unlock(ref);
   
           /*
            * Slow path: need to resize.
            */
           
           specificdata_domain_lock(sd);
           newnkey = sd->sd_nkey;
           if (key >= newnkey) {
                   specificdata_domain_unlock(sd);
                   panic("specificdata_setspecific");
           }
           sz = SPECIFICDATA_CONTAINER_BYTESIZE(newnkey);
           newsc = kmem_zalloc(sz, KM_SLEEP);
           KASSERT(newsc != NULL);
           newsc->sc_nkey = newnkey;
   
           specdataref_lock(ref);
   
           sc = ref->specdataref_container;
           if (sc != NULL) {
                   if (key < sc->sc_nkey) {
                           /*
                            * Someone beat us to the punch.  Unwind and put
                            * the object into the now large enough container.
                            */
                           sc->sc_data[key] = data;
                           specdataref_unlock(ref);
                           specificdata_domain_unlock(sd);
                           kmem_free(newsc, sz);
                           return;
                   }
                   specificdata_container_unlink(sd, sc);
                   memcpy(newsc->sc_data, sc->sc_data,
                          sc->sc_nkey * sizeof(void *));
           }
           newsc->sc_data[key] = data;
           specificdata_container_link(sd, newsc);
           ref->specdataref_container = newsc;
   
           specdataref_unlock(ref);
           specificdata_domain_unlock(sd);
   
           if (sc != NULL)
                   kmem_free(sc, SPECIFICDATA_CONTAINER_BYTESIZE(sc->sc_nkey));
   }

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