root/trunk/umem_fork.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Portions Copyright 2006 OmniTI, Inc.
 */

/* #pragma ident        "@(#)umem_fork.c        1.3     05/06/08 SMI" */

#include "config.h"
/* #include "mtlib.h" */
#include "umem_base.h"
#include "vmem_base.h"

#ifndef _WIN32
#include <unistd.h>

/*
 * The following functions are for pre- and post-fork1(2) handling.
 */

static void
umem_lockup_cache(umem_cache_t *cp)
{
        int idx;
        int ncpus = cp->cache_cpu_mask + 1;

        for (idx = 0; idx < ncpus; idx++)
                (void) mutex_lock(&cp->cache_cpu[idx].cc_lock);

        (void) mutex_lock(&cp->cache_depot_lock);
        (void) mutex_lock(&cp->cache_lock);
}

static void
umem_release_cache(umem_cache_t *cp)
{
        int idx;
        int ncpus = cp->cache_cpu_mask + 1;

        (void) mutex_unlock(&cp->cache_lock);
        (void) mutex_unlock(&cp->cache_depot_lock);

        for (idx = 0; idx < ncpus; idx++)
                (void) mutex_unlock(&cp->cache_cpu[idx].cc_lock);
}

static void
umem_lockup_log_header(umem_log_header_t *lhp)
{
        int idx;
        if (lhp == NULL)
                return;
        for (idx = 0; idx < umem_max_ncpus; idx++)
                (void) mutex_lock(&lhp->lh_cpu[idx].clh_lock);

        (void) mutex_lock(&lhp->lh_lock);
}

static void
umem_release_log_header(umem_log_header_t *lhp)
{
        int idx;
        if (lhp == NULL)
                return;

        (void) mutex_unlock(&lhp->lh_lock);

        for (idx = 0; idx < umem_max_ncpus; idx++)
                (void) mutex_unlock(&lhp->lh_cpu[idx].clh_lock);
}

static void
umem_lockup(void)
{
        umem_cache_t *cp;

        (void) mutex_lock(&umem_init_lock);
        /*
         * If another thread is busy initializing the library, we must
         * wait for it to complete (by calling umem_init()) before allowing
         * the fork() to proceed.
         */
        if (umem_ready == UMEM_READY_INITING && umem_init_thr != thr_self()) {
                (void) mutex_unlock(&umem_init_lock);
                (void) umem_init();
                (void) mutex_lock(&umem_init_lock);
        }
        (void) mutex_lock(&umem_cache_lock);
        (void) mutex_lock(&umem_update_lock);
        (void) mutex_lock(&umem_flags_lock);

        umem_lockup_cache(&umem_null_cache);
        for (cp = umem_null_cache.cache_prev; cp != &umem_null_cache;
            cp = cp->cache_prev)
                umem_lockup_cache(cp);

        umem_lockup_log_header(umem_transaction_log);
        umem_lockup_log_header(umem_content_log);
        umem_lockup_log_header(umem_failure_log);
        umem_lockup_log_header(umem_slab_log);

        (void) cond_broadcast(&umem_update_cv);

        vmem_sbrk_lockup();
        vmem_lockup();
}

static void
umem_release(void)
{
        umem_cache_t *cp;

        vmem_release();
        vmem_sbrk_release();

        umem_release_log_header(umem_slab_log);
        umem_release_log_header(umem_failure_log);
        umem_release_log_header(umem_content_log);
        umem_release_log_header(umem_transaction_log);

        for (cp = umem_null_cache.cache_next; cp != &umem_null_cache;
            cp = cp->cache_next)
                umem_release_cache(cp);
        umem_release_cache(&umem_null_cache);

        (void) mutex_unlock(&umem_flags_lock);
        (void) mutex_unlock(&umem_update_lock);
        (void) mutex_unlock(&umem_cache_lock);
        (void) mutex_unlock(&umem_init_lock);
}

static void
umem_release_child(void)
{
        umem_cache_t *cp;

        /*
         * Clean up the update state
         */
        umem_update_thr = 0;

        if (umem_st_update_thr != thr_self()) {
                umem_st_update_thr = 0;
                umem_reaping = UMEM_REAP_DONE;

                for (cp = umem_null_cache.cache_next; cp != &umem_null_cache;
                    cp = cp->cache_next) {
                        if (cp->cache_uflags & UMU_NOTIFY)
                                cp->cache_uflags &= ~UMU_NOTIFY;

                        /*
                         * If the cache is active, we just re-add it to
                         * the update list.  This will re-do any active
                         * updates on the cache, but that won't break
                         * anything.
                         *
                         * The worst that can happen is a cache has
                         * its magazines rescaled twice, instead of once.
                         */
                        if (cp->cache_uflags & UMU_ACTIVE) {
                                umem_cache_t *cnext, *cprev;

                                ASSERT(cp->cache_unext == NULL &&
                                    cp->cache_uprev == NULL);

                                cp->cache_uflags &= ~UMU_ACTIVE;
                                cp->cache_unext = cnext = &umem_null_cache;
                                cp->cache_uprev = cprev =
                                    umem_null_cache.cache_uprev;
                                cnext->cache_uprev = cp;
                                cprev->cache_unext = cp;
                        }
                }
        }

        umem_release();
}
#endif

void
umem_forkhandler_init(void)
{
#ifndef _WIN32
        /*
         * There is no way to unregister these atfork functions,
         * but we don't need to.  The dynamic linker and libc take
         * care of unregistering them if/when the library is unloaded.
         */
        (void) pthread_atfork(umem_lockup, umem_release, umem_release_child);
#endif
}