/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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
 *
 */

static int
dtrace_unload(void)
{
        dtrace_state_t *state;
        int error = 0;

        destroy_dev(dtrace_dev);
        destroy_dev(helper_dev);

        mutex_enter(&dtrace_provider_lock);
        mutex_enter(&dtrace_lock);
        mutex_enter(&cpu_lock);

        ASSERT(dtrace_opens == 0);

        if (dtrace_helpers > 0) {
                mutex_exit(&cpu_lock);
                mutex_exit(&dtrace_lock);
                mutex_exit(&dtrace_provider_lock);
                return (EBUSY);
        }

        if (dtrace_unregister((dtrace_provider_id_t)dtrace_provider) != 0) {
                mutex_exit(&cpu_lock);
                mutex_exit(&dtrace_lock);
                mutex_exit(&dtrace_provider_lock);
                return (EBUSY);
        }

        dtrace_provider = NULL;
        EVENTHANDLER_DEREGISTER(kld_load, dtrace_kld_load_tag);
        EVENTHANDLER_DEREGISTER(kld_unload_try, dtrace_kld_unload_try_tag);

        if ((state = dtrace_anon_grab()) != NULL) {
                /*
                 * If there were ECBs on this state, the provider should
                 * have not been allowed to detach; assert that there is
                 * none.
                 */
                ASSERT(state->dts_necbs == 0);
                dtrace_state_destroy(state);
        }

        bzero(&dtrace_anon, sizeof (dtrace_anon_t));

        mutex_exit(&cpu_lock);

        if (dtrace_probes != NULL) {
                kmem_free(dtrace_probes, 0);
                dtrace_probes = NULL;
                dtrace_nprobes = 0;
        }

        dtrace_hash_destroy(dtrace_bymod);
        dtrace_hash_destroy(dtrace_byfunc);
        dtrace_hash_destroy(dtrace_byname);
        dtrace_bymod = NULL;
        dtrace_byfunc = NULL;
        dtrace_byname = NULL;

        kmem_cache_destroy(dtrace_state_cache);

        delete_unrhdr(dtrace_arena);

        if (dtrace_toxrange != NULL) {
                kmem_free(dtrace_toxrange, 0);
                dtrace_toxrange = NULL;
                dtrace_toxranges = 0;
                dtrace_toxranges_max = 0;
        }

        ASSERT(dtrace_vtime_references == 0);
        ASSERT(dtrace_opens == 0);
        ASSERT(dtrace_retained == NULL);

        mutex_exit(&dtrace_lock);
        mutex_exit(&dtrace_provider_lock);

        mutex_destroy(&dtrace_meta_lock);
        mutex_destroy(&dtrace_provider_lock);
        mutex_destroy(&dtrace_lock);
#ifdef DEBUG
        mutex_destroy(&dtrace_errlock);
#endif

        taskq_destroy(dtrace_taskq);

        /* Reset our hook for exceptions. */
        dtrace_invop_uninit();

        /*
         * Reset our hook for thread switches, but ensure that vtime isn't
         * active first.
         */
        dtrace_vtime_active = 0;
        dtrace_vtime_switch_func = NULL;

        /* Unhook from the trap handler. */
        dtrace_trap_func = NULL;

        return (error);
}