8b8a7c43a9
are places where the "main thread" of the booting kernel (either the thread which later becomes swapper or the thread which later becomes init) has to stop and wait for action to take place in another thread before continuing. There are currently three such holds: 1. The intr_config_hooks SYSINIT waits for hooks registered via the config_intrhook_establish function; this allows (typically) devices which need interrupts enabled to complete their initialization to do so before root is mounted. 2. The g_waitidle function waits for the GEOM event queue to be empty; this ensures that all of the disks which have been attached have been tasted before we attempt to mount root. 3. The vfs_mountroot_wait function (in addition to calling g_waitidle) waits for holds registered via root_mount_hold; among other things, this is used by the USB subsystem to ensure that we don't fail to mount root if it's located on a USB disk which takes a while to probe.
275 lines
7.7 KiB
C
275 lines
7.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This software was developed by the Computer Systems Engineering group
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* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
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* contributed to Berkeley.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)subr_autoconf.c 8.1 (Berkeley) 6/10/93
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ddb.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/linker.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/systm.h>
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/*
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* Autoconfiguration subroutines.
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*/
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/*
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* "Interrupt driven config" functions.
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*/
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static TAILQ_HEAD(, intr_config_hook) intr_config_hook_list =
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TAILQ_HEAD_INITIALIZER(intr_config_hook_list);
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static struct intr_config_hook *next_to_notify;
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static struct mtx intr_config_hook_lock;
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MTX_SYSINIT(intr_config_hook, &intr_config_hook_lock, "intr config", MTX_DEF);
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/* ARGSUSED */
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static void run_interrupt_driven_config_hooks(void);
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/*
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* Private data and a shim function for implementing config_interhook_oneshot().
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*/
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struct oneshot_config_hook {
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struct intr_config_hook
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och_hook; /* Must be first */
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ich_func_t och_func;
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void *och_arg;
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};
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static void
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config_intrhook_oneshot_func(void *arg)
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{
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struct oneshot_config_hook *ohook;
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ohook = arg;
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ohook->och_func(ohook->och_arg);
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config_intrhook_disestablish(&ohook->och_hook);
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free(ohook, M_DEVBUF);
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}
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/*
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* If we wait too long for an interrupt-driven config hook to return, print
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* a diagnostic.
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*/
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#define WARNING_INTERVAL_SECS 60
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static void
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run_interrupt_driven_config_hooks_warning(int warned)
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{
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struct intr_config_hook *hook_entry;
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char namebuf[64];
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long offset;
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if (warned < 6) {
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printf("run_interrupt_driven_hooks: still waiting after %d "
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"seconds for", warned * WARNING_INTERVAL_SECS);
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TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links) {
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if (linker_search_symbol_name(
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(caddr_t)hook_entry->ich_func, namebuf,
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sizeof(namebuf), &offset) == 0)
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printf(" %s", namebuf);
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else
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printf(" %p", hook_entry->ich_func);
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}
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printf("\n");
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}
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KASSERT(warned < 6,
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("run_interrupt_driven_config_hooks: waited too long"));
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}
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static void
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run_interrupt_driven_config_hooks()
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{
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static int running;
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struct intr_config_hook *hook_entry;
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mtx_lock(&intr_config_hook_lock);
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/*
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* If hook processing is already active, any newly
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* registered hooks will eventually be notified.
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* Let the currently running session issue these
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* notifications.
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*/
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if (running != 0) {
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mtx_unlock(&intr_config_hook_lock);
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return;
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}
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running = 1;
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while (next_to_notify != NULL) {
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hook_entry = next_to_notify;
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next_to_notify = TAILQ_NEXT(hook_entry, ich_links);
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mtx_unlock(&intr_config_hook_lock);
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(*hook_entry->ich_func)(hook_entry->ich_arg);
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mtx_lock(&intr_config_hook_lock);
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}
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running = 0;
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mtx_unlock(&intr_config_hook_lock);
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}
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static void
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boot_run_interrupt_driven_config_hooks(void *dummy)
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{
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int warned;
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run_interrupt_driven_config_hooks();
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/* Block boot processing until all hooks are disestablished. */
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TSWAIT("config hooks");
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mtx_lock(&intr_config_hook_lock);
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warned = 0;
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while (!TAILQ_EMPTY(&intr_config_hook_list)) {
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if (msleep(&intr_config_hook_list, &intr_config_hook_lock,
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0, "conifhk", WARNING_INTERVAL_SECS * hz) ==
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EWOULDBLOCK) {
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mtx_unlock(&intr_config_hook_lock);
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warned++;
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run_interrupt_driven_config_hooks_warning(warned);
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mtx_lock(&intr_config_hook_lock);
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}
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}
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mtx_unlock(&intr_config_hook_lock);
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TSUNWAIT("config hooks");
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}
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SYSINIT(intr_config_hooks, SI_SUB_INT_CONFIG_HOOKS, SI_ORDER_FIRST,
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boot_run_interrupt_driven_config_hooks, NULL);
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/*
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* Register a hook that will be called after "cold"
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* autoconfiguration is complete and interrupts can
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* be used to complete initialization.
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*/
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int
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config_intrhook_establish(struct intr_config_hook *hook)
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{
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struct intr_config_hook *hook_entry;
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TSHOLD("config hooks");
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mtx_lock(&intr_config_hook_lock);
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TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links)
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if (hook_entry == hook)
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break;
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if (hook_entry != NULL) {
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mtx_unlock(&intr_config_hook_lock);
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printf("config_intrhook_establish: establishing an "
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"already established hook.\n");
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return (1);
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}
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TAILQ_INSERT_TAIL(&intr_config_hook_list, hook, ich_links);
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if (next_to_notify == NULL)
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next_to_notify = hook;
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mtx_unlock(&intr_config_hook_lock);
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if (cold == 0)
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/*
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* XXX Call from a task since not all drivers expect
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* to be re-entered at the time a hook is established.
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*/
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/* XXX Sufficient for modules loaded after initial config??? */
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run_interrupt_driven_config_hooks();
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return (0);
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}
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/*
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* Register a hook function that is automatically unregistered after it runs.
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*/
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void
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config_intrhook_oneshot(ich_func_t func, void *arg)
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{
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struct oneshot_config_hook *ohook;
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ohook = malloc(sizeof(*ohook), M_DEVBUF, M_WAITOK);
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ohook->och_func = func;
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ohook->och_arg = arg;
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ohook->och_hook.ich_func = config_intrhook_oneshot_func;
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ohook->och_hook.ich_arg = ohook;
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config_intrhook_establish(&ohook->och_hook);
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}
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void
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config_intrhook_disestablish(struct intr_config_hook *hook)
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{
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struct intr_config_hook *hook_entry;
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mtx_lock(&intr_config_hook_lock);
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TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links)
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if (hook_entry == hook)
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break;
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if (hook_entry == NULL)
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panic("config_intrhook_disestablish: disestablishing an "
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"unestablished hook");
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if (next_to_notify == hook)
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next_to_notify = TAILQ_NEXT(hook, ich_links);
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TAILQ_REMOVE(&intr_config_hook_list, hook, ich_links);
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TSRELEASE("config hooks");
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/* Wakeup anyone watching the list */
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wakeup(&intr_config_hook_list);
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mtx_unlock(&intr_config_hook_lock);
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}
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#ifdef DDB
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#include <ddb/ddb.h>
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DB_SHOW_COMMAND(conifhk, db_show_conifhk)
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{
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struct intr_config_hook *hook_entry;
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char namebuf[64];
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long offset;
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TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links) {
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if (linker_ddb_search_symbol_name(
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(caddr_t)hook_entry->ich_func, namebuf, sizeof(namebuf),
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&offset) == 0) {
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db_printf("hook: %p at %s+%#lx arg: %p\n",
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hook_entry->ich_func, namebuf, offset,
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hook_entry->ich_arg);
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} else {
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db_printf("hook: %p at ??+?? arg %p\n",
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hook_entry->ich_func, hook_entry->ich_arg);
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}
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}
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}
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#endif /* DDB */
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