forked from Minki/linux
e041c68341
The kernel's implementation of notifier chains is unsafe. There is no protection against entries being added to or removed from a chain while the chain is in use. The issues were discussed in this thread: http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2 We noticed that notifier chains in the kernel fall into two basic usage classes: "Blocking" chains are always called from a process context and the callout routines are allowed to sleep; "Atomic" chains can be called from an atomic context and the callout routines are not allowed to sleep. We decided to codify this distinction and make it part of the API. Therefore this set of patches introduces three new, parallel APIs: one for blocking notifiers, one for atomic notifiers, and one for "raw" notifiers (which is really just the old API under a new name). New kinds of data structures are used for the heads of the chains, and new routines are defined for registration, unregistration, and calling a chain. The three APIs are explained in include/linux/notifier.h and their implementation is in kernel/sys.c. With atomic and blocking chains, the implementation guarantees that the chain links will not be corrupted and that chain callers will not get messed up by entries being added or removed. For raw chains the implementation provides no guarantees at all; users of this API must provide their own protections. (The idea was that situations may come up where the assumptions of the atomic and blocking APIs are not appropriate, so it should be possible for users to handle these things in their own way.) There are some limitations, which should not be too hard to live with. For atomic/blocking chains, registration and unregistration must always be done in a process context since the chain is protected by a mutex/rwsem. Also, a callout routine for a non-raw chain must not try to register or unregister entries on its own chain. (This did happen in a couple of places and the code had to be changed to avoid it.) Since atomic chains may be called from within an NMI handler, they cannot use spinlocks for synchronization. Instead we use RCU. The overhead falls almost entirely in the unregister routine, which is okay since unregistration is much less frequent that calling a chain. Here is the list of chains that we adjusted and their classifications. None of them use the raw API, so for the moment it is only a placeholder. ATOMIC CHAINS ------------- arch/i386/kernel/traps.c: i386die_chain arch/ia64/kernel/traps.c: ia64die_chain arch/powerpc/kernel/traps.c: powerpc_die_chain arch/sparc64/kernel/traps.c: sparc64die_chain arch/x86_64/kernel/traps.c: die_chain drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list kernel/panic.c: panic_notifier_list kernel/profile.c: task_free_notifier net/bluetooth/hci_core.c: hci_notifier net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain net/ipv6/addrconf.c: inet6addr_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain net/netlink/af_netlink.c: netlink_chain BLOCKING CHAINS --------------- arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain arch/s390/kernel/process.c: idle_chain arch/x86_64/kernel/process.c idle_notifier drivers/base/memory.c: memory_chain drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list drivers/macintosh/adb.c: adb_client_list drivers/macintosh/via-pmu.c sleep_notifier_list drivers/macintosh/via-pmu68k.c sleep_notifier_list drivers/macintosh/windfarm_core.c wf_client_list drivers/usb/core/notify.c usb_notifier_list drivers/video/fbmem.c fb_notifier_list kernel/cpu.c cpu_chain kernel/module.c module_notify_list kernel/profile.c munmap_notifier kernel/profile.c task_exit_notifier kernel/sys.c reboot_notifier_list net/core/dev.c netdev_chain net/decnet/dn_dev.c: dnaddr_chain net/ipv4/devinet.c: inetaddr_chain It's possible that some of these classifications are wrong. If they are, please let us know or submit a patch to fix them. Note that any chain that gets called very frequently should be atomic, because the rwsem read-locking used for blocking chains is very likely to incur cache misses on SMP systems. (However, if the chain's callout routines may sleep then the chain cannot be atomic.) The patch set was written by Alan Stern and Chandra Seetharaman, incorporating material written by Keith Owens and suggestions from Paul McKenney and Andrew Morton. [jes@sgi.com: restructure the notifier chain initialization macros] Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
248 lines
6.6 KiB
C
248 lines
6.6 KiB
C
/*
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* interfaces to log Chassis Codes via PDC (firmware)
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*
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* Copyright (C) 2002 Laurent Canet <canetl@esiee.fr>
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* Copyright (C) 2002-2004 Thibaut VARENE <varenet@parisc-linux.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#undef PDC_CHASSIS_DEBUG
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#ifdef PDC_CHASSIS_DEBUG
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#define DPRINTK(fmt, args...) printk(fmt, ## args)
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#else
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#define DPRINTK(fmt, args...)
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#endif
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/reboot.h>
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#include <linux/notifier.h>
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#include <linux/cache.h>
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#include <asm/pdc_chassis.h>
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#include <asm/processor.h>
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#include <asm/pdc.h>
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#include <asm/pdcpat.h>
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#ifdef CONFIG_PDC_CHASSIS
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static int pdc_chassis_old __read_mostly = 0;
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static unsigned int pdc_chassis_enabled __read_mostly = 1;
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/**
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* pdc_chassis_setup() - Enable/disable pdc_chassis code at boot time.
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* @str configuration param: 0 to disable chassis log
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* @return 1
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*/
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static int __init pdc_chassis_setup(char *str)
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{
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/*panic_timeout = simple_strtoul(str, NULL, 0);*/
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get_option(&str, &pdc_chassis_enabled);
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return 1;
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}
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__setup("pdcchassis=", pdc_chassis_setup);
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/**
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* pdc_chassis_checkold() - Checks for old PDC_CHASSIS compatibility
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* @pdc_chassis_old: 1 if old pdc chassis style
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*
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* Currently, only E class and A180 are known to work with this.
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* Inspired by Christoph Plattner
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*/
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static void __init pdc_chassis_checkold(void)
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{
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switch(CPU_HVERSION) {
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case 0x480: /* E25 */
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case 0x481: /* E35 */
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case 0x482: /* E45 */
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case 0x483: /* E55 */
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case 0x516: /* A180 */
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pdc_chassis_old = 1;
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break;
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default:
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break;
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}
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DPRINTK(KERN_DEBUG "%s: pdc_chassis_checkold(); pdc_chassis_old = %d\n", __FILE__, pdc_chassis_old);
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}
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/**
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* pdc_chassis_panic_event() - Called by the panic handler.
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*
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* As soon as a panic occurs, we should inform the PDC.
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*/
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static int pdc_chassis_panic_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
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return NOTIFY_DONE;
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}
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static struct notifier_block pdc_chassis_panic_block = {
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.notifier_call = pdc_chassis_panic_event,
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.priority = INT_MAX,
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};
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/**
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* parisc_reboot_event() - Called by the reboot handler.
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*
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* As soon as a reboot occurs, we should inform the PDC.
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*/
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static int pdc_chassis_reboot_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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pdc_chassis_send_status(PDC_CHASSIS_DIRECT_SHUTDOWN);
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return NOTIFY_DONE;
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}
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static struct notifier_block pdc_chassis_reboot_block = {
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.notifier_call = pdc_chassis_reboot_event,
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.priority = INT_MAX,
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};
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#endif /* CONFIG_PDC_CHASSIS */
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/**
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* parisc_pdc_chassis_init() - Called at boot time.
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*/
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void __init parisc_pdc_chassis_init(void)
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{
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#ifdef CONFIG_PDC_CHASSIS
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int handle = 0;
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if (likely(pdc_chassis_enabled)) {
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DPRINTK(KERN_DEBUG "%s: parisc_pdc_chassis_init()\n", __FILE__);
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/* Let see if we have something to handle... */
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/* Check for PDC_PAT or old LED Panel */
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pdc_chassis_checkold();
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if (is_pdc_pat()) {
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printk(KERN_INFO "Enabling PDC_PAT chassis codes support.\n");
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handle = 1;
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}
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else if (unlikely(pdc_chassis_old)) {
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printk(KERN_INFO "Enabling old style chassis LED panel support.\n");
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handle = 1;
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}
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if (handle) {
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/* initialize panic notifier chain */
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atomic_notifier_chain_register(&panic_notifier_list,
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&pdc_chassis_panic_block);
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/* initialize reboot notifier chain */
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register_reboot_notifier(&pdc_chassis_reboot_block);
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}
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}
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#endif /* CONFIG_PDC_CHASSIS */
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}
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/**
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* pdc_chassis_send_status() - Sends a predefined message to the chassis,
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* and changes the front panel LEDs according to the new system state
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* @retval: PDC call return value.
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*
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* Only machines with 64 bits PDC PAT and those reported in
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* pdc_chassis_checkold() are supported atm.
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*
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* returns 0 if no error, -1 if no supported PDC is present or invalid message,
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* else returns the appropriate PDC error code.
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*
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* For a list of predefined messages, see asm-parisc/pdc_chassis.h
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*/
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int pdc_chassis_send_status(int message)
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{
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/* Maybe we should do that in an other way ? */
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int retval = 0;
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#ifdef CONFIG_PDC_CHASSIS
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if (likely(pdc_chassis_enabled)) {
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DPRINTK(KERN_DEBUG "%s: pdc_chassis_send_status(%d)\n", __FILE__, message);
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#ifdef CONFIG_64BIT
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if (is_pdc_pat()) {
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switch(message) {
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case PDC_CHASSIS_DIRECT_BSTART:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_BSTART, PDC_CHASSIS_LSTATE_RUN_NORMAL);
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break;
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case PDC_CHASSIS_DIRECT_BCOMPLETE:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_BCOMPLETE, PDC_CHASSIS_LSTATE_RUN_NORMAL);
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break;
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case PDC_CHASSIS_DIRECT_SHUTDOWN:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_SHUTDOWN, PDC_CHASSIS_LSTATE_NONOS);
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break;
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case PDC_CHASSIS_DIRECT_PANIC:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_PANIC, PDC_CHASSIS_LSTATE_RUN_CRASHREC);
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break;
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case PDC_CHASSIS_DIRECT_LPMC:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_LPMC, PDC_CHASSIS_LSTATE_RUN_SYSINT);
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break;
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case PDC_CHASSIS_DIRECT_HPMC:
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retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_HPMC, PDC_CHASSIS_LSTATE_RUN_NCRIT);
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break;
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default:
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retval = -1;
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}
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} else retval = -1;
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#else
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if (unlikely(pdc_chassis_old)) {
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switch (message) {
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case PDC_CHASSIS_DIRECT_BSTART:
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case PDC_CHASSIS_DIRECT_BCOMPLETE:
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retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_RUN));
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break;
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case PDC_CHASSIS_DIRECT_SHUTDOWN:
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retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_SHUT));
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break;
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case PDC_CHASSIS_DIRECT_HPMC:
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case PDC_CHASSIS_DIRECT_PANIC:
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retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_FLT));
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break;
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case PDC_CHASSIS_DIRECT_LPMC:
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retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_WARN));
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break;
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default:
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retval = -1;
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}
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} else retval = -1;
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#endif /* CONFIG_64BIT */
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} /* if (pdc_chassis_enabled) */
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#endif /* CONFIG_PDC_CHASSIS */
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return retval;
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}
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