linux/arch/parisc/kernel/pdc_chassis.c
Alan Stern e041c68341 [PATCH] Notifier chain update: API changes
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>
2006-03-27 08:44:50 -08:00

248 lines
6.6 KiB
C

/*
* interfaces to log Chassis Codes via PDC (firmware)
*
* Copyright (C) 2002 Laurent Canet <canetl@esiee.fr>
* Copyright (C) 2002-2004 Thibaut VARENE <varenet@parisc-linux.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#undef PDC_CHASSIS_DEBUG
#ifdef PDC_CHASSIS_DEBUG
#define DPRINTK(fmt, args...) printk(fmt, ## args)
#else
#define DPRINTK(fmt, args...)
#endif
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
#include <linux/cache.h>
#include <asm/pdc_chassis.h>
#include <asm/processor.h>
#include <asm/pdc.h>
#include <asm/pdcpat.h>
#ifdef CONFIG_PDC_CHASSIS
static int pdc_chassis_old __read_mostly = 0;
static unsigned int pdc_chassis_enabled __read_mostly = 1;
/**
* pdc_chassis_setup() - Enable/disable pdc_chassis code at boot time.
* @str configuration param: 0 to disable chassis log
* @return 1
*/
static int __init pdc_chassis_setup(char *str)
{
/*panic_timeout = simple_strtoul(str, NULL, 0);*/
get_option(&str, &pdc_chassis_enabled);
return 1;
}
__setup("pdcchassis=", pdc_chassis_setup);
/**
* pdc_chassis_checkold() - Checks for old PDC_CHASSIS compatibility
* @pdc_chassis_old: 1 if old pdc chassis style
*
* Currently, only E class and A180 are known to work with this.
* Inspired by Christoph Plattner
*/
static void __init pdc_chassis_checkold(void)
{
switch(CPU_HVERSION) {
case 0x480: /* E25 */
case 0x481: /* E35 */
case 0x482: /* E45 */
case 0x483: /* E55 */
case 0x516: /* A180 */
pdc_chassis_old = 1;
break;
default:
break;
}
DPRINTK(KERN_DEBUG "%s: pdc_chassis_checkold(); pdc_chassis_old = %d\n", __FILE__, pdc_chassis_old);
}
/**
* pdc_chassis_panic_event() - Called by the panic handler.
*
* As soon as a panic occurs, we should inform the PDC.
*/
static int pdc_chassis_panic_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
return NOTIFY_DONE;
}
static struct notifier_block pdc_chassis_panic_block = {
.notifier_call = pdc_chassis_panic_event,
.priority = INT_MAX,
};
/**
* parisc_reboot_event() - Called by the reboot handler.
*
* As soon as a reboot occurs, we should inform the PDC.
*/
static int pdc_chassis_reboot_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
pdc_chassis_send_status(PDC_CHASSIS_DIRECT_SHUTDOWN);
return NOTIFY_DONE;
}
static struct notifier_block pdc_chassis_reboot_block = {
.notifier_call = pdc_chassis_reboot_event,
.priority = INT_MAX,
};
#endif /* CONFIG_PDC_CHASSIS */
/**
* parisc_pdc_chassis_init() - Called at boot time.
*/
void __init parisc_pdc_chassis_init(void)
{
#ifdef CONFIG_PDC_CHASSIS
int handle = 0;
if (likely(pdc_chassis_enabled)) {
DPRINTK(KERN_DEBUG "%s: parisc_pdc_chassis_init()\n", __FILE__);
/* Let see if we have something to handle... */
/* Check for PDC_PAT or old LED Panel */
pdc_chassis_checkold();
if (is_pdc_pat()) {
printk(KERN_INFO "Enabling PDC_PAT chassis codes support.\n");
handle = 1;
}
else if (unlikely(pdc_chassis_old)) {
printk(KERN_INFO "Enabling old style chassis LED panel support.\n");
handle = 1;
}
if (handle) {
/* initialize panic notifier chain */
atomic_notifier_chain_register(&panic_notifier_list,
&pdc_chassis_panic_block);
/* initialize reboot notifier chain */
register_reboot_notifier(&pdc_chassis_reboot_block);
}
}
#endif /* CONFIG_PDC_CHASSIS */
}
/**
* pdc_chassis_send_status() - Sends a predefined message to the chassis,
* and changes the front panel LEDs according to the new system state
* @retval: PDC call return value.
*
* Only machines with 64 bits PDC PAT and those reported in
* pdc_chassis_checkold() are supported atm.
*
* returns 0 if no error, -1 if no supported PDC is present or invalid message,
* else returns the appropriate PDC error code.
*
* For a list of predefined messages, see asm-parisc/pdc_chassis.h
*/
int pdc_chassis_send_status(int message)
{
/* Maybe we should do that in an other way ? */
int retval = 0;
#ifdef CONFIG_PDC_CHASSIS
if (likely(pdc_chassis_enabled)) {
DPRINTK(KERN_DEBUG "%s: pdc_chassis_send_status(%d)\n", __FILE__, message);
#ifdef CONFIG_64BIT
if (is_pdc_pat()) {
switch(message) {
case PDC_CHASSIS_DIRECT_BSTART:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_BSTART, PDC_CHASSIS_LSTATE_RUN_NORMAL);
break;
case PDC_CHASSIS_DIRECT_BCOMPLETE:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_BCOMPLETE, PDC_CHASSIS_LSTATE_RUN_NORMAL);
break;
case PDC_CHASSIS_DIRECT_SHUTDOWN:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_SHUTDOWN, PDC_CHASSIS_LSTATE_NONOS);
break;
case PDC_CHASSIS_DIRECT_PANIC:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_PANIC, PDC_CHASSIS_LSTATE_RUN_CRASHREC);
break;
case PDC_CHASSIS_DIRECT_LPMC:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_LPMC, PDC_CHASSIS_LSTATE_RUN_SYSINT);
break;
case PDC_CHASSIS_DIRECT_HPMC:
retval = pdc_pat_chassis_send_log(PDC_CHASSIS_PMSG_HPMC, PDC_CHASSIS_LSTATE_RUN_NCRIT);
break;
default:
retval = -1;
}
} else retval = -1;
#else
if (unlikely(pdc_chassis_old)) {
switch (message) {
case PDC_CHASSIS_DIRECT_BSTART:
case PDC_CHASSIS_DIRECT_BCOMPLETE:
retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_RUN));
break;
case PDC_CHASSIS_DIRECT_SHUTDOWN:
retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_SHUT));
break;
case PDC_CHASSIS_DIRECT_HPMC:
case PDC_CHASSIS_DIRECT_PANIC:
retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_FLT));
break;
case PDC_CHASSIS_DIRECT_LPMC:
retval = pdc_chassis_disp(PDC_CHASSIS_DISP_DATA(OSTAT_WARN));
break;
default:
retval = -1;
}
} else retval = -1;
#endif /* CONFIG_64BIT */
} /* if (pdc_chassis_enabled) */
#endif /* CONFIG_PDC_CHASSIS */
return retval;
}