kernel-ark/arch/mips/lasat/setup.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

190 lines
4.8 KiB
C

/*
* Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999 MIPS Technologies, Inc. All rights reserved.
*
* Thomas Horsten <thh@lasat.com>
* Copyright (C) 2000 LASAT Networks A/S.
*
* Brian Murphy <brian@murphy.dk>
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* Lasat specific setup.
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <asm/time.h>
#include <asm/cpu.h>
#include <asm/bootinfo.h>
#include <asm/irq.h>
#include <asm/serial.h>
#include <asm/lasat/lasat.h>
#include <asm/lasat/serial.h>
#ifdef CONFIG_PICVUE
#include <linux/notifier.h>
#endif
#include "ds1603.h"
#include <asm/lasat/ds1603.h>
#include <asm/lasat/picvue.h>
#include <asm/lasat/eeprom.h>
#include "prom.h"
int lasat_command_line = 0;
void lasatint_init(void);
extern void lasat_reboot_setup(void);
extern void pcisetup(void);
extern void edhac_init(void *, void *, void *);
extern void addrflt_init(void);
struct lasat_misc lasat_misc_info[N_MACHTYPES] = {
{(void *)KSEG1ADDR(0x1c840000), (void *)KSEG1ADDR(0x1c800000), 2},
{(void *)KSEG1ADDR(0x11080000), (void *)KSEG1ADDR(0x11000000), 6}
};
struct lasat_misc *lasat_misc = NULL;
#ifdef CONFIG_DS1603
static struct ds_defs ds_defs[N_MACHTYPES] = {
{ (void *)DS1603_REG_100, (void *)DS1603_REG_100,
DS1603_RST_100, DS1603_CLK_100, DS1603_DATA_100,
DS1603_DATA_SHIFT_100, 0, 0 },
{ (void *)DS1603_REG_200, (void *)DS1603_DATA_REG_200,
DS1603_RST_200, DS1603_CLK_200, DS1603_DATA_200,
DS1603_DATA_READ_SHIFT_200, 1, 2000 }
};
#endif
#ifdef CONFIG_PICVUE
#include "picvue.h"
static struct pvc_defs pvc_defs[N_MACHTYPES] = {
{ (void *)PVC_REG_100, PVC_DATA_SHIFT_100, PVC_DATA_M_100,
PVC_E_100, PVC_RW_100, PVC_RS_100 },
{ (void *)PVC_REG_200, PVC_DATA_SHIFT_200, PVC_DATA_M_200,
PVC_E_200, PVC_RW_200, PVC_RS_200 }
};
#endif
static int lasat_panic_display(struct notifier_block *this,
unsigned long event, void *ptr)
{
#ifdef CONFIG_PICVUE
unsigned char *string = ptr;
if (string == NULL)
string = "Kernel Panic";
pvc_dump_string(string);
#endif
return NOTIFY_DONE;
}
static int lasat_panic_prom_monitor(struct notifier_block *this,
unsigned long event, void *ptr)
{
prom_monitor();
return NOTIFY_DONE;
}
static struct notifier_block lasat_panic_block[] =
{
{ lasat_panic_display, NULL, INT_MAX },
{ lasat_panic_prom_monitor, NULL, INT_MIN }
};
static void lasat_time_init(void)
{
mips_hpt_frequency = lasat_board_info.li_cpu_hz / 2;
}
static void lasat_timer_setup(struct irqaction *irq)
{
write_c0_compare(
read_c0_count() +
mips_hpt_frequency / HZ);
change_c0_status(ST0_IM, IE_IRQ0 | IE_IRQ5);
}
#define DYNAMIC_SERIAL_INIT
#ifdef DYNAMIC_SERIAL_INIT
void __init serial_init(void)
{
#ifdef CONFIG_SERIAL_8250
struct uart_port s;
memset(&s, 0, sizeof(s));
s.flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST;
s.iotype = UPIO_MEM;
if (mips_machtype == MACH_LASAT_100) {
s.uartclk = LASAT_BASE_BAUD_100 * 16;
s.irq = LASATINT_UART_100;
s.regshift = LASAT_UART_REGS_SHIFT_100;
s.membase = (char *)KSEG1ADDR(LASAT_UART_REGS_BASE_100);
} else {
s.uartclk = LASAT_BASE_BAUD_200 * 16;
s.irq = LASATINT_UART_200;
s.regshift = LASAT_UART_REGS_SHIFT_200;
s.membase = (char *)KSEG1ADDR(LASAT_UART_REGS_BASE_200);
}
if (early_serial_setup(&s) != 0)
printk(KERN_ERR "Serial setup failed!\n");
#endif
}
#endif
void __init plat_setup(void)
{
int i;
lasat_misc = &lasat_misc_info[mips_machtype];
#ifdef CONFIG_PICVUE
picvue = &pvc_defs[mips_machtype];
#endif
/* Set up panic notifier */
for (i = 0; i < sizeof(lasat_panic_block) / sizeof(struct notifier_block); i++)
atomic_notifier_chain_register(&panic_notifier_list,
&lasat_panic_block[i]);
lasat_reboot_setup();
board_time_init = lasat_time_init;
board_timer_setup = lasat_timer_setup;
#ifdef CONFIG_DS1603
ds1603 = &ds_defs[mips_machtype];
rtc_get_time = ds1603_read;
rtc_set_time = ds1603_set;
#endif
#ifdef DYNAMIC_SERIAL_INIT
serial_init();
#endif
/* Switch from prom exception handler to normal mode */
change_c0_status(ST0_BEV,0);
prom_printf("Lasat specific initialization complete\n");
}