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>
293 lines
6.8 KiB
C
293 lines
6.8 KiB
C
/*
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* linux/arch/arm/mach-omap1/board-voiceblue.c
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*
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* Modified from board-generic.c
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*
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* Copyright (C) 2004 2N Telekomunikace, Ladislav Michl <michl@2n.cz>
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*
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* Code for OMAP5910 based VoiceBlue board (VoIP to GSM gateway).
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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 version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/delay.h>
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#include <linux/platform_device.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/serial_8250.h>
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#include <linux/serial_reg.h>
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#include <asm/hardware.h>
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#include <asm/mach-types.h>
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#include <asm/mach/arch.h>
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#include <asm/mach/flash.h>
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#include <asm/mach/map.h>
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#include <asm/arch/common.h>
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#include <asm/arch/gpio.h>
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#include <asm/arch/mux.h>
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#include <asm/arch/tc.h>
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#include <asm/arch/usb.h>
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extern void omap_init_time(void);
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extern int omap_gpio_init(void);
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static struct plat_serial8250_port voiceblue_ports[] = {
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{
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.mapbase = (unsigned long)(OMAP_CS1_PHYS + 0x40000),
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.irq = OMAP_GPIO_IRQ(12),
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.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP,
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.iotype = UPIO_MEM,
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.regshift = 1,
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.uartclk = 3686400,
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},
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{
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.mapbase = (unsigned long)(OMAP_CS1_PHYS + 0x50000),
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.irq = OMAP_GPIO_IRQ(13),
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.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP,
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.iotype = UPIO_MEM,
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.regshift = 1,
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.uartclk = 3686400,
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},
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{
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.mapbase = (unsigned long)(OMAP_CS1_PHYS + 0x60000),
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.irq = OMAP_GPIO_IRQ(14),
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.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP,
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.iotype = UPIO_MEM,
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.regshift = 1,
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.uartclk = 3686400,
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},
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{
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.mapbase = (unsigned long)(OMAP_CS1_PHYS + 0x70000),
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.irq = OMAP_GPIO_IRQ(15),
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.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP,
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.iotype = UPIO_MEM,
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.regshift = 1,
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.uartclk = 3686400,
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},
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{ },
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};
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static struct platform_device serial_device = {
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.name = "serial8250",
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.id = PLAT8250_DEV_PLATFORM1,
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.dev = {
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.platform_data = voiceblue_ports,
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},
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};
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static int __init ext_uart_init(void)
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{
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return platform_device_register(&serial_device);
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}
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arch_initcall(ext_uart_init);
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static struct flash_platform_data voiceblue_flash_data = {
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.map_name = "cfi_probe",
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.width = 2,
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};
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static struct resource voiceblue_flash_resource = {
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.start = OMAP_CS0_PHYS,
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.end = OMAP_CS0_PHYS + SZ_32M - 1,
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.flags = IORESOURCE_MEM,
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};
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static struct platform_device voiceblue_flash_device = {
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.name = "omapflash",
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.id = 0,
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.dev = {
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.platform_data = &voiceblue_flash_data,
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},
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.num_resources = 1,
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.resource = &voiceblue_flash_resource,
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};
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static struct resource voiceblue_smc91x_resources[] = {
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[0] = {
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.start = OMAP_CS2_PHYS + 0x300,
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.end = OMAP_CS2_PHYS + 0x300 + 16,
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.flags = IORESOURCE_MEM,
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},
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[1] = {
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.start = OMAP_GPIO_IRQ(8),
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.end = OMAP_GPIO_IRQ(8),
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.flags = IORESOURCE_IRQ,
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},
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};
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static struct platform_device voiceblue_smc91x_device = {
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.name = "smc91x",
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.id = 0,
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.num_resources = ARRAY_SIZE(voiceblue_smc91x_resources),
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.resource = voiceblue_smc91x_resources,
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};
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static struct platform_device *voiceblue_devices[] __initdata = {
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&voiceblue_flash_device,
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&voiceblue_smc91x_device,
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};
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static struct omap_usb_config voiceblue_usb_config __initdata = {
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.hmc_mode = 3,
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.register_host = 1,
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.register_dev = 1,
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.pins[0] = 2,
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.pins[1] = 6,
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.pins[2] = 6,
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};
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static struct omap_mmc_config voiceblue_mmc_config __initdata = {
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.mmc[0] = {
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.enabled = 1,
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.power_pin = 2,
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.switch_pin = -1,
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},
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};
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static struct omap_uart_config voiceblue_uart_config __initdata = {
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.enabled_uarts = ((1 << 0) | (1 << 1) | (1 << 2)),
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};
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static struct omap_board_config_kernel voiceblue_config[] = {
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{ OMAP_TAG_USB, &voiceblue_usb_config },
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{ OMAP_TAG_MMC, &voiceblue_mmc_config },
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{ OMAP_TAG_UART, &voiceblue_uart_config },
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};
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static void __init voiceblue_init_irq(void)
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{
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omap1_init_common_hw();
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omap_init_irq();
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omap_gpio_init();
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}
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static void __init voiceblue_init(void)
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{
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/* Watchdog */
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omap_request_gpio(0);
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/* smc91x reset */
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omap_request_gpio(7);
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omap_set_gpio_direction(7, 0);
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omap_set_gpio_dataout(7, 1);
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udelay(2); /* wait at least 100ns */
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omap_set_gpio_dataout(7, 0);
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mdelay(50); /* 50ms until PHY ready */
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/* smc91x interrupt pin */
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omap_request_gpio(8);
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/* 16C554 reset*/
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omap_request_gpio(6);
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omap_set_gpio_direction(6, 0);
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omap_set_gpio_dataout(6, 0);
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/* 16C554 interrupt pins */
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omap_request_gpio(12);
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omap_request_gpio(13);
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omap_request_gpio(14);
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omap_request_gpio(15);
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set_irq_type(OMAP_GPIO_IRQ(12), IRQT_RISING);
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set_irq_type(OMAP_GPIO_IRQ(13), IRQT_RISING);
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set_irq_type(OMAP_GPIO_IRQ(14), IRQT_RISING);
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set_irq_type(OMAP_GPIO_IRQ(15), IRQT_RISING);
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platform_add_devices(voiceblue_devices, ARRAY_SIZE(voiceblue_devices));
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omap_board_config = voiceblue_config;
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omap_board_config_size = ARRAY_SIZE(voiceblue_config);
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omap_serial_init();
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/* There is a good chance board is going up, so enable power LED
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* (it is connected through invertor) */
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omap_writeb(0x00, OMAP_LPG1_LCR);
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omap_writeb(0x00, OMAP_LPG1_PMR); /* Disable clock */
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}
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static void __init voiceblue_map_io(void)
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{
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omap1_map_common_io();
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}
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#define MACHINE_PANICED 1
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#define MACHINE_REBOOTING 2
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#define MACHINE_REBOOT 4
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static unsigned long machine_state;
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static int panic_event(struct notifier_block *this, unsigned long event,
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void *ptr)
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{
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if (test_and_set_bit(MACHINE_PANICED, &machine_state))
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return NOTIFY_DONE;
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/* Flash power LED */
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omap_writeb(0x78, OMAP_LPG1_LCR);
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omap_writeb(0x01, OMAP_LPG1_PMR); /* Enable clock */
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return NOTIFY_DONE;
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}
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static struct notifier_block panic_block = {
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.notifier_call = panic_event,
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};
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static int __init voiceblue_setup(void)
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{
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/* Setup panic notifier */
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atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
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return 0;
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}
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postcore_initcall(voiceblue_setup);
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static int wdt_gpio_state;
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void voiceblue_wdt_enable(void)
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{
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omap_set_gpio_direction(0, 0);
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omap_set_gpio_dataout(0, 0);
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omap_set_gpio_dataout(0, 1);
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omap_set_gpio_dataout(0, 0);
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wdt_gpio_state = 0;
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}
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void voiceblue_wdt_disable(void)
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{
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omap_set_gpio_dataout(0, 0);
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omap_set_gpio_dataout(0, 1);
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omap_set_gpio_dataout(0, 0);
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omap_set_gpio_direction(0, 1);
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}
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void voiceblue_wdt_ping(void)
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{
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if (test_bit(MACHINE_REBOOT, &machine_state))
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return;
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wdt_gpio_state = !wdt_gpio_state;
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omap_set_gpio_dataout(0, wdt_gpio_state);
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}
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void voiceblue_reset(void)
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{
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set_bit(MACHINE_REBOOT, &machine_state);
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voiceblue_wdt_enable();
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while (1) ;
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}
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EXPORT_SYMBOL(voiceblue_wdt_enable);
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EXPORT_SYMBOL(voiceblue_wdt_disable);
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EXPORT_SYMBOL(voiceblue_wdt_ping);
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MACHINE_START(VOICEBLUE, "VoiceBlue OMAP5910")
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/* Maintainer: Ladislav Michl <michl@2n.cz> */
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.phys_io = 0xfff00000,
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.io_pg_offst = ((0xfef00000) >> 18) & 0xfffc,
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.boot_params = 0x10000100,
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.map_io = voiceblue_map_io,
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.init_irq = voiceblue_init_irq,
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.init_machine = voiceblue_init,
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.timer = &omap_timer,
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MACHINE_END
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