linux/arch/um/drivers/mconsole_kern.c

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/*
* Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
* Copyright (C) 2001 - 2003 Jeff Dike (jdike@addtoit.com)
* Licensed under the GPL
*/
#include "linux/kernel.h"
#include "linux/slab.h"
#include "linux/init.h"
#include "linux/notifier.h"
#include "linux/reboot.h"
#include "linux/utsname.h"
#include "linux/ctype.h"
#include "linux/interrupt.h"
#include "linux/sysrq.h"
#include "linux/workqueue.h"
#include "linux/module.h"
#include "linux/file.h"
#include "linux/fs.h"
#include "linux/namei.h"
#include "linux/proc_fs.h"
#include "linux/syscalls.h"
#include "linux/list.h"
#include "linux/mm.h"
#include "linux/console.h"
#include "asm/irq.h"
#include "asm/uaccess.h"
#include "kern_util.h"
#include "kern.h"
#include "mconsole.h"
#include "mconsole_kern.h"
#include "irq_user.h"
#include "init.h"
#include "os.h"
#include "irq_kern.h"
#include "choose-mode.h"
static int do_unlink_socket(struct notifier_block *notifier,
unsigned long what, void *data)
{
return(mconsole_unlink_socket());
}
static struct notifier_block reboot_notifier = {
.notifier_call = do_unlink_socket,
.priority = 0,
};
/* Safe without explicit locking for now. Tasklets provide their own
* locking, and the interrupt handler is safe because it can't interrupt
* itself and it can only happen on CPU 0.
*/
static LIST_HEAD(mc_requests);
static void mc_work_proc(struct work_struct *unused)
{
struct mconsole_entry *req;
unsigned long flags;
while(!list_empty(&mc_requests)){
local_irq_save(flags);
req = list_entry(mc_requests.next, struct mconsole_entry,
list);
list_del(&req->list);
local_irq_restore(flags);
req->request.cmd->handler(&req->request);
kfree(req);
}
}
static DECLARE_WORK(mconsole_work, mc_work_proc);
static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
{
/* long to avoid size mismatch warnings from gcc */
long fd;
struct mconsole_entry *new;
static struct mc_request req; /* that's OK */
fd = (long) dev_id;
while (mconsole_get_request(fd, &req)){
if(req.cmd->context == MCONSOLE_INTR)
(*req.cmd->handler)(&req);
else {
new = kmalloc(sizeof(*new), GFP_NOWAIT);
if(new == NULL)
mconsole_reply(&req, "Out of memory", 1, 0);
else {
new->request = req;
new->request.regs = get_irq_regs()->regs;
list_add(&new->list, &mc_requests);
}
}
}
if(!list_empty(&mc_requests))
schedule_work(&mconsole_work);
reactivate_fd(fd, MCONSOLE_IRQ);
return(IRQ_HANDLED);
}
void mconsole_version(struct mc_request *req)
{
char version[256];
sprintf(version, "%s %s %s %s %s", utsname()->sysname,
utsname()->nodename, utsname()->release,
utsname()->version, utsname()->machine);
mconsole_reply(req, version, 0, 0);
}
void mconsole_log(struct mc_request *req)
{
int len;
char *ptr = req->request.data;
ptr += strlen("log ");
len = req->len - (ptr - req->request.data);
printk("%.*s", len, ptr);
mconsole_reply(req, "", 0, 0);
}
/* This is a more convoluted version of mconsole_proc, which has some stability
* problems; however, we need it fixed, because it is expected that UML users
* mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
* show the real procfs content, not the ones from hppfs.*/
#if 0
void mconsole_proc(struct mc_request *req)
{
struct nameidata nd;
struct file_system_type *proc;
struct super_block *super;
struct file *file;
int n, err;
char *ptr = req->request.data, *buf;
ptr += strlen("proc");
while(isspace(*ptr)) ptr++;
proc = get_fs_type("proc");
if(proc == NULL){
mconsole_reply(req, "procfs not registered", 1, 0);
goto out;
}
super = (*proc->get_sb)(proc, 0, NULL, NULL);
put_filesystem(proc);
if(super == NULL){
mconsole_reply(req, "Failed to get procfs superblock", 1, 0);
goto out;
}
up_write(&super->s_umount);
nd.dentry = super->s_root;
nd.mnt = NULL;
nd.flags = O_RDONLY + 1;
nd.last_type = LAST_ROOT;
/* START: it was experienced that the stability problems are closed
* if commenting out these two calls + the below read cycle. To
* make UML crash again, it was enough to readd either one.*/
err = link_path_walk(ptr, &nd);
if(err){
mconsole_reply(req, "Failed to look up file", 1, 0);
goto out_kill;
}
file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
if(IS_ERR(file)){
mconsole_reply(req, "Failed to open file", 1, 0);
goto out_kill;
}
/*END*/
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if(buf == NULL){
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
goto out_fput;
}
if((file->f_op != NULL) && (file->f_op->read != NULL)){
do {
n = (*file->f_op->read)(file, buf, PAGE_SIZE - 1,
&file->f_pos);
if(n >= 0){
buf[n] = '\0';
mconsole_reply(req, buf, 0, (n > 0));
}
else {
mconsole_reply(req, "Read of file failed",
1, 0);
goto out_free;
}
} while(n > 0);
}
else mconsole_reply(req, "", 0, 0);
out_free:
kfree(buf);
out_fput:
fput(file);
out_kill:
deactivate_super(super);
out: ;
}
#endif
void mconsole_proc(struct mc_request *req)
{
char path[64];
char *buf;
int len;
int fd;
int first_chunk = 1;
char *ptr = req->request.data;
ptr += strlen("proc");
while(isspace(*ptr)) ptr++;
snprintf(path, sizeof(path), "/proc/%s", ptr);
fd = sys_open(path, 0, 0);
if (fd < 0) {
mconsole_reply(req, "Failed to open file", 1, 0);
printk("open %s: %d\n",path,fd);
goto out;
}
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if(buf == NULL){
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
goto out_close;
}
for (;;) {
len = sys_read(fd, buf, PAGE_SIZE-1);
if (len < 0) {
mconsole_reply(req, "Read of file failed", 1, 0);
goto out_free;
}
/*Begin the file content on his own line.*/
if (first_chunk) {
mconsole_reply(req, "\n", 0, 1);
first_chunk = 0;
}
if (len == PAGE_SIZE-1) {
buf[len] = '\0';
mconsole_reply(req, buf, 0, 1);
} else {
buf[len] = '\0';
mconsole_reply(req, buf, 0, 0);
break;
}
}
out_free:
kfree(buf);
out_close:
sys_close(fd);
out:
/* nothing */;
}
#define UML_MCONSOLE_HELPTEXT \
"Commands: \n\
version - Get kernel version \n\
help - Print this message \n\
halt - Halt UML \n\
reboot - Reboot UML \n\
config <dev>=<config> - Add a new device to UML; \n\
same syntax as command line \n\
config <dev> - Query the configuration of a device \n\
remove <dev> - Remove a device from UML \n\
sysrq <letter> - Performs the SysRq action controlled by the letter \n\
cad - invoke the Ctrl-Alt-Del handler \n\
stop - pause the UML; it will do nothing until it receives a 'go' \n\
go - continue the UML after a 'stop' \n\
log <string> - make UML enter <string> into the kernel log\n\
proc <file> - returns the contents of the UML's /proc/<file>\n\
stack <pid> - returns the stack of the specified pid\n\
"
void mconsole_help(struct mc_request *req)
{
mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
}
void mconsole_halt(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
machine_halt();
}
void mconsole_reboot(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
machine_restart(NULL);
}
void mconsole_cad(struct mc_request *req)
{
mconsole_reply(req, "", 0, 0);
ctrl_alt_del();
}
void mconsole_go(struct mc_request *req)
{
mconsole_reply(req, "Not stopped", 1, 0);
}
void mconsole_stop(struct mc_request *req)
{
deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
os_set_fd_block(req->originating_fd, 1);
mconsole_reply(req, "stopped", 0, 0);
while (mconsole_get_request(req->originating_fd, req)) {
if (req->cmd->handler == mconsole_go)
break;
if (req->cmd->handler == mconsole_stop) {
mconsole_reply(req, "Already stopped", 1, 0);
continue;
}
if (req->cmd->handler == mconsole_sysrq) {
struct pt_regs *old_regs;
old_regs = set_irq_regs((struct pt_regs *)&req->regs);
mconsole_sysrq(req);
set_irq_regs(old_regs);
continue;
}
(*req->cmd->handler)(req);
}
os_set_fd_block(req->originating_fd, 0);
reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
mconsole_reply(req, "", 0, 0);
}
static DEFINE_SPINLOCK(mc_devices_lock);
static LIST_HEAD(mconsole_devices);
void mconsole_register_dev(struct mc_device *new)
{
spin_lock(&mc_devices_lock);
BUG_ON(!list_empty(&new->list));
list_add(&new->list, &mconsole_devices);
spin_unlock(&mc_devices_lock);
}
static struct mc_device *mconsole_find_dev(char *name)
{
struct list_head *ele;
struct mc_device *dev;
list_for_each(ele, &mconsole_devices){
dev = list_entry(ele, struct mc_device, list);
if(!strncmp(name, dev->name, strlen(dev->name)))
return(dev);
}
return(NULL);
}
#define UNPLUGGED_PER_PAGE \
((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
struct unplugged_pages {
struct list_head list;
void *pages[UNPLUGGED_PER_PAGE];
};
static DECLARE_MUTEX(plug_mem_mutex);
static unsigned long long unplugged_pages_count = 0;
static LIST_HEAD(unplugged_pages);
static int unplug_index = UNPLUGGED_PER_PAGE;
static int mem_config(char *str, char **error_out)
{
unsigned long long diff;
int err = -EINVAL, i, add;
char *ret;
if(str[0] != '='){
*error_out = "Expected '=' after 'mem'";
goto out;
}
str++;
if(str[0] == '-')
add = 0;
else if(str[0] == '+'){
add = 1;
}
else {
*error_out = "Expected increment to start with '-' or '+'";
goto out;
}
str++;
diff = memparse(str, &ret);
if(*ret != '\0'){
*error_out = "Failed to parse memory increment";
goto out;
}
diff /= PAGE_SIZE;
down(&plug_mem_mutex);
for(i = 0; i < diff; i++){
struct unplugged_pages *unplugged;
void *addr;
if(add){
if(list_empty(&unplugged_pages))
break;
unplugged = list_entry(unplugged_pages.next,
struct unplugged_pages, list);
if(unplug_index > 0)
addr = unplugged->pages[--unplug_index];
else {
list_del(&unplugged->list);
addr = unplugged;
unplug_index = UNPLUGGED_PER_PAGE;
}
free_page((unsigned long) addr);
unplugged_pages_count--;
}
else {
struct page *page;
page = alloc_page(GFP_ATOMIC);
if(page == NULL)
break;
unplugged = page_address(page);
if(unplug_index == UNPLUGGED_PER_PAGE){
list_add(&unplugged->list, &unplugged_pages);
unplug_index = 0;
}
else {
struct list_head *entry = unplugged_pages.next;
addr = unplugged;
unplugged = list_entry(entry,
struct unplugged_pages,
list);
err = os_drop_memory(addr, PAGE_SIZE);
if(err){
printk("Failed to release memory - "
"errno = %d\n", err);
*error_out = "Failed to release memory";
goto out_unlock;
}
unplugged->pages[unplug_index++] = addr;
}
unplugged_pages_count++;
}
}
err = 0;
out_unlock:
up(&plug_mem_mutex);
out:
return err;
}
static int mem_get_config(char *name, char *str, int size, char **error_out)
{
char buf[sizeof("18446744073709551615")];
int len = 0;
sprintf(buf, "%ld", uml_physmem);
CONFIG_CHUNK(str, size, len, buf, 1);
return len;
}
static int mem_id(char **str, int *start_out, int *end_out)
{
*start_out = 0;
*end_out = 0;
return 0;
}
static int mem_remove(int n, char **error_out)
{
*error_out = "Memory doesn't support the remove operation";
return -EBUSY;
}
static struct mc_device mem_mc = {
.list = LIST_HEAD_INIT(mem_mc.list),
.name = "mem",
.config = mem_config,
.get_config = mem_get_config,
.id = mem_id,
.remove = mem_remove,
};
static int mem_mc_init(void)
{
if(can_drop_memory())
mconsole_register_dev(&mem_mc);
else printk("Can't release memory to the host - memory hotplug won't "
"be supported\n");
return 0;
}
__initcall(mem_mc_init);
#define CONFIG_BUF_SIZE 64
static void mconsole_get_config(int (*get_config)(char *, char *, int,
char **),
struct mc_request *req, char *name)
{
char default_buf[CONFIG_BUF_SIZE], *error, *buf;
int n, size;
if(get_config == NULL){
mconsole_reply(req, "No get_config routine defined", 1, 0);
return;
}
error = NULL;
size = ARRAY_SIZE(default_buf);
buf = default_buf;
while(1){
n = (*get_config)(name, buf, size, &error);
if(error != NULL){
mconsole_reply(req, error, 1, 0);
goto out;
}
if(n <= size){
mconsole_reply(req, buf, 0, 0);
goto out;
}
if(buf != default_buf)
kfree(buf);
size = n;
buf = kmalloc(size, GFP_KERNEL);
if(buf == NULL){
mconsole_reply(req, "Failed to allocate buffer", 1, 0);
return;
}
}
out:
if(buf != default_buf)
kfree(buf);
}
void mconsole_config(struct mc_request *req)
{
struct mc_device *dev;
char *ptr = req->request.data, *name, *error_string = "";
int err;
ptr += strlen("config");
while(isspace(*ptr)) ptr++;
dev = mconsole_find_dev(ptr);
if(dev == NULL){
mconsole_reply(req, "Bad configuration option", 1, 0);
return;
}
name = &ptr[strlen(dev->name)];
ptr = name;
while((*ptr != '=') && (*ptr != '\0'))
ptr++;
if(*ptr == '='){
err = (*dev->config)(name, &error_string);
mconsole_reply(req, error_string, err, 0);
}
else mconsole_get_config(dev->get_config, req, name);
}
void mconsole_remove(struct mc_request *req)
{
struct mc_device *dev;
char *ptr = req->request.data, *err_msg = "";
char error[256];
int err, start, end, n;
ptr += strlen("remove");
while(isspace(*ptr)) ptr++;
dev = mconsole_find_dev(ptr);
if(dev == NULL){
mconsole_reply(req, "Bad remove option", 1, 0);
return;
}
ptr = &ptr[strlen(dev->name)];
err = 1;
n = (*dev->id)(&ptr, &start, &end);
if(n < 0){
err_msg = "Couldn't parse device number";
goto out;
}
else if((n < start) || (n > end)){
sprintf(error, "Invalid device number - must be between "
"%d and %d", start, end);
err_msg = error;
goto out;
}
err_msg = NULL;
err = (*dev->remove)(n, &err_msg);
switch(err){
case 0:
err_msg = "";
break;
case -ENODEV:
if(err_msg == NULL)
err_msg = "Device doesn't exist";
break;
case -EBUSY:
if(err_msg == NULL)
err_msg = "Device is currently open";
break;
default:
break;
}
out:
mconsole_reply(req, err_msg, err, 0);
}
struct mconsole_output {
struct list_head list;
struct mc_request *req;
};
static DEFINE_SPINLOCK(client_lock);
static LIST_HEAD(clients);
static char console_buf[MCONSOLE_MAX_DATA];
static int console_index = 0;
static void console_write(struct console *console, const char *string,
unsigned len)
{
struct list_head *ele;
int n;
if(list_empty(&clients))
return;
while(1){
n = min((size_t) len, ARRAY_SIZE(console_buf) - console_index);
strncpy(&console_buf[console_index], string, n);
console_index += n;
string += n;
len -= n;
if(len == 0)
return;
list_for_each(ele, &clients){
struct mconsole_output *entry;
entry = list_entry(ele, struct mconsole_output, list);
mconsole_reply_len(entry->req, console_buf,
console_index, 0, 1);
}
console_index = 0;
}
}
static struct console mc_console = { .name = "mc",
.write = console_write,
.flags = CON_ENABLED,
.index = -1 };
static int mc_add_console(void)
{
register_console(&mc_console);
return 0;
}
late_initcall(mc_add_console);
static void with_console(struct mc_request *req, void (*proc)(void *),
void *arg)
{
struct mconsole_output entry;
unsigned long flags;
entry.req = req;
spin_lock_irqsave(&client_lock, flags);
list_add(&entry.list, &clients);
spin_unlock_irqrestore(&client_lock, flags);
(*proc)(arg);
mconsole_reply_len(req, console_buf, console_index, 0, 0);
console_index = 0;
spin_lock_irqsave(&client_lock, flags);
list_del(&entry.list);
spin_unlock_irqrestore(&client_lock, flags);
}
#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_proc(void *arg)
{
char *op = arg;
handle_sysrq(*op, NULL);
}
void mconsole_sysrq(struct mc_request *req)
{
char *ptr = req->request.data;
ptr += strlen("sysrq");
while(isspace(*ptr)) ptr++;
/* With 'b', the system will shut down without a chance to reply,
* so in this case, we reply first.
*/
if(*ptr == 'b')
mconsole_reply(req, "", 0, 0);
with_console(req, sysrq_proc, ptr);
}
#else
void mconsole_sysrq(struct mc_request *req)
{
mconsole_reply(req, "Sysrq not compiled in", 1, 0);
}
#endif
#ifdef CONFIG_MODE_SKAS
static void stack_proc(void *arg)
{
struct task_struct *from = current, *to = arg;
to->thread.saved_task = from;
switch_to(from, to, from);
}
/* Mconsole stack trace
* Added by Allan Graves, Jeff Dike
* Dumps a stacks registers to the linux console.
* Usage stack <pid>.
*/
static void do_stack_trace(struct mc_request *req)
{
char *ptr = req->request.data;
int pid_requested= -1;
struct task_struct *from = NULL;
struct task_struct *to = NULL;
/* Would be nice:
* 1) Send showregs output to mconsole.
* 2) Add a way to stack dump all pids.
*/
ptr += strlen("stack");
while(isspace(*ptr)) ptr++;
/* Should really check for multiple pids or reject bad args here */
/* What do the arguments in mconsole_reply mean? */
if(sscanf(ptr, "%d", &pid_requested) == 0){
mconsole_reply(req, "Please specify a pid", 1, 0);
return;
}
from = current;
to = find_task_by_pid(pid_requested);
if((to == NULL) || (pid_requested == 0)) {
mconsole_reply(req, "Couldn't find that pid", 1, 0);
return;
}
with_console(req, stack_proc, to);
}
#endif /* CONFIG_MODE_SKAS */
void mconsole_stack(struct mc_request *req)
{
/* This command doesn't work in TT mode, so let's check and then
* get out of here
*/
CHOOSE_MODE(mconsole_reply(req, "Sorry, this doesn't work in TT mode",
1, 0),
do_stack_trace(req));
}
/* Changed by mconsole_setup, which is __setup, and called before SMP is
* active.
*/
static char *notify_socket = NULL;
static int mconsole_init(void)
{
/* long to avoid size mismatch warnings from gcc */
long sock;
int err;
char file[256];
if(umid_file_name("mconsole", file, sizeof(file))) return(-1);
snprintf(mconsole_socket_name, sizeof(file), "%s", file);
sock = os_create_unix_socket(file, sizeof(file), 1);
if (sock < 0){
printk("Failed to initialize management console\n");
return(1);
}
register_reboot_notifier(&reboot_notifier);
err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
"mconsole", (void *)sock);
if (err){
printk("Failed to get IRQ for management console\n");
return(1);
}
if(notify_socket != NULL){
notify_socket = kstrdup(notify_socket, GFP_KERNEL);
if(notify_socket != NULL)
mconsole_notify(notify_socket, MCONSOLE_SOCKET,
mconsole_socket_name,
strlen(mconsole_socket_name) + 1);
else printk(KERN_ERR "mconsole_setup failed to strdup "
"string\n");
}
printk("mconsole (version %d) initialized on %s\n",
MCONSOLE_VERSION, mconsole_socket_name);
return(0);
}
__initcall(mconsole_init);
static int write_proc_mconsole(struct file *file, const char __user *buffer,
unsigned long count, void *data)
{
char *buf;
buf = kmalloc(count + 1, GFP_KERNEL);
if(buf == NULL)
return(-ENOMEM);
if(copy_from_user(buf, buffer, count)){
count = -EFAULT;
goto out;
}
buf[count] = '\0';
mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
out:
kfree(buf);
return(count);
}
static int create_proc_mconsole(void)
{
struct proc_dir_entry *ent;
if(notify_socket == NULL) return(0);
ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
if(ent == NULL){
printk(KERN_INFO "create_proc_mconsole : create_proc_entry failed\n");
return(0);
}
ent->read_proc = NULL;
ent->write_proc = write_proc_mconsole;
return(0);
}
static DEFINE_SPINLOCK(notify_spinlock);
void lock_notify(void)
{
spin_lock(&notify_spinlock);
}
void unlock_notify(void)
{
spin_unlock(&notify_spinlock);
}
__initcall(create_proc_mconsole);
#define NOTIFY "=notify:"
static int mconsole_setup(char *str)
{
if(!strncmp(str, NOTIFY, strlen(NOTIFY))){
str += strlen(NOTIFY);
notify_socket = str;
}
else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
return(1);
}
__setup("mconsole", mconsole_setup);
__uml_help(mconsole_setup,
"mconsole=notify:<socket>\n"
" Requests that the mconsole driver send a message to the named Unix\n"
" socket containing the name of the mconsole socket. This also serves\n"
" to notify outside processes when UML has booted far enough to respond\n"
" to mconsole requests.\n\n"
);
static int notify_panic(struct notifier_block *self, unsigned long unused1,
void *ptr)
{
char *message = ptr;
if(notify_socket == NULL) return(0);
mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
strlen(message) + 1);
return(0);
}
static struct notifier_block panic_exit_notifier = {
.notifier_call = notify_panic,
.next = NULL,
.priority = 1
};
static int add_notifier(void)
{
[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 09:16:30 +00:00
atomic_notifier_chain_register(&panic_notifier_list,
&panic_exit_notifier);
return(0);
}
__initcall(add_notifier);
char *mconsole_notify_socket(void)
{
return(notify_socket);
}
EXPORT_SYMBOL(mconsole_notify_socket);