linux/arch/um/drivers/mconsole_kern.c
Jeff Dike f28169d200 [PATCH] uml: return hotplug errors to host
I noticed that errors happening while hotplugging devices from the host were
never returned back to the mconsole client.  In some cases, success was
returned instead of even an information-free error.

This patch cleans that up by having the low-level configuration code pass back
an error string along with an error code.  At the top level, which knows
whether it is early boot time or responding to an mconsole request, the string
is printk'd or returned to the mconsole client.

There are also whitespace and trivial code cleanups in the surrounding code.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:21 -08:00

942 lines
20 KiB
C

/*
* 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 "user_util.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 "umid.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);
}
/* This list is populated by __initcall routines. */
static LIST_HEAD(mconsole_devices);
void mconsole_register_dev(struct mc_device *new)
{
list_add(&new->list, &mconsole_devices);
}
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 unsigned long long unplugged_pages_count = 0;
static struct list_head unplugged_pages = LIST_HEAD_INIT(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;
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;
}
unplugged->pages[unplug_index++] = addr;
}
unplugged_pages_count++;
}
}
err = 0;
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 = {
.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 -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(console_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;
list_add(&entry.list, &clients);
spin_lock_irqsave(&console_lock, flags);
(*proc)(arg);
mconsole_reply_len(req, console_buf, console_index, 0, 0);
console_index = 0;
spin_unlock_irqrestore(&console_lock, flags);
list_del(&entry.list);
}
#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)
{
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);