drivers/char/sysrq.c

   1 /* -*- linux-c -*-
   2  *
   3  *      $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
   4  *
   5  *      Linux Magic System Request Key Hacks
   6  *
   7  *      (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   8  *      based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/sched.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/mm.h>
  15 #include <linux/fs.h>
  16 #include <linux/mount.h>
  17 #include <linux/kdev_t.h>
  18 #include <linux/major.h>
  19 #include <linux/reboot.h>
  20 #include <linux/sysrq.h>
  21 #include <linux/kbd_kern.h>
  22 #include <linux/quotaops.h>
  23 #include <linux/smp_lock.h>
  24 #include <linux/module.h>
  25
  26 #include <asm/ptrace.h>
  27
  28 extern void wakeup_bdflush(int);
  29 extern void reset_vc(unsigned int);
  30 extern int console_loglevel;
  31 extern struct list_head super_blocks;
  32
  33 /* Whether we react on sysrq keys or just ignore them */
  34 int sysrq_enabled = 1;
  35
  36 /* Machine specific power off function */
  37 void (*sysrq_power_off)(void) = NULL;
  38
  39 EXPORT_SYMBOL(sysrq_power_off);
  40
  41 /* Send a signal to all user processes */
  42
  43 static void send_sig_all(int sig, int even_init)
  44 {
  45         struct task_struct *p;
  46
  47         for_each_task(p) {
  48                 if (p->mm) {                                /* Not swapper nor kernel thread */
  49                         if (p->pid == 1 && even_init)       /* Ugly hack to kill init */
  50                                 p->pid = 0x8000;
  51                         force_sig(sig, p);
  52                 }
  53         }
  54 }
  55
  56 /*
  57  * This function is called by the keyboard handler when SysRq is pressed
  58  * and any other keycode arrives.
  59  */
  60
  61 void handle_sysrq(int key, struct pt_regs *pt_regs,
  62                   struct kbd_struct *kbd, struct tty_struct *tty)
  63 {
  64         int orig_log_level = console_loglevel;
  65
  66         if (!sysrq_enabled)
  67                 return;
  68
  69         if (!key)
  70                 return;
  71
  72         console_loglevel = 7;
  73         printk(KERN_INFO "SysRq: ");
  74         switch (key) {
  75         case 'r':                                           /* R -- Reset raw mode */
  76                 if (kbd) {
  77                         kbd->kbdmode = VC_XLATE;
  78                         printk("Keyboard mode set to XLATE\n");
  79                 }
  80                 break;
  81 #ifdef CONFIG_VT
  82         case 'k':                                           /* K -- SAK */
  83                 printk("SAK\n");
  84                 if (tty)
  85                         do_SAK(tty);
  86                 reset_vc(fg_console);
  87                 break;
  88 #endif
  89         case 'b':                                           /* B -- boot immediately */
  90                 printk("Resetting\n");
  91                 machine_restart(NULL);
  92                 break;
  93         case 'o':                                           /* O -- power off */
  94                 if (sysrq_power_off) {
  95                         printk("Power off\n");
  96                         sysrq_power_off();
  97                 }
  98                 break;
  99         case 's':                                           /* S -- emergency sync */
 100                 printk("Emergency Sync\n");
 101                 emergency_sync_scheduled = EMERG_SYNC;
 102                 wakeup_bdflush(0);
 103                 break;
 104         case 'u':                                           /* U -- emergency remount R/O */
 105                 printk("Emergency Remount R/O\n");
 106                 emergency_sync_scheduled = EMERG_REMOUNT;
 107                 wakeup_bdflush(0);
 108                 break;
 109         case 'p':                                           /* P -- show PC */
 110                 printk("Show Regs\n");
 111                 if (pt_regs)
 112                         show_regs(pt_regs);
 113                 break;
 114         case 't':                                           /* T -- show task info */
 115                 printk("Show State\n");
 116                 show_state();
 117                 break;
 118         case 'm':                                           /* M -- show memory info */
 119                 printk("Show Memory\n");
 120                 show_mem();
 121                 break;
 122         case '0' ... '9':                                   /* 0-9 -- set console logging level */
 123                 orig_log_level = key - '0';
 124                 printk("Log level set to %d\n", orig_log_level);
 125                 break;
 126         case 'e':                                           /* E -- terminate all user processes */
 127                 printk("Terminate All Tasks\n");
 128                 send_sig_all(SIGTERM, 0);
 129                 orig_log_level = 8;                         /* We probably have killed syslogd */
 130                 break;
 131         case 'i':                                           /* I -- kill all user processes */
 132                 printk("Kill All Tasks\n");
 133                 send_sig_all(SIGKILL, 0);
 134                 orig_log_level = 8;
 135                 break;
 136         case 'l':                                           /* L -- kill all processes including init */
 137                 printk("Kill ALL Tasks (even init)\n");
 138                 send_sig_all(SIGKILL, 1);
 139                 orig_log_level = 8;
 140                 break;
 141         default:                                            /* Unknown: help */
 142                 if (kbd)
 143                         printk("unRaw ");
 144 #ifdef CONFIG_VT
 145                 if (tty)
 146                         printk("saK ");
 147 #endif
 148                 printk("Boot ");
 149                 if (sysrq_power_off)
 150                         printk("Off ");
 151                 printk("Sync Unmount showPc showTasks showMem loglevel0-8 tErm kIll killalL\n");
 152                 /* Don't use 'A' as it's handled specially on the Sparc */
 153         }
 154
 155         console_loglevel = orig_log_level;
 156 }
 157
 158 /* Aux routines for the syncer */
 159
 160 static int is_local_disk(kdev_t dev)        /* Guess if the device is a local hard drive */
 161 {
 162         unsigned int major = MAJOR(dev);
 163
 164         switch (major) {
 165         case IDE0_MAJOR:
 166         case IDE1_MAJOR:
 167         case IDE2_MAJOR:
 168         case IDE3_MAJOR:
 169         case SCSI_DISK0_MAJOR:
 170         case SCSI_DISK1_MAJOR:
 171         case SCSI_DISK2_MAJOR:
 172         case SCSI_DISK3_MAJOR:
 173         case SCSI_DISK4_MAJOR:
 174         case SCSI_DISK5_MAJOR:
 175         case SCSI_DISK6_MAJOR:
 176         case SCSI_DISK7_MAJOR:
 177                 return 1;
 178         default:
 179                 return 0;
 180         }
 181 }
 182
 183 static void go_sync(struct super_block *sb, int remount_flag)
 184 {
 185         printk(KERN_INFO "%sing device %s ... ",
 186                remount_flag ? "Remount" : "Sync",
 187                kdevname(sb->s_dev));
 188
 189         if (remount_flag) {                                 /* Remount R/O */
 190                 int ret, flags;
 191                 struct list_head *p;
 192
 193                 if (sb->s_flags & MS_RDONLY) {
 194                         printk("R/O\n");
 195                         return;
 196                 }
 197
 198                 file_list_lock();
 199                 for (p = sb->s_files.next; p != &sb->s_files; p = p->next) {
 200                         struct file *file = list_entry(p, struct file, f_list);
 201                         if (file->f_dentry && file_count(file)
 202                                 && S_ISREG(file->f_dentry->d_inode->i_mode))
 203                                 file->f_mode &= ~2;
 204                 }
 205                 file_list_unlock();
 206                 DQUOT_OFF(sb);
 207                 fsync_dev(sb->s_dev);
 208                 flags = MS_RDONLY;
 209                 if (sb->s_op && sb->s_op->remount_fs) {
 210                         ret = sb->s_op->remount_fs(sb, &flags, NULL);
 211                         if (ret)
 212                                 printk("error %d\n", ret);
 213                         else {
 214                                 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
 215                                 printk("OK\n");
 216                         }
 217                 } else
 218                         printk("nothing to do\n");
 219         } else {
 220                 fsync_dev(sb->s_dev);                       /* Sync only */
 221                 printk("OK\n");
 222         }
 223 }
 224
 225 /*
 226  * Emergency Sync or Unmount. We cannot do it directly, so we set a special
 227  * flag and wake up the bdflush kernel thread which immediately calls this function.
 228  * We process all mounted hard drives first to recover from crashed experimental
 229  * block devices and malfunctional network filesystems.
 230  */
 231
 232 int emergency_sync_scheduled;
 233
 234 void do_emergency_sync(void)
 235 {
 236         struct super_block *sb;
 237         int remount_flag;
 238
 239         lock_kernel();
 240         remount_flag = (emergency_sync_scheduled == EMERG_REMOUNT);
 241         emergency_sync_scheduled = 0;
 242
 243         for (sb = sb_entry(super_blocks.next);
 244              sb != sb_entry(&super_blocks);
 245              sb = sb_entry(sb->s_list.next))
 246                 if (is_local_disk(sb->s_dev))
 247                         go_sync(sb, remount_flag);
 248
 249         for (sb = sb_entry(super_blocks.next);
 250              sb != sb_entry(&super_blocks);
 251              sb = sb_entry(sb->s_list.next))
 252                 if (!is_local_disk(sb->s_dev) && MAJOR(sb->s_dev))
 253                         go_sync(sb, remount_flag);
 254
 255         unlock_kernel();
 256         printk(KERN_INFO "Done.\n");
 257 }