drivers/tty/vt/vt_ioctl.c

   1 /*
   2  *  Copyright (C) 1992 obz under the linux copyright
   3  *
   4  *  Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
   5  *  Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
   6  *  Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
   7  *  Some code moved for less code duplication - Andi Kleen - Mar 1997
   8  *  Check put/get_user, cleanups - acme@conectiva.com.br - Jun 2001
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/errno.h>
  13 #include <linux/sched.h>
  14 #include <linux/tty.h>
  15 #include <linux/timer.h>
  16 #include <linux/kernel.h>
  17 #include <linux/compat.h>
  18 #include <linux/module.h>
  19 #include <linux/kd.h>
  20 #include <linux/vt.h>
  21 #include <linux/string.h>
  22 #include <linux/slab.h>
  23 #include <linux/major.h>
  24 #include <linux/fs.h>
  25 #include <linux/console.h>
  26 #include <linux/consolemap.h>
  27 #include <linux/signal.h>
  28 #include <linux/suspend.h>
  29 #include <linux/timex.h>
  30
  31 #include <asm/io.h>
  32 #include <asm/uaccess.h>
  33
  34 #include <linux/kbd_kern.h>
  35 #include <linux/vt_kern.h>
  36 #include <linux/kbd_diacr.h>
  37 #include <linux/selection.h>
  38
  39 char vt_dont_switch;
  40 extern struct tty_driver *console_driver;
  41
  42 #define VT_IS_IN_USE(i) (console_driver->ttys[i] && console_driver->ttys[i]->count)
  43 #define VT_BUSY(i)      (VT_IS_IN_USE(i) || i == fg_console || vc_cons[i].d == sel_cons)
  44
  45 /*
  46  * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
  47  * experimentation and study of X386 SYSV handling.
  48  *
  49  * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
  50  * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
  51  * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
  52  * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
  53  * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
  54  * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
  55  * to the current console is done by the main ioctl code.
  56  */
  57
  58 #ifdef CONFIG_X86
  59 #include <linux/syscalls.h>
  60 #endif
  61
  62 static void complete_change_console(struct vc_data *vc);
  63
  64 /*
  65  *      User space VT_EVENT handlers
  66  */
  67
  68 struct vt_event_wait {
  69         struct list_head list;
  70         struct vt_event event;
  71         int done;
  72 };
  73
  74 static LIST_HEAD(vt_events);
  75 static DEFINE_SPINLOCK(vt_event_lock);
  76 static DECLARE_WAIT_QUEUE_HEAD(vt_event_waitqueue);
  77
  78 /**
  79  *      vt_event_post
  80  *      @event: the event that occurred
  81  *      @old: old console
  82  *      @new: new console
  83  *
  84  *      Post an VT event to interested VT handlers
  85  */
  86
  87 void vt_event_post(unsigned int event, unsigned int old, unsigned int new)
  88 {
  89         struct list_head *pos, *head;
  90         unsigned long flags;
  91         int wake = 0;
  92
  93         spin_lock_irqsave(&vt_event_lock, flags);
  94         head = &vt_events;
  95
  96         list_for_each(pos, head) {
  97                 struct vt_event_wait *ve = list_entry(pos,
  98                                                 struct vt_event_wait, list);
  99                 if (!(ve->event.event & event))
 100                         continue;
 101                 ve->event.event = event;
 102                 /* kernel view is consoles 0..n-1, user space view is
 103                    console 1..n with 0 meaning current, so we must bias */
 104                 ve->event.oldev = old + 1;
 105                 ve->event.newev = new + 1;
 106                 wake = 1;
 107                 ve->done = 1;
 108         }
 109         spin_unlock_irqrestore(&vt_event_lock, flags);
 110         if (wake)
 111                 wake_up_interruptible(&vt_event_waitqueue);
 112 }
 113
 114 static void __vt_event_queue(struct vt_event_wait *vw)
 115 {
 116         unsigned long flags;
 117         /* Prepare the event */
 118         INIT_LIST_HEAD(&vw->list);
 119         vw->done = 0;
 120         /* Queue our event */
 121         spin_lock_irqsave(&vt_event_lock, flags);
 122         list_add(&vw->list, &vt_events);
 123         spin_unlock_irqrestore(&vt_event_lock, flags);
 124 }
 125
 126 static void __vt_event_wait(struct vt_event_wait *vw)
 127 {
 128         /* Wait for it to pass */
 129         wait_event_interruptible(vt_event_waitqueue, vw->done);
 130 }
 131
 132 static void __vt_event_dequeue(struct vt_event_wait *vw)
 133 {
 134         unsigned long flags;
 135
 136         /* Dequeue it */
 137         spin_lock_irqsave(&vt_event_lock, flags);
 138         list_del(&vw->list);
 139         spin_unlock_irqrestore(&vt_event_lock, flags);
 140 }
 141
 142 /**
 143  *      vt_event_wait           -       wait for an event
 144  *      @vw: our event
 145  *
 146  *      Waits for an event to occur which completes our vt_event_wait
 147  *      structure. On return the structure has wv->done set to 1 for success
 148  *      or 0 if some event such as a signal ended the wait.
 149  */
 150
 151 static void vt_event_wait(struct vt_event_wait *vw)
 152 {
 153         __vt_event_queue(vw);
 154         __vt_event_wait(vw);
 155         __vt_event_dequeue(vw);
 156 }
 157
 158 /**
 159  *      vt_event_wait_ioctl     -       event ioctl handler
 160  *      @arg: argument to ioctl
 161  *
 162  *      Implement the VT_WAITEVENT ioctl using the VT event interface
 163  */
 164
 165 static int vt_event_wait_ioctl(struct vt_event __user *event)
 166 {
 167         struct vt_event_wait vw;
 168
 169         if (copy_from_user(&vw.event, event, sizeof(struct vt_event)))
 170                 return -EFAULT;
 171         /* Highest supported event for now */
 172         if (vw.event.event & ~VT_MAX_EVENT)
 173                 return -EINVAL;
 174
 175         vt_event_wait(&vw);
 176         /* If it occurred report it */
 177         if (vw.done) {
 178                 if (copy_to_user(event, &vw.event, sizeof(struct vt_event)))
 179                         return -EFAULT;
 180                 return 0;
 181         }
 182         return -EINTR;
 183 }
 184
 185 /**
 186  *      vt_waitactive   -       active console wait
 187  *      @event: event code
 188  *      @n: new console
 189  *
 190  *      Helper for event waits. Used to implement the legacy
 191  *      event waiting ioctls in terms of events
 192  */
 193
 194 int vt_waitactive(int n)
 195 {
 196         struct vt_event_wait vw;
 197         do {
 198                 vw.event.event = VT_EVENT_SWITCH;
 199                 __vt_event_queue(&vw);
 200                 if (n == fg_console + 1) {
 201                         __vt_event_dequeue(&vw);
 202                         break;
 203                 }
 204                 __vt_event_wait(&vw);
 205                 __vt_event_dequeue(&vw);
 206                 if (vw.done == 0)
 207                         return -EINTR;
 208         } while (vw.event.newev != n);
 209         return 0;
 210 }
 211
 212 /*
 213  * these are the valid i/o ports we're allowed to change. they map all the
 214  * video ports
 215  */
 216 #define GPFIRST 0x3b4
 217 #define GPLAST 0x3df
 218 #define GPNUM (GPLAST - GPFIRST + 1)
 219
 220
 221
 222 static inline int
 223 do_fontx_ioctl(int cmd, struct consolefontdesc __user *user_cfd, int perm, struct console_font_op *op)
 224 {
 225         struct consolefontdesc cfdarg;
 226         int i;
 227
 228         if (copy_from_user(&cfdarg, user_cfd, sizeof(struct consolefontdesc)))
 229                 return -EFAULT;
 230
 231         switch (cmd) {
 232         case PIO_FONTX:
 233                 if (!perm)
 234                         return -EPERM;
 235                 op->op = KD_FONT_OP_SET;
 236                 op->flags = KD_FONT_FLAG_OLD;
 237                 op->width = 8;
 238                 op->height = cfdarg.charheight;
 239                 op->charcount = cfdarg.charcount;
 240                 op->data = cfdarg.chardata;
 241                 return con_font_op(vc_cons[fg_console].d, op);
 242         case GIO_FONTX: {
 243                 op->op = KD_FONT_OP_GET;
 244                 op->flags = KD_FONT_FLAG_OLD;
 245                 op->width = 8;
 246                 op->height = cfdarg.charheight;
 247                 op->charcount = cfdarg.charcount;
 248                 op->data = cfdarg.chardata;
 249                 i = con_font_op(vc_cons[fg_console].d, op);
 250                 if (i)
 251                         return i;
 252                 cfdarg.charheight = op->height;
 253                 cfdarg.charcount = op->charcount;
 254                 if (copy_to_user(user_cfd, &cfdarg, sizeof(struct consolefontdesc)))
 255                         return -EFAULT;
 256                 return 0;
 257                 }
 258         }
 259         return -EINVAL;
 260 }
 261
 262 static inline int
 263 do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud, int perm, struct vc_data *vc)
 264 {
 265         struct unimapdesc tmp;
 266
 267         if (copy_from_user(&tmp, user_ud, sizeof tmp))
 268                 return -EFAULT;
 269         if (tmp.entries)
 270                 if (!access_ok(VERIFY_WRITE, tmp.entries,
 271                                 tmp.entry_ct*sizeof(struct unipair)))
 272                         return -EFAULT;
 273         switch (cmd) {
 274         case PIO_UNIMAP:
 275                 if (!perm)
 276                         return -EPERM;
 277                 return con_set_unimap(vc, tmp.entry_ct, tmp.entries);
 278         case GIO_UNIMAP:
 279                 if (!perm && fg_console != vc->vc_num)
 280                         return -EPERM;
 281                 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp.entries);
 282         }
 283         return 0;
 284 }
 285
 286
 287
 288 /*
 289  * We handle the console-specific ioctl's here.  We allow the
 290  * capability to modify any console, not just the fg_console.
 291  */
 292 int vt_ioctl(struct tty_struct *tty,
 293              unsigned int cmd, unsigned long arg)
 294 {
 295         struct vc_data *vc = tty->driver_data;
 296         struct console_font_op op;      /* used in multiple places here */
 297         unsigned int console;
 298         unsigned char ucval;
 299         unsigned int uival;
 300         void __user *up = (void __user *)arg;
 301         int i, perm;
 302         int ret = 0;
 303
 304         console = vc->vc_num;
 305
 306
 307         if (!vc_cons_allocated(console)) {      /* impossible? */
 308                 ret = -ENOIOCTLCMD;
 309                 goto out;
 310         }
 311
 312
 313         /*
 314          * To have permissions to do most of the vt ioctls, we either have
 315          * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
 316          */
 317         perm = 0;
 318         if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
 319                 perm = 1;
 320
 321         switch (cmd) {
 322         case TIOCLINUX:
 323                 ret = tioclinux(tty, arg);
 324                 break;
 325         case KIOCSOUND:
 326                 if (!perm)
 327                         return -EPERM;
 328                 /*
 329                  * The use of PIT_TICK_RATE is historic, it used to be
 330                  * the platform-dependent CLOCK_TICK_RATE between 2.6.12
 331                  * and 2.6.36, which was a minor but unfortunate ABI
 332                  * change. kd_mksound is locked by the input layer.
 333                  */
 334                 if (arg)
 335                         arg = PIT_TICK_RATE / arg;
 336                 kd_mksound(arg, 0);
 337                 break;
 338
 339         case KDMKTONE:
 340                 if (!perm)
 341                         return -EPERM;
 342         {
 343                 unsigned int ticks, count;
 344
 345                 /*
 346                  * Generate the tone for the appropriate number of ticks.
 347                  * If the time is zero, turn off sound ourselves.
 348                  */
 349                 ticks = HZ * ((arg >> 16) & 0xffff) / 1000;
 350                 count = ticks ? (arg & 0xffff) : 0;
 351                 if (count)
 352                         count = PIT_TICK_RATE / count;
 353                 kd_mksound(count, ticks);
 354                 break;
 355         }
 356
 357         case KDGKBTYPE:
 358                 /*
 359                  * this is naïve.
 360                  */
 361                 ucval = KB_101;
 362                 ret = put_user(ucval, (char __user *)arg);
 363                 break;
 364
 365                 /*
 366                  * These cannot be implemented on any machine that implements
 367                  * ioperm() in user level (such as Alpha PCs) or not at all.
 368                  *
 369                  * XXX: you should never use these, just call ioperm directly..
 370                  */
 371 #ifdef CONFIG_X86
 372         case KDADDIO:
 373         case KDDELIO:
 374                 /*
 375                  * KDADDIO and KDDELIO may be able to add ports beyond what
 376                  * we reject here, but to be safe...
 377                  *
 378                  * These are locked internally via sys_ioperm
 379                  */
 380                 if (arg < GPFIRST || arg > GPLAST) {
 381                         ret = -EINVAL;
 382                         break;
 383                 }
 384                 ret = sys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;
 385                 break;
 386
 387         case KDENABIO:
 388         case KDDISABIO:
 389                 ret = sys_ioperm(GPFIRST, GPNUM,
 390                                   (cmd == KDENABIO)) ? -ENXIO : 0;
 391                 break;
 392 #endif
 393
 394         /* Linux m68k/i386 interface for setting the keyboard delay/repeat rate */
 395
 396         case KDKBDREP:
 397         {
 398                 struct kbd_repeat kbrep;
 399
 400                 if (!capable(CAP_SYS_TTY_CONFIG))
 401                         return -EPERM;
 402
 403                 if (copy_from_user(&kbrep, up, sizeof(struct kbd_repeat))) {
 404                         ret =  -EFAULT;
 405                         break;
 406                 }
 407                 ret = kbd_rate(&kbrep);
 408                 if (ret)
 409                         break;
 410                 if (copy_to_user(up, &kbrep, sizeof(struct kbd_repeat)))
 411                         ret = -EFAULT;
 412                 break;
 413         }
 414
 415         case KDSETMODE:
 416                 /*
 417                  * currently, setting the mode from KD_TEXT to KD_GRAPHICS
 418                  * doesn't do a whole lot. i'm not sure if it should do any
 419                  * restoration of modes or what...
 420                  *
 421                  * XXX It should at least call into the driver, fbdev's definitely
 422                  * need to restore their engine state. --BenH
 423                  */
 424                 if (!perm)
 425                         return -EPERM;
 426                 switch (arg) {
 427                 case KD_GRAPHICS:
 428                         break;
 429                 case KD_TEXT0:
 430                 case KD_TEXT1:
 431                         arg = KD_TEXT;
 432                 case KD_TEXT:
 433                         break;
 434                 default:
 435                         ret = -EINVAL;
 436                         goto out;
 437                 }
 438                 /* FIXME: this needs the console lock extending */
 439                 if (vc->vc_mode == (unsigned char) arg)
 440                         break;
 441                 vc->vc_mode = (unsigned char) arg;
 442                 if (console != fg_console)
 443                         break;
 444                 /*
 445                  * explicitly blank/unblank the screen if switching modes
 446                  */
 447                 console_lock();
 448                 if (arg == KD_TEXT)
 449                         do_unblank_screen(1);
 450                 else
 451                         do_blank_screen(1);
 452                 console_unlock();
 453                 break;
 454
 455         case KDGETMODE:
 456                 uival = vc->vc_mode;
 457                 goto setint;
 458
 459         case KDMAPDISP:
 460         case KDUNMAPDISP:
 461                 /*
 462                  * these work like a combination of mmap and KDENABIO.
 463                  * this could be easily finished.
 464                  */
 465                 ret = -EINVAL;
 466                 break;
 467
 468         case KDSKBMODE:
 469                 if (!perm)
 470                         return -EPERM;
 471                 ret = vt_do_kdskbmode(console, arg);
 472                 if (ret == 0)
 473                         tty_ldisc_flush(tty);
 474                 break;
 475
 476         case KDGKBMODE:
 477                 uival = vt_do_kdgkbmode(console);
 478                 ret = put_user(uival, (int __user *)arg);
 479                 break;
 480
 481         /* this could be folded into KDSKBMODE, but for compatibility
 482            reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
 483         case KDSKBMETA:
 484                 ret = vt_do_kdskbmeta(console, arg);
 485                 break;
 486
 487         case KDGKBMETA:
 488                 /* FIXME: should review whether this is worth locking */
 489                 uival = vt_do_kdgkbmeta(console);
 490         setint:
 491                 ret = put_user(uival, (int __user *)arg);
 492                 break;
 493
 494         case KDGETKEYCODE:
 495         case KDSETKEYCODE:
 496                 if(!capable(CAP_SYS_TTY_CONFIG))
 497                         perm = 0;
 498                 ret = vt_do_kbkeycode_ioctl(cmd, up, perm);
 499                 break;
 500
 501         case KDGKBENT:
 502         case KDSKBENT:
 503                 ret = vt_do_kdsk_ioctl(cmd, up, perm, console);
 504                 break;
 505
 506         case KDGKBSENT:
 507         case KDSKBSENT:
 508                 ret = vt_do_kdgkb_ioctl(cmd, up, perm);
 509                 break;
 510
 511         /* Diacritical processing. Handled in keyboard.c as it has
 512            to operate on the keyboard locks and structures */
 513         case KDGKBDIACR:
 514         case KDGKBDIACRUC:
 515         case KDSKBDIACR:
 516         case KDSKBDIACRUC:
 517                 ret = vt_do_diacrit(cmd, up, perm);
 518                 break;
 519
 520         /* the ioctls below read/set the flags usually shown in the leds */
 521         /* don't use them - they will go away without warning */
 522         case KDGKBLED:
 523         case KDSKBLED:
 524         case KDGETLED:
 525         case KDSETLED:
 526                 ret = vt_do_kdskled(console, cmd, arg, perm);
 527                 break;
 528
 529         /*
 530          * A process can indicate its willingness to accept signals
 531          * generated by pressing an appropriate key combination.
 532          * Thus, one can have a daemon that e.g. spawns a new console
 533          * upon a keypress and then changes to it.
 534          * See also the kbrequest field of inittab(5).
 535          */
 536         case KDSIGACCEPT:
 537         {
 538                 if (!perm || !capable(CAP_KILL))
 539                         return -EPERM;
 540                 if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
 541                         ret = -EINVAL;
 542                 else {
 543                         spin_lock_irq(&vt_spawn_con.lock);
 544                         put_pid(vt_spawn_con.pid);
 545                         vt_spawn_con.pid = get_pid(task_pid(current));
 546                         vt_spawn_con.sig = arg;
 547                         spin_unlock_irq(&vt_spawn_con.lock);
 548                 }
 549                 break;
 550         }
 551
 552         case VT_SETMODE:
 553         {
 554                 struct vt_mode tmp;
 555
 556                 if (!perm)
 557                         return -EPERM;
 558                 if (copy_from_user(&tmp, up, sizeof(struct vt_mode))) {
 559                         ret = -EFAULT;
 560                         goto out;
 561                 }
 562                 if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS) {
 563                         ret = -EINVAL;
 564                         goto out;
 565                 }
 566                 console_lock();
 567                 vc->vt_mode = tmp;
 568                 /* the frsig is ignored, so we set it to 0 */
 569                 vc->vt_mode.frsig = 0;
 570                 put_pid(vc->vt_pid);
 571                 vc->vt_pid = get_pid(task_pid(current));
 572                 /* no switch is required -- saw@shade.msu.ru */
 573                 vc->vt_newvt = -1;
 574                 console_unlock();
 575                 break;
 576         }
 577
 578         case VT_GETMODE:
 579         {
 580                 struct vt_mode tmp;
 581                 int rc;
 582
 583                 console_lock();
 584                 memcpy(&tmp, &vc->vt_mode, sizeof(struct vt_mode));
 585                 console_unlock();
 586
 587                 rc = copy_to_user(up, &tmp, sizeof(struct vt_mode));
 588                 if (rc)
 589                         ret = -EFAULT;
 590                 break;
 591         }
 592
 593         /*
 594          * Returns global vt state. Note that VT 0 is always open, since
 595          * it's an alias for the current VT, and people can't use it here.
 596          * We cannot return state for more than 16 VTs, since v_state is short.
 597          */
 598         case VT_GETSTATE:
 599         {
 600                 struct vt_stat __user *vtstat = up;
 601                 unsigned short state, mask;
 602
 603                 /* Review: FIXME: Console lock ? */
 604                 if (put_user(fg_console + 1, &vtstat->v_active))
 605                         ret = -EFAULT;
 606                 else {
 607                         state = 1;      /* /dev/tty0 is always open */
 608                         for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask;
 609                                                         ++i, mask <<= 1)
 610                                 if (VT_IS_IN_USE(i))
 611                                         state |= mask;
 612                         ret = put_user(state, &vtstat->v_state);
 613                 }
 614                 break;
 615         }
 616
 617         /*
 618          * Returns the first available (non-opened) console.
 619          */
 620         case VT_OPENQRY:
 621                 /* FIXME: locking ? - but then this is a stupid API */
 622                 for (i = 0; i < MAX_NR_CONSOLES; ++i)
 623                         if (! VT_IS_IN_USE(i))
 624                                 break;
 625                 uival = i < MAX_NR_CONSOLES ? (i+1) : -1;
 626                 goto setint;
 627
 628         /*
 629          * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
 630          * with num >= 1 (switches to vt 0, our console, are not allowed, just
 631          * to preserve sanity).
 632          */
 633         case VT_ACTIVATE:
 634                 if (!perm)
 635                         return -EPERM;
 636                 if (arg == 0 || arg > MAX_NR_CONSOLES)
 637                         ret =  -ENXIO;
 638                 else {
 639                         arg--;
 640                         console_lock();
 641                         ret = vc_allocate(arg);
 642                         console_unlock();
 643                         if (ret)
 644                                 break;
 645                         set_console(arg);
 646                 }
 647                 break;
 648
 649         case VT_SETACTIVATE:
 650         {
 651                 struct vt_setactivate vsa;
 652
 653                 if (!perm)
 654                         return -EPERM;
 655
 656                 if (copy_from_user(&vsa, (struct vt_setactivate __user *)arg,
 657                                         sizeof(struct vt_setactivate))) {
 658                         ret = -EFAULT;
 659                         goto out;
 660                 }
 661                 if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
 662                         ret = -ENXIO;
 663                 else {
 664                         vsa.console--;
 665                         console_lock();
 666                         ret = vc_allocate(vsa.console);
 667                         if (ret == 0) {
 668                                 struct vc_data *nvc;
 669                                 /* This is safe providing we don't drop the
 670                                    console sem between vc_allocate and
 671                                    finishing referencing nvc */
 672                                 nvc = vc_cons[vsa.console].d;
 673                                 nvc->vt_mode = vsa.mode;
 674                                 nvc->vt_mode.frsig = 0;
 675                                 put_pid(nvc->vt_pid);
 676                                 nvc->vt_pid = get_pid(task_pid(current));
 677                         }
 678                         console_unlock();
 679                         if (ret)
 680                                 break;
 681                         /* Commence switch and lock */
 682                         /* Review set_console locks */
 683                         set_console(vsa.console);
 684                 }
 685                 break;
 686         }
 687
 688         /*
 689          * wait until the specified VT has been activated
 690          */
 691         case VT_WAITACTIVE:
 692                 if (!perm)
 693                         return -EPERM;
 694                 if (arg == 0 || arg > MAX_NR_CONSOLES)
 695                         ret = -ENXIO;
 696                 else
 697                         ret = vt_waitactive(arg);
 698                 break;
 699
 700         /*
 701          * If a vt is under process control, the kernel will not switch to it
 702          * immediately, but postpone the operation until the process calls this
 703          * ioctl, allowing the switch to complete.
 704          *
 705          * According to the X sources this is the behavior:
 706          *      0:      pending switch-from not OK
 707          *      1:      pending switch-from OK
 708          *      2:      completed switch-to OK
 709          */
 710         case VT_RELDISP:
 711                 if (!perm)
 712                         return -EPERM;
 713
 714                 console_lock();
 715                 if (vc->vt_mode.mode != VT_PROCESS) {
 716                         console_unlock();
 717                         ret = -EINVAL;
 718                         break;
 719                 }
 720                 /*
 721                  * Switching-from response
 722                  */
 723                 if (vc->vt_newvt >= 0) {
 724                         if (arg == 0)
 725                                 /*
 726                                  * Switch disallowed, so forget we were trying
 727                                  * to do it.
 728                                  */
 729                                 vc->vt_newvt = -1;
 730
 731                         else {
 732                                 /*
 733                                  * The current vt has been released, so
 734                                  * complete the switch.
 735                                  */
 736                                 int newvt;
 737                                 newvt = vc->vt_newvt;
 738                                 vc->vt_newvt = -1;
 739                                 ret = vc_allocate(newvt);
 740                                 if (ret) {
 741                                         console_unlock();
 742                                         break;
 743                                 }
 744                                 /*
 745                                  * When we actually do the console switch,
 746                                  * make sure we are atomic with respect to
 747                                  * other console switches..
 748                                  */
 749                                 complete_change_console(vc_cons[newvt].d);
 750                         }
 751                 } else {
 752                         /*
 753                          * Switched-to response
 754                          */
 755                         /*
 756                          * If it's just an ACK, ignore it
 757                          */
 758                         if (arg != VT_ACKACQ)
 759                                 ret = -EINVAL;
 760                 }
 761                 console_unlock();
 762                 break;
 763
 764          /*
 765           * Disallocate memory associated to VT (but leave VT1)
 766           */
 767          case VT_DISALLOCATE:
 768                 if (arg > MAX_NR_CONSOLES) {
 769                         ret = -ENXIO;
 770                         break;
 771                 }
 772                 if (arg == 0) {
 773                     /* deallocate all unused consoles, but leave 0 */
 774                         console_lock();
 775                         for (i=1; i<MAX_NR_CONSOLES; i++)
 776                                 if (! VT_BUSY(i))
 777                                         vc_deallocate(i);
 778                         console_unlock();
 779                 } else {
 780                         /* deallocate a single console, if possible */
 781                         arg--;
 782                         if (VT_BUSY(arg))
 783                                 ret = -EBUSY;
 784                         else if (arg) {                       /* leave 0 */
 785                                 console_lock();
 786                                 vc_deallocate(arg);
 787                                 console_unlock();
 788                         }
 789                 }
 790                 break;
 791
 792         case VT_RESIZE:
 793         {
 794                 struct vt_sizes __user *vtsizes = up;
 795                 struct vc_data *vc;
 796
 797                 ushort ll,cc;
 798                 if (!perm)
 799                         return -EPERM;
 800                 if (get_user(ll, &vtsizes->v_rows) ||
 801                     get_user(cc, &vtsizes->v_cols))
 802                         ret = -EFAULT;
 803                 else {
 804                         console_lock();
 805                         for (i = 0; i < MAX_NR_CONSOLES; i++) {
 806                                 vc = vc_cons[i].d;
 807
 808                                 if (vc) {
 809                                         vc->vc_resize_user = 1;
 810                                         /* FIXME: review v tty lock */
 811                                         vc_resize(vc_cons[i].d, cc, ll);
 812                                 }
 813                         }
 814                         console_unlock();
 815                 }
 816                 break;
 817         }
 818
 819         case VT_RESIZEX:
 820         {
 821                 struct vt_consize __user *vtconsize = up;
 822                 ushort ll,cc,vlin,clin,vcol,ccol;
 823                 if (!perm)
 824                         return -EPERM;
 825                 if (!access_ok(VERIFY_READ, vtconsize,
 826                                 sizeof(struct vt_consize))) {
 827                         ret = -EFAULT;
 828                         break;
 829                 }
 830                 /* FIXME: Should check the copies properly */
 831                 __get_user(ll, &vtconsize->v_rows);
 832                 __get_user(cc, &vtconsize->v_cols);
 833                 __get_user(vlin, &vtconsize->v_vlin);
 834                 __get_user(clin, &vtconsize->v_clin);
 835                 __get_user(vcol, &vtconsize->v_vcol);
 836                 __get_user(ccol, &vtconsize->v_ccol);
 837                 vlin = vlin ? vlin : vc->vc_scan_lines;
 838                 if (clin) {
 839                         if (ll) {
 840                                 if (ll != vlin/clin) {
 841                                         /* Parameters don't add up */
 842                                         ret = -EINVAL;
 843                                         break;
 844                                 }
 845                         } else
 846                                 ll = vlin/clin;
 847                 }
 848                 if (vcol && ccol) {
 849                         if (cc) {
 850                                 if (cc != vcol/ccol) {
 851                                         ret = -EINVAL;
 852                                         break;
 853                                 }
 854                         } else
 855                                 cc = vcol/ccol;
 856                 }
 857
 858                 if (clin > 32) {
 859                         ret =  -EINVAL;
 860                         break;
 861                 }
 862
 863                 for (i = 0; i < MAX_NR_CONSOLES; i++) {
 864                         if (!vc_cons[i].d)
 865                                 continue;
 866                         console_lock();
 867                         if (vlin)
 868                                 vc_cons[i].d->vc_scan_lines = vlin;
 869                         if (clin)
 870                                 vc_cons[i].d->vc_font.height = clin;
 871                         vc_cons[i].d->vc_resize_user = 1;
 872                         vc_resize(vc_cons[i].d, cc, ll);
 873                         console_unlock();
 874                 }
 875                 break;
 876         }
 877
 878         case PIO_FONT: {
 879                 if (!perm)
 880                         return -EPERM;
 881                 op.op = KD_FONT_OP_SET;
 882                 op.flags = KD_FONT_FLAG_OLD | KD_FONT_FLAG_DONT_RECALC; /* Compatibility */
 883                 op.width = 8;
 884                 op.height = 0;
 885                 op.charcount = 256;
 886                 op.data = up;
 887                 ret = con_font_op(vc_cons[fg_console].d, &op);
 888                 break;
 889         }
 890
 891         case GIO_FONT: {
 892                 op.op = KD_FONT_OP_GET;
 893                 op.flags = KD_FONT_FLAG_OLD;
 894                 op.width = 8;
 895                 op.height = 32;
 896                 op.charcount = 256;
 897                 op.data = up;
 898                 ret = con_font_op(vc_cons[fg_console].d, &op);
 899                 break;
 900         }
 901
 902         case PIO_CMAP:
 903                 if (!perm)
 904                         ret = -EPERM;
 905                 else
 906                         ret = con_set_cmap(up);
 907                 break;
 908
 909         case GIO_CMAP:
 910                 ret = con_get_cmap(up);
 911                 break;
 912
 913         case PIO_FONTX:
 914         case GIO_FONTX:
 915                 ret = do_fontx_ioctl(cmd, up, perm, &op);
 916                 break;
 917
 918         case PIO_FONTRESET:
 919         {
 920                 if (!perm)
 921                         return -EPERM;
 922
 923 #ifdef BROKEN_GRAPHICS_PROGRAMS
 924                 /* With BROKEN_GRAPHICS_PROGRAMS defined, the default
 925                    font is not saved. */
 926                 ret = -ENOSYS;
 927                 break;
 928 #else
 929                 {
 930                 op.op = KD_FONT_OP_SET_DEFAULT;
 931                 op.data = NULL;
 932                 ret = con_font_op(vc_cons[fg_console].d, &op);
 933                 if (ret)
 934                         break;
 935                 console_lock();
 936                 con_set_default_unimap(vc_cons[fg_console].d);
 937                 console_unlock();
 938                 break;
 939                 }
 940 #endif
 941         }
 942
 943         case KDFONTOP: {
 944                 if (copy_from_user(&op, up, sizeof(op))) {
 945                         ret = -EFAULT;
 946                         break;
 947                 }
 948                 if (!perm && op.op != KD_FONT_OP_GET)
 949                         return -EPERM;
 950                 ret = con_font_op(vc, &op);
 951                 if (ret)
 952                         break;
 953                 if (copy_to_user(up, &op, sizeof(op)))
 954                         ret = -EFAULT;
 955                 break;
 956         }
 957
 958         case PIO_SCRNMAP:
 959                 if (!perm)
 960                         ret = -EPERM;
 961                 else
 962                         ret = con_set_trans_old(up);
 963                 break;
 964
 965         case GIO_SCRNMAP:
 966                 ret = con_get_trans_old(up);
 967                 break;
 968
 969         case PIO_UNISCRNMAP:
 970                 if (!perm)
 971                         ret = -EPERM;
 972                 else
 973                         ret = con_set_trans_new(up);
 974                 break;
 975
 976         case GIO_UNISCRNMAP:
 977                 ret = con_get_trans_new(up);
 978                 break;
 979
 980         case PIO_UNIMAPCLR:
 981               { struct unimapinit ui;
 982                 if (!perm)
 983                         return -EPERM;
 984                 ret = copy_from_user(&ui, up, sizeof(struct unimapinit));
 985                 if (ret)
 986                         ret = -EFAULT;
 987                 else
 988                         con_clear_unimap(vc, &ui);
 989                 break;
 990               }
 991
 992         case PIO_UNIMAP:
 993         case GIO_UNIMAP:
 994                 ret = do_unimap_ioctl(cmd, up, perm, vc);
 995                 break;
 996
 997         case VT_LOCKSWITCH:
 998                 if (!capable(CAP_SYS_TTY_CONFIG))
 999                         return -EPERM;
1000                 vt_dont_switch = 1;
1001                 break;
1002         case VT_UNLOCKSWITCH:
1003                 if (!capable(CAP_SYS_TTY_CONFIG))
1004                         return -EPERM;
1005                 vt_dont_switch = 0;
1006                 break;
1007         case VT_GETHIFONTMASK:
1008                 ret = put_user(vc->vc_hi_font_mask,
1009                                         (unsigned short __user *)arg);
1010                 break;
1011         case VT_WAITEVENT:
1012                 ret = vt_event_wait_ioctl((struct vt_event __user *)arg);
1013                 break;
1014         default:
1015                 ret = -ENOIOCTLCMD;
1016         }
1017 out:
1018         return ret;
1019 }
1020
1021 void reset_vc(struct vc_data *vc)
1022 {
1023         vc->vc_mode = KD_TEXT;
1024         vt_reset_unicode(vc->vc_num);
1025         vc->vt_mode.mode = VT_AUTO;
1026         vc->vt_mode.waitv = 0;
1027         vc->vt_mode.relsig = 0;
1028         vc->vt_mode.acqsig = 0;
1029         vc->vt_mode.frsig = 0;
1030         put_pid(vc->vt_pid);
1031         vc->vt_pid = NULL;
1032         vc->vt_newvt = -1;
1033         if (!in_interrupt())    /* Via keyboard.c:SAK() - akpm */
1034                 reset_palette(vc);
1035 }
1036
1037 void vc_SAK(struct work_struct *work)
1038 {
1039         struct vc *vc_con =
1040                 container_of(work, struct vc, SAK_work);
1041         struct vc_data *vc;
1042         struct tty_struct *tty;
1043
1044         console_lock();
1045         vc = vc_con->d;
1046         if (vc) {
1047                 /* FIXME: review tty ref counting */
1048                 tty = vc->port.tty;
1049                 /*
1050                  * SAK should also work in all raw modes and reset
1051                  * them properly.
1052                  */
1053                 if (tty)
1054                         __do_SAK(tty);
1055                 reset_vc(vc);
1056         }
1057         console_unlock();
1058 }
1059
1060 #ifdef CONFIG_COMPAT
1061
1062 struct compat_consolefontdesc {
1063         unsigned short charcount;       /* characters in font (256 or 512) */
1064         unsigned short charheight;      /* scan lines per character (1-32) */
1065         compat_caddr_t chardata;        /* font data in expanded form */
1066 };
1067
1068 static inline int
1069 compat_fontx_ioctl(int cmd, struct compat_consolefontdesc __user *user_cfd,
1070                          int perm, struct console_font_op *op)
1071 {
1072         struct compat_consolefontdesc cfdarg;
1073         int i;
1074
1075         if (copy_from_user(&cfdarg, user_cfd, sizeof(struct compat_consolefontdesc)))
1076                 return -EFAULT;
1077
1078         switch (cmd) {
1079         case PIO_FONTX:
1080                 if (!perm)
1081                         return -EPERM;
1082                 op->op = KD_FONT_OP_SET;
1083                 op->flags = KD_FONT_FLAG_OLD;
1084                 op->width = 8;
1085                 op->height = cfdarg.charheight;
1086                 op->charcount = cfdarg.charcount;
1087                 op->data = compat_ptr(cfdarg.chardata);
1088                 return con_font_op(vc_cons[fg_console].d, op);
1089         case GIO_FONTX:
1090                 op->op = KD_FONT_OP_GET;
1091                 op->flags = KD_FONT_FLAG_OLD;
1092                 op->width = 8;
1093                 op->height = cfdarg.charheight;
1094                 op->charcount = cfdarg.charcount;
1095                 op->data = compat_ptr(cfdarg.chardata);
1096                 i = con_font_op(vc_cons[fg_console].d, op);
1097                 if (i)
1098                         return i;
1099                 cfdarg.charheight = op->height;
1100                 cfdarg.charcount = op->charcount;
1101                 if (copy_to_user(user_cfd, &cfdarg, sizeof(struct compat_consolefontdesc)))
1102                         return -EFAULT;
1103                 return 0;
1104         }
1105         return -EINVAL;
1106 }
1107
1108 struct compat_console_font_op {
1109         compat_uint_t op;        /* operation code KD_FONT_OP_* */
1110         compat_uint_t flags;     /* KD_FONT_FLAG_* */
1111         compat_uint_t width, height;     /* font size */
1112         compat_uint_t charcount;
1113         compat_caddr_t data;    /* font data with height fixed to 32 */
1114 };
1115
1116 static inline int
1117 compat_kdfontop_ioctl(struct compat_console_font_op __user *fontop,
1118                          int perm, struct console_font_op *op, struct vc_data *vc)
1119 {
1120         int i;
1121
1122         if (copy_from_user(op, fontop, sizeof(struct compat_console_font_op)))
1123                 return -EFAULT;
1124         if (!perm && op->op != KD_FONT_OP_GET)
1125                 return -EPERM;
1126         op->data = compat_ptr(((struct compat_console_font_op *)op)->data);
1127         i = con_font_op(vc, op);
1128         if (i)
1129                 return i;
1130         ((struct compat_console_font_op *)op)->data = (unsigned long)op->data;
1131         if (copy_to_user(fontop, op, sizeof(struct compat_console_font_op)))
1132                 return -EFAULT;
1133         return 0;
1134 }
1135
1136 struct compat_unimapdesc {
1137         unsigned short entry_ct;
1138         compat_caddr_t entries;
1139 };
1140
1141 static inline int
1142 compat_unimap_ioctl(unsigned int cmd, struct compat_unimapdesc __user *user_ud,
1143                          int perm, struct vc_data *vc)
1144 {
1145         struct compat_unimapdesc tmp;
1146         struct unipair __user *tmp_entries;
1147
1148         if (copy_from_user(&tmp, user_ud, sizeof tmp))
1149                 return -EFAULT;
1150         tmp_entries = compat_ptr(tmp.entries);
1151         if (tmp_entries)
1152                 if (!access_ok(VERIFY_WRITE, tmp_entries,
1153                                 tmp.entry_ct*sizeof(struct unipair)))
1154                         return -EFAULT;
1155         switch (cmd) {
1156         case PIO_UNIMAP:
1157                 if (!perm)
1158                         return -EPERM;
1159                 return con_set_unimap(vc, tmp.entry_ct, tmp_entries);
1160         case GIO_UNIMAP:
1161                 if (!perm && fg_console != vc->vc_num)
1162                         return -EPERM;
1163                 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp_entries);
1164         }
1165         return 0;
1166 }
1167
1168 long vt_compat_ioctl(struct tty_struct *tty,
1169              unsigned int cmd, unsigned long arg)
1170 {
1171         struct vc_data *vc = tty->driver_data;
1172         struct console_font_op op;      /* used in multiple places here */
1173         unsigned int console;
1174         void __user *up = (void __user *)arg;
1175         int perm;
1176         int ret = 0;
1177
1178         console = vc->vc_num;
1179
1180         if (!vc_cons_allocated(console)) {      /* impossible? */
1181                 ret = -ENOIOCTLCMD;
1182                 goto out;
1183         }
1184
1185         /*
1186          * To have permissions to do most of the vt ioctls, we either have
1187          * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
1188          */
1189         perm = 0;
1190         if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
1191                 perm = 1;
1192
1193         switch (cmd) {
1194         /*
1195          * these need special handlers for incompatible data structures
1196          */
1197         case PIO_FONTX:
1198         case GIO_FONTX:
1199                 ret = compat_fontx_ioctl(cmd, up, perm, &op);
1200                 break;
1201
1202         case KDFONTOP:
1203                 ret = compat_kdfontop_ioctl(up, perm, &op, vc);
1204                 break;
1205
1206         case PIO_UNIMAP:
1207         case GIO_UNIMAP:
1208                 ret = compat_unimap_ioctl(cmd, up, perm, vc);
1209                 break;
1210
1211         /*
1212          * all these treat 'arg' as an integer
1213          */
1214         case KIOCSOUND:
1215         case KDMKTONE:
1216 #ifdef CONFIG_X86
1217         case KDADDIO:
1218         case KDDELIO:
1219 #endif
1220         case KDSETMODE:
1221         case KDMAPDISP:
1222         case KDUNMAPDISP:
1223         case KDSKBMODE:
1224         case KDSKBMETA:
1225         case KDSKBLED:
1226         case KDSETLED:
1227         case KDSIGACCEPT:
1228         case VT_ACTIVATE:
1229         case VT_WAITACTIVE:
1230         case VT_RELDISP:
1231         case VT_DISALLOCATE:
1232         case VT_RESIZE:
1233         case VT_RESIZEX:
1234                 goto fallback;
1235
1236         /*
1237          * the rest has a compatible data structure behind arg,
1238          * but we have to convert it to a proper 64 bit pointer.
1239          */
1240         default:
1241                 arg = (unsigned long)compat_ptr(arg);
1242                 goto fallback;
1243         }
1244 out:
1245         return ret;
1246
1247 fallback:
1248         return vt_ioctl(tty, cmd, arg);
1249 }
1250
1251
1252 #endif /* CONFIG_COMPAT */
1253
1254
1255 /*
1256  * Performs the back end of a vt switch. Called under the console
1257  * semaphore.
1258  */
1259 static void complete_change_console(struct vc_data *vc)
1260 {
1261         unsigned char old_vc_mode;
1262         int old = fg_console;
1263
1264         last_console = fg_console;
1265
1266         /*
1267          * If we're switching, we could be going from KD_GRAPHICS to
1268          * KD_TEXT mode or vice versa, which means we need to blank or
1269          * unblank the screen later.
1270          */
1271         old_vc_mode = vc_cons[fg_console].d->vc_mode;
1272         switch_screen(vc);
1273
1274         /*
1275          * This can't appear below a successful kill_pid().  If it did,
1276          * then the *blank_screen operation could occur while X, having
1277          * received acqsig, is waking up on another processor.  This
1278          * condition can lead to overlapping accesses to the VGA range
1279          * and the framebuffer (causing system lockups).
1280          *
1281          * To account for this we duplicate this code below only if the
1282          * controlling process is gone and we've called reset_vc.
1283          */
1284         if (old_vc_mode != vc->vc_mode) {
1285                 if (vc->vc_mode == KD_TEXT)
1286                         do_unblank_screen(1);
1287                 else
1288                         do_blank_screen(1);
1289         }
1290
1291         /*
1292          * If this new console is under process control, send it a signal
1293          * telling it that it has acquired. Also check if it has died and
1294          * clean up (similar to logic employed in change_console())
1295          */
1296         if (vc->vt_mode.mode == VT_PROCESS) {
1297                 /*
1298                  * Send the signal as privileged - kill_pid() will
1299                  * tell us if the process has gone or something else
1300                  * is awry
1301                  */
1302                 if (kill_pid(vc->vt_pid, vc->vt_mode.acqsig, 1) != 0) {
1303                 /*
1304                  * The controlling process has died, so we revert back to
1305                  * normal operation. In this case, we'll also change back
1306                  * to KD_TEXT mode. I'm not sure if this is strictly correct
1307                  * but it saves the agony when the X server dies and the screen
1308                  * remains blanked due to KD_GRAPHICS! It would be nice to do
1309                  * this outside of VT_PROCESS but there is no single process
1310                  * to account for and tracking tty count may be undesirable.
1311                  */
1312                         reset_vc(vc);
1313
1314                         if (old_vc_mode != vc->vc_mode) {
1315                                 if (vc->vc_mode == KD_TEXT)
1316                                         do_unblank_screen(1);
1317                                 else
1318                                         do_blank_screen(1);
1319                         }
1320                 }
1321         }
1322
1323         /*
1324          * Wake anyone waiting for their VT to activate
1325          */
1326         vt_event_post(VT_EVENT_SWITCH, old, vc->vc_num);
1327         return;
1328 }
1329
1330 /*
1331  * Performs the front-end of a vt switch
1332  */
1333 void change_console(struct vc_data *new_vc)
1334 {
1335         struct vc_data *vc;
1336
1337         if (!new_vc || new_vc->vc_num == fg_console || vt_dont_switch)
1338                 return;
1339
1340         /*
1341          * If this vt is in process mode, then we need to handshake with
1342          * that process before switching. Essentially, we store where that
1343          * vt wants to switch to and wait for it to tell us when it's done
1344          * (via VT_RELDISP ioctl).
1345          *
1346          * We also check to see if the controlling process still exists.
1347          * If it doesn't, we reset this vt to auto mode and continue.
1348          * This is a cheap way to track process control. The worst thing
1349          * that can happen is: we send a signal to a process, it dies, and
1350          * the switch gets "lost" waiting for a response; hopefully, the
1351          * user will try again, we'll detect the process is gone (unless
1352          * the user waits just the right amount of time :-) and revert the
1353          * vt to auto control.
1354          */
1355         vc = vc_cons[fg_console].d;
1356         if (vc->vt_mode.mode == VT_PROCESS) {
1357                 /*
1358                  * Send the signal as privileged - kill_pid() will
1359                  * tell us if the process has gone or something else
1360                  * is awry.
1361                  *
1362                  * We need to set vt_newvt *before* sending the signal or we
1363                  * have a race.
1364                  */
1365                 vc->vt_newvt = new_vc->vc_num;
1366                 if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
1367                         /*
1368                          * It worked. Mark the vt to switch to and
1369                          * return. The process needs to send us a
1370                          * VT_RELDISP ioctl to complete the switch.
1371                          */
1372                         return;
1373                 }
1374
1375                 /*
1376                  * The controlling process has died, so we revert back to
1377                  * normal operation. In this case, we'll also change back
1378                  * to KD_TEXT mode. I'm not sure if this is strictly correct
1379                  * but it saves the agony when the X server dies and the screen
1380                  * remains blanked due to KD_GRAPHICS! It would be nice to do
1381                  * this outside of VT_PROCESS but there is no single process
1382                  * to account for and tracking tty count may be undesirable.
1383                  */
1384                 reset_vc(vc);
1385
1386                 /*
1387                  * Fall through to normal (VT_AUTO) handling of the switch...
1388                  */
1389         }
1390
1391         /*
1392          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
1393          */
1394         if (vc->vc_mode == KD_GRAPHICS)
1395                 return;
1396
1397         complete_change_console(new_vc);
1398 }
1399
1400 /* Perform a kernel triggered VT switch for suspend/resume */
1401
1402 static int disable_vt_switch;
1403
1404 int vt_move_to_console(unsigned int vt, int alloc)
1405 {
1406         int prev;
1407
1408         console_lock();
1409         /* Graphics mode - up to X */
1410         if (disable_vt_switch) {
1411                 console_unlock();
1412                 return 0;
1413         }
1414         prev = fg_console;
1415
1416         if (alloc && vc_allocate(vt)) {
1417                 /* we can't have a free VC for now. Too bad,
1418                  * we don't want to mess the screen for now. */
1419                 console_unlock();
1420                 return -ENOSPC;
1421         }
1422
1423         if (set_console(vt)) {
1424                 /*
1425                  * We're unable to switch to the SUSPEND_CONSOLE.
1426                  * Let the calling function know so it can decide
1427                  * what to do.
1428                  */
1429                 console_unlock();
1430                 return -EIO;
1431         }
1432         console_unlock();
1433         if (vt_waitactive(vt + 1)) {
1434                 pr_debug("Suspend: Can't switch VCs.");
1435                 return -EINTR;
1436         }
1437         return prev;
1438 }
1439
1440 /*
1441  * Normally during a suspend, we allocate a new console and switch to it.
1442  * When we resume, we switch back to the original console.  This switch
1443  * can be slow, so on systems where the framebuffer can handle restoration
1444  * of video registers anyways, there's little point in doing the console
1445  * switch.  This function allows you to disable it by passing it '0'.
1446  */
1447 void pm_set_vt_switch(int do_switch)
1448 {
1449         console_lock();
1450         disable_vt_switch = !do_switch;
1451         console_unlock();
1452 }
1453 EXPORT_SYMBOL(pm_set_vt_switch);