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vt: add an activate and lock

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X and other graphical interfaces need to be able to flip to a console
and lock it into graphics mode without races.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox
2009-09-19 13:13:26 -07:00
committed by Live-CD User
parent a5eb56242d
commit d3b5cffcf8
2 changed files with 44 additions and 1 deletions
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38
drivers/char/vt_ioctl.c
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@@ -972,6 +972,41 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
}
break;
case VT_SETACTIVATE:
{
struct vt_setactivate vsa;
if (!perm)
goto eperm;
if (copy_from_user(&vsa, (struct vt_setactivate __user *)arg,
sizeof(struct vt_setactivate)))
return -EFAULT;
if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
ret = -ENXIO;
else {
vsa.console--;
acquire_console_sem();
ret = vc_allocate(vsa.console);
if (ret == 0) {
struct vc_data *nvc;
/* This is safe providing we don't drop the
console sem between vc_allocate and
finishing referencing nvc */
nvc = vc_cons[vsa.console].d;
nvc->vt_mode = vsa.mode;
nvc->vt_mode.frsig = 0;
put_pid(nvc->vt_pid);
nvc->vt_pid = get_pid(task_pid(current));
}
release_console_sem();
if (ret)
break;
/* Commence switch and lock */
set_console(arg);
}
}
/*
* wait until the specified VT has been activated
*/
@@ -1342,7 +1377,8 @@ void vc_SAK(struct work_struct *work)
}
/*
* Performs the back end of a vt switch
* Performs the back end of a vt switch. Called under the console
* semaphore.
*/
static void complete_change_console(struct vc_data *vc)
{