Daniel Drake wrote:
> Andrew Johnson wrote:
> > When the console is in VT_AUTO/KD_GRAPHICS mode, switching to the
> > SUSPEND_CONSOLE fails, resulting in vt_waitactive() waiting
indefinately
> > or until the task is interrupted. The following patch tests if a
> > console switch can occur in set_console() and returns early if a
console
> > switch is not possible.
> >
> > Signed-off-by: Andrew Johnson <[EMAIL PROTECTED]>
> >
> > diff -rup linux-2.6.20.1/drivers/char/vt.c linux/drivers/char/vt.c
> > --- linux-2.6.20.1/drivers/char/vt.c 2007-02-19
22:34:32.000000000 -
> 0800
> > +++ linux/drivers/char/vt.c 2007-03-08 14:15:41.000000000 -0800
> > @@ -2188,10 +2188,20 @@ static void console_callback(struct work
> > release_console_sem();
> > }
> >
> > -void set_console(int nr)
> > +extern char vt_dont_switch;
> > +
> > +int set_console(int nr)
> > {
> > + struct vc_data *vc = vc_cons[fg_console].d;
> > +
> > + if(!vc_cons_allocated(nr) || vt_dont_switch || vc->vc_mode ==
> > KD_GRAPHICS) {
> > + return -EINVAL;
> > + }
> > +
> > want_console = nr;
> > schedule_console_callback();
> > +
> > + return 0;
> > }
>
> I haven't tested, but I think the above -EINVAL return will break
chvt.
> chvt uses the VT_ACTIVATE ioctl which calls set_console(), and it is
> valid for chvt to be used to change away from a graphics-mode console
--
> that shouldn't be an error condition.
Currently the VT_ACTIVATE ioctl will eventually result in a call to
change_console() which will ignore the change if the console is in
KD_GRAPHICS+VT_AUTO mode. Thus, chvt should fail. However, the return
code from set_console() is ignored in vt_ioctl so no error code will
result (which is the same as current behavior).
-- Andrew
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