Re: [PATCH] Software Suspend: Fix suspend when console is inVT_AUTO/KD_GRAPHICS mode

From: Andrew Johnson
Date: Fri Mar 09 2007 - 14:03:33 EST


On Fri, 2007-09-03 at 15:34 +0000, Matthew Garrett wrote:
> On Fri, Mar 09, 2007 at 10:08:05AM +0100, Pavel Machek wrote:
>
> > So... if current console is graphical, we leave X accessing the
> > console... That's bad, because video state is not going to be
> > restored...?
>
> A graphical console is not necessarily X. Is there any requirement for
> there to be a single VT that isn't in text mode? The vt switching is
> a hack, we shouldn't make life difficult for people who have their own
> userspace code that's entirely capable of restoring video state on its
> own.

I realised that the previous patch would disallow a console switch while
running X. Attached is an updated patch with this scenario fixed.

Another approach might be to fail in vt_waitactive() if a console switch
is not going to occur.

-- Andrew

Signed-off-by: Andrew Johnson <ajohnson@xxxxxxxxxxxxx>
---
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 2007-03-09 10:53:32.000000000 -0800
@@ -2188,10 +2188,22 @@ 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->vt_mode.mode != VT_PROCESS && vc->vc_mode == KD_GRAPHICS)) {
+
+ return -EINVAL;
+ }
+
want_console = nr;
schedule_console_callback();
+
+ return 0;
}

struct tty_driver *console_driver;
diff -rup linux-2.6.20.1/drivers/char/vt_ioctl.c
linux/drivers/char/vt_ioctl.c
--- linux-2.6.20.1/drivers/char/vt_ioctl.c 2007-02-19 22:34:32.000000000
-0800
+++ linux/drivers/char/vt_ioctl.c 2007-03-08 14:15:41.000000000 -0800
@@ -34,7 +34,7 @@
#include <linux/kbd_diacr.h>
#include <linux/selection.h>

-static char vt_dont_switch;
+char vt_dont_switch;
extern struct tty_driver *console_driver;

#define VT_IS_IN_USE(i) (console_driver->ttys[i] &&
console_driver->ttys[i]->count)
diff -rup linux-2.6.20.1/include/linux/kbd_kern.h
linux/include/linux/kbd_kern.h
--- linux-2.6.20.1/include/linux/kbd_kern.h 2007-02-19
22:34:32.000000000 -0800
+++ linux/include/linux/kbd_kern.h 2007-03-08 14:15:41.000000000 -0800
@@ -75,7 +75,7 @@ extern int do_poke_blanked_console;

extern void (*kbd_ledfunc)(unsigned int led);

-extern void set_console(int nr);
+extern int set_console(int nr);
extern void schedule_console_callback(void);

static inline void set_leds(void)
diff -rup linux-2.6.20.1/kernel/power/console.c
linux/kernel/power/console.c
--- linux-2.6.20.1/kernel/power/console.c 2007-02-19 22:34:32.000000000
-0800
+++ linux/kernel/power/console.c 2007-03-08 14:15:41.000000000 -0800
@@ -27,7 +27,11 @@ int pm_prepare_console(void)
return 1;
}

- set_console(SUSPEND_CONSOLE);
+ if (set_console(SUSPEND_CONSOLE)) {
+ /* Unable to change to the new console */
+ release_console_sem();
+ return 1;
+ }
release_console_sem();

if (vt_waitactive(SUSPEND_CONSOLE)) {


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