Re: [PATCH] Software Suspend: Fix suspend when console is inVT_AUTO/KD_GRAPHICS mode
From: Andrew Johnson
Date: Fri Mar 09 2007 - 19:06:48 EST
On Fri, 2007-09-03 at 13:19 -0800, Pavel Machek wrote:
> Hi!
>
> >
> > -void set_console(int nr)
> > +extern char vt_dont_switch;
> > +
>
> What does this variable do and why do we want to use it here?
>
It's needed in set_console(). Console switch will fail if this is true.
> 'if ('
>
> > + (vc->vt_mode.mode != VT_PROCESS && vc->vc_mode ==
> KD_GRAPHICS)) {
> > +
> > + return -EINVAL;
> > + }
> > +
>
> I assume you want ...mode == VT_AUTO here?
>
> And big comment explaining why we want this behaviour?
>
> And another big comment explaining why this will not break existing
> set_console() users?
>
See updated comment in attached patch.
> > - set_console(SUSPEND_CONSOLE);
> > + if (set_console(SUSPEND_CONSOLE)) {
> > + /* Unable to change to the new console */
>
> That's not what the comment should say.
>
> It should explain why it is okay to proceed when we can't change to
> text console.
>
See updated comment in attached patch. It's really up to the caller to
decide what to do if we can't switch the console - currently all callers
ignore the return code so I assume that it's okay to proceed anyway.
-- 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 15:48:29.000000000 -0800
@@ -2188,10 +2188,30 @@ 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_AUTO && vc->vc_mode == KD_GRAPHICS)) {
+
+ /*
+ * Console switch will fail in console_callback() or
+ * change_console() so there is no point scheduling
+ * the callback
+ *
+ * Existing set_console() users don't check the return
+ * value so this shouldn't break anything
+ */
+ 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 2007-03-09 15:52:32.000000000 -0800
@@ -27,7 +27,15 @@ int pm_prepare_console(void)
return 1;
}
- set_console(SUSPEND_CONSOLE);
+ if (set_console(SUSPEND_CONSOLE)) {
+ /*
+ * We're unable to switch to the SUSPEND_CONSOLE.
+ * Let the calling function know so it can decide
+ * what to do.
+ */
+ release_console_sem();
+ return 1;
+ }
release_console_sem();
if (vt_waitactive(SUSPEND_CONSOLE)) {
-
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