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Software Suspend: Fix suspend when console is in VT_AUTO+KD_GRAPHICS mode

PATCH In review Andrew Johnson 2 participants 2 messages Mar 12, 2007

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#0 lore raw

PATCH 1/1 Software Suspend: Fix suspend when console is in VT_AUTO+KD_GRAPHICS mode

Hi All,

When the console is in VT_AUTO+KD_GRAPHICS mode, switching to the SUSPEND_CONSOLE fails, resulting in vt_waitactive() waiting indefinitely or until the task is interrupted. This patch tests if a console switch can occur in set_console() and returns early if a console switch is not possible.

-- Andrew

---

drivers/char/vt.c +21 -1
diff -rup linux-2.6.20.1/drivers/char/vt.c linux/drivers/char/vt.c
@@ -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;
drivers/char/vt_ioctl.c +1 -1
diff -rup linux-2.6.20.1/drivers/char/vt_ioctl.c linux/drivers/char/vt_ioctl.c
@@ -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)
include/linux/kbd_kern.h +1 -1
diff -rup linux-2.6.20.1/include/linux/kbd_kern.h linux/include/linux/kbd_kern.h
@@ -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)
kernel/power/console.c +9 -1
diff -rup linux-2.6.20.1/kernel/power/console.c linux/kernel/power/console.c
@@ -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)) {
#1 lore raw

Hi!

Quoted 7 lines

When the console is in VT_AUTO+KD_GRAPHICS mode, switching to the SUSPEND_CONSOLE fails, resulting in vt_waitactive() waiting indefinitely or until the task is interrupted. This patch tests if a console switch can occur in set_console() and returns early if a console switch is not possible.

ACK. (I hope it still applies to latest mainline).

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