[PATCH] swsusp: fix suspend when console is in VT_AUTO+KD_GRAPHICS mode

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.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Andrew Johnson <ajohnson@intrinsyc.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 20 insertions, 2 deletions

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index c3f8e383933b..0fefe2a28055 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -2185,10 +2185,28 @@ static void console_callback(struct work_struct *ignored)
         release_console_sem();
 }
 
-void set_console(int nr)
+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 --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 3a5d301e783b..1fa2da8f4fbe 100644
--- a/drivers/char/vt_ioctl.c
+++ b/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)