fbcon: Do not takeover the console from atomic context

Taking over the console involves allocating mem with GFP_KERNEL, talking
to drm drivers, etc. So this should not be done from an atomic context.

But the console-output trigger deferred console takeover may happen from an
atomic context, which leads to "BUG: sleeping function called from invalid
context" errors.

This commit fixes these errors by doing the deferred takeover from a
workqueue.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
[b.zolnierkie: remove unused variable]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index ef8b2d0b7071b3f67e3a224eb066dc3a5be7352c..75ebbbf0a1fbb5b4e3d633ced517967d94d02e6b 100644 (file)
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -3592,13 +3592,24 @@ static int fbcon_init_device(void)
 }
 
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+static void fbcon_register_existing_fbs(struct work_struct *work)
+{
+       int i;
+
+       console_lock();
+
+       for_each_registered_fb(i)
+               fbcon_fb_registered(registered_fb[i]);
+
+       console_unlock();
+}
+
 static struct notifier_block fbcon_output_nb;
+static DECLARE_WORK(fbcon_deferred_takeover_work, fbcon_register_existing_fbs);
 
 static int fbcon_output_notifier(struct notifier_block *nb,
                                 unsigned long action, void *data)
 {
-       int i;
-
        WARN_CONSOLE_UNLOCKED();
 
        pr_info("fbcon: Taking over console\n");
@@ -3607,8 +3618,8 @@ static int fbcon_output_notifier(struct notifier_block *nb,
        deferred_takeover = false;
        logo_shown = FBCON_LOGO_DONTSHOW;
 
-       for_each_registered_fb(i)
-               fbcon_fb_registered(registered_fb[i]);
+       /* We may get called in atomic context */
+       schedule_work(&fbcon_deferred_takeover_work);
 
        return NOTIFY_OK;
 }