Add patch fixing FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER breaking

VT switching when combined with vgacon (rhbz#1610562)

0009-fbcon-Only-defer-console-takeover-if-the-current-con.patch

@@ -0,0 +1,100 @@
+From 317b698406457eb97277d4220126683a59c74fd8 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Wed, 1 Aug 2018 15:19:52 +0200
+Subject: [PATCH] fbcon: Only defer console takeover if the current
+ console driver is the dummycon
+
+We rely on dummycon's output notifier mechanism to defer the takeover.
+
+If say vgacon is the current console driver then dummycon will never get
+used so its output notifier will also never get called and fbcon never
+takes over. This commit fixes this by only deferring the console takeover
+if the current console driver is the dummycon driver.
+
+This commit also moves the entirety of fbcon_start under the console_lock,
+since the conswitchp which fbcon_start now checks is protected by it.
+
+This commit also inlines fbcon_register_output_notifier, since we now
+need a #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER in fbcon_start
+anyways because of the write access to the deferred_takeover variable,
+this has the added advantage that it puts the
+dummycon_register_output_notifier() call directly after the "conswitchp !=
+&dummy_con" comparison making it clear why that check is there.
+
+Note the arch setup code will set conswitchp to either dummy_con or
+vga_con, in the cases where it gets set to vga_con even though their is
+no vga_con present we rely on vga_con_startup() to set conswitchp to
+dummy_con. vga_con_startup() is guaranteed to happen before
+fb_console_init() as it gets called as a console_initcall where as
+fb_console_init() gets called as a subsys_initcall.
+
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+ drivers/video/fbdev/core/fbcon.c | 24 ++++++++++--------------
+ 1 file changed, 10 insertions(+), 14 deletions(-)
+
+diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
+index e30d3a138c97..ef8b2d0b7071 100644
+--- a/drivers/video/fbdev/core/fbcon.c
++++ b/drivers/video/fbdev/core/fbcon.c
+@@ -3612,38 +3612,34 @@ static int fbcon_output_notifier(struct notifier_block *nb,
+ 
+ 	return NOTIFY_OK;
+ }
+-
+-static void fbcon_register_output_notifier(void)
+-{
+-	fbcon_output_nb.notifier_call = fbcon_output_notifier;
+-	dummycon_register_output_notifier(&fbcon_output_nb);
+-}
+-#else
+-static inline void fbcon_register_output_notifier(void) {}
+ #endif
+ 
+ static void fbcon_start(void)
+ {
++	WARN_CONSOLE_UNLOCKED();
++
++#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
++	if (conswitchp != &dummy_con)
++		deferred_takeover = false;
++
+ 	if (deferred_takeover) {
+-		fbcon_register_output_notifier();
++		fbcon_output_nb.notifier_call = fbcon_output_notifier;
++		dummycon_register_output_notifier(&fbcon_output_nb);
+ 		return;
+ 	}
++#endif
+ 
+ 	if (num_registered_fb) {
+ 		int i;
+ 
+-		console_lock();
+-
+ 		for (i = 0; i < FB_MAX; i++) {
+ 			if (registered_fb[i] != NULL) {
+ 				info_idx = i;
+ 				break;
+ 			}
+ 		}
+ 
+ 		do_fbcon_takeover(0);
+-		console_unlock();
+-
+ 	}
+ }
+ 
+@@ -3724,8 +3720,8 @@ void __init fb_console_init(void)
+ 	for (i = 0; i < MAX_NR_CONSOLES; i++)
+ 		con2fb_map[i] = -1;
+ 
+-	console_unlock();
+ 	fbcon_start();
++	console_unlock();
+ }
+ 
+ #ifdef MODULE
+-- 
+2.18.0
+

kernel.spec

@@ -644,6 +644,8 @@ Patch525: 0005-efi-bgrt-Drop-__initdata-from-bgrt_image_size.patch
 Patch526: 0006-efifb-Copy-the-ACPI-BGRT-boot-graphics-to-the-frameb.patch
 Patch527: 0007-efifb-BGRT-Do-not-copy-the-boot-graphics-for-non-nat.patch
 Patch528: 0008-console-dummycon-export-dummycon_-un-register_output.patch
+# Deferred fbcon takeover bugfix, pending upstream
+Patch529: 0009-fbcon-Only-defer-console-takeover-if-the-current-con.patch
 
 # END OF PATCH DEFINITIONS
 
@@ -1904,6 +1906,10 @@ fi
 #
 #
 %changelog
+* Wed Aug 01 2018 Hans de Goede <hdegoede@redhat.com>
+- Add patch fixing FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER breaking
+  VT switching when combined with vgacon (rhbz#1610562)
+
 * Wed Aug 01 2018 Laura Abbott <labbott@redhat.com> - 4.18.0-0.rc7.git1.1
 - Linux v4.18-rc7-90-gc1d61e7fe376