vt/console: try harder to print output when panicing

Jesse's initial patch commit said:

"At panic time (i.e.  when oops_in_progress is set) we should try a bit
harder to update the screen and make sure output gets to the VT, since
some drivers are capable of flipping back to it.

So make sure we try to unblank and update the display if called from a
panic context."

I've enhanced this to add a flag to the vc that console layer can set to
indicate they want this behaviour to occur.  This also adds support to
fbcon for that flag and adds an fb flag for drivers to indicate they want
to use the support.  It enables this for KMS drivers.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: James Simmons <jsimmons@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 15 insertions, 9 deletions

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 34bfb056d7a6..82f64ac21191 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -705,7 +705,10 @@ void redraw_screen(struct vc_data *vc, int is_switch)
 			update_attr(vc);
 			clear_buffer_attributes(vc);
 		}
-		if (update && vc->vc_mode != KD_GRAPHICS)
+
+		/* Forcibly update if we're panicing */
+		if ((update && vc->vc_mode != KD_GRAPHICS) ||
+		    vt_force_oops_output(vc))
 			do_update_region(vc, vc->vc_origin, vc->vc_screenbuf_size / 2);
 	}
 	set_cursor(vc);
@@ -743,6 +746,7 @@ static void visual_init(struct vc_data *vc, int num, int init)
 	vc->vc_hi_font_mask = 0;
 	vc->vc_complement_mask = 0;
 	vc->vc_can_do_color = 0;
+	vc->vc_panic_force_write = false;
 	vc->vc_sw->con_init(vc, init);
 	if (!vc->vc_complement_mask)
 		vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
@@ -2506,7 +2510,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
 		goto quit;
 	}
 
-	if (vc->vc_mode != KD_TEXT)
+	if (vc->vc_mode != KD_TEXT && !vt_force_oops_output(vc))
 		goto quit;
 
 	/* undraw cursor first */
@@ -3784,7 +3788,8 @@ void do_unblank_screen(int leaving_gfx)
 		return;
 	}
 	vc = vc_cons[fg_console].d;
-	if (vc->vc_mode != KD_TEXT)
+	/* Try to unblank in oops case too */
+	if (vc->vc_mode != KD_TEXT && !vt_force_oops_output(vc))
 		return; /* but leave console_blanked != 0 */
 
 	if (blankinterval) {
@@ -3793,7 +3798,7 @@ void do_unblank_screen(int leaving_gfx)
 	}
 
 	console_blanked = 0;
-	if (vc->vc_sw->con_blank(vc, 0, leaving_gfx))
+	if (vc->vc_sw->con_blank(vc, 0, leaving_gfx) || vt_force_oops_output(vc))
 		/* Low-level driver cannot restore -> do it ourselves */
 		update_screen(vc);
 	if (console_blank_hook)
diff --git a/drivers/gpu/drm/i915/intel_fb.c b/drivers/gpu/drm/i915/intel_fb.c
index 54acd8b534df..a79525f434a8 100644
--- a/drivers/gpu/drm/i915/intel_fb.c
+++ b/drivers/gpu/drm/i915/intel_fb.c
@@ -130,7 +130,7 @@ static int intelfb_create(struct intel_fbdev *ifbdev,
 
 	strcpy(info->fix.id, "inteldrmfb");
 
-	info->flags = FBINFO_DEFAULT;
+	info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
 	info->fbops = &intelfb_ops;
 
 	/* setup aperture base/size for vesafb takeover */
@@ -148,8 +148,6 @@ static int intelfb_create(struct intel_fbdev *ifbdev,
 	info->fix.smem_start = dev->mode_config.fb_base + obj_priv->gtt_offset;
 	info->fix.smem_len = size;
 
-	info->flags = FBINFO_DEFAULT;
-
 	info->screen_base = ioremap_wc(dev->agp->base + obj_priv->gtt_offset,
 				       size);
 	if (!info->screen_base) {
diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 2fb2444d2322..099f637264aa 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -250,6 +250,7 @@ nouveau_fbcon_create(struct nouveau_fbdev *nfbdev,
 		info->flags = FBINFO_DEFAULT | FBINFO_HWACCEL_COPYAREA |
 			      FBINFO_HWACCEL_FILLRECT |
 			      FBINFO_HWACCEL_IMAGEBLIT;
+	info->flags |= FBINFO_CAN_FORCE_OUTPUT;
 	info->fbops = &nouveau_fbcon_ops;
 	info->fix.smem_start = dev->mode_config.fb_base + nvbo->bo.offset -
 			       dev_priv->vm_vram_base;
diff --git a/drivers/gpu/drm/radeon/radeon_fb.c b/drivers/gpu/drm/radeon/radeon_fb.c
index dc1634bb0c11..dbf86962bdd1 100644
--- a/drivers/gpu/drm/radeon/radeon_fb.c
+++ b/drivers/gpu/drm/radeon/radeon_fb.c
@@ -224,7 +224,7 @@ static int radeonfb_create(struct radeon_fbdev *rfbdev,
 
 	drm_fb_helper_fill_fix(info, fb->pitch, fb->depth);
 
-	info->flags = FBINFO_DEFAULT;
+	info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
 	info->fbops = &radeonfb_ops;
 
 	tmp = radeon_bo_gpu_offset(rbo) - rdev->mc.vram_start;
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 3b3f5749af92..26bf7cbfecc2 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -283,7 +283,8 @@ static inline int fbcon_is_inactive(struct vc_data *vc, struct fb_info *info)
 	struct fbcon_ops *ops = info->fbcon_par;
 
 	return (info->state != FBINFO_STATE_RUNNING ||
-		vc->vc_mode != KD_TEXT || ops->graphics);
+		vc->vc_mode != KD_TEXT || ops->graphics) &&
+		!vt_force_oops_output(vc);
 }
 
 static inline int get_color(struct vc_data *vc, struct fb_info *info,
@@ -1073,6 +1074,7 @@ static void fbcon_init(struct vc_data *vc, int init)
 	if (p->userfont)
 		charcnt = FNTCHARCNT(p->fontdata);
 
+	vc->vc_panic_force_write = !!(info->flags & FBINFO_CAN_FORCE_OUTPUT);
 	vc->vc_can_do_color = (fb_get_color_depth(&info->var, &info->fix)!=1);
 	vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
 	if (charcnt == 256) {