[PATCH] drm/radeon: deal with errors from framebuffer init path.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

We've been seeing a very occasional oops on a 32-bit rn50 platform running EL6
kernels at boot. It seems to be due to one of these functions failing and
us then accessing a NULL-300 pointer.

This should prevent the oops and give some info in the logs as to what is going on.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 drivers/gpu/drm/radeon/radeon_display.c |   18 +++++++++++++++---
 drivers/gpu/drm/radeon/radeon_fb.c      |   11 ++++++++++-
 drivers/gpu/drm/radeon/radeon_mode.h    |    2 +-
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 8c49fef..3d31433 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -1078,15 +1078,21 @@ static const struct drm_framebuffer_funcs radeon_fb_funcs = {
 	.create_handle = radeon_user_framebuffer_create_handle,
 };
 
-void
+int
 radeon_framebuffer_init(struct drm_device *dev,
 			struct radeon_framebuffer *rfb,
 			struct drm_mode_fb_cmd2 *mode_cmd,
 			struct drm_gem_object *obj)
 {
+	int ret;
 	rfb->obj = obj;
-	drm_framebuffer_init(dev, &rfb->base, &radeon_fb_funcs);
+	ret = drm_framebuffer_init(dev, &rfb->base, &radeon_fb_funcs);
+	if (ret) {
+		rfb->obj = NULL;
+		return ret;
+	}
 	drm_helper_mode_fill_fb_struct(&rfb->base, mode_cmd);
+	return 0;
 }
 
 static struct drm_framebuffer *
@@ -1096,6 +1102,7 @@ radeon_user_framebuffer_create(struct drm_device *dev,
 {
 	struct drm_gem_object *obj;
 	struct radeon_framebuffer *radeon_fb;
+	int ret;
 
 	obj = drm_gem_object_lookup(dev, file_priv, mode_cmd->handles[0]);
 	if (obj ==  NULL) {
@@ -1108,7 +1115,12 @@ radeon_user_framebuffer_create(struct drm_device *dev,
 	if (radeon_fb == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	radeon_framebuffer_init(dev, radeon_fb, mode_cmd, obj);
+	ret = radeon_framebuffer_init(dev, radeon_fb, mode_cmd, obj);
+	if (ret) {
+		kfree(radeon_fb);
+		drm_gem_object_unreference_unlocked(obj);
+		return NULL;
+	}
 
 	return &radeon_fb->base;
 }
diff --git a/drivers/gpu/drm/radeon/radeon_fb.c b/drivers/gpu/drm/radeon/radeon_fb.c
index cf2bf35..195471c 100644
--- a/drivers/gpu/drm/radeon/radeon_fb.c
+++ b/drivers/gpu/drm/radeon/radeon_fb.c
@@ -209,6 +209,11 @@ static int radeonfb_create(struct radeon_fbdev *rfbdev,
 							  sizes->surface_depth);
 
 	ret = radeonfb_create_pinned_object(rfbdev, &mode_cmd, &gobj);
+	if (ret) {
+		DRM_ERROR("failed to create fbcon object %d\n", ret);
+		return ret;
+	}
+
 	rbo = gem_to_radeon_bo(gobj);
 
 	/* okay we have an object now allocate the framebuffer */
@@ -220,7 +225,11 @@ static int radeonfb_create(struct radeon_fbdev *rfbdev,
 
 	info->par = rfbdev;
 
-	radeon_framebuffer_init(rdev->ddev, &rfbdev->rfb, &mode_cmd, gobj);
+	ret = radeon_framebuffer_init(rdev->ddev, &rfbdev->rfb, &mode_cmd, gobj);
+	if (ret) {
+		DRM_ERROR("failed to initalise framebuffer %d\n", ret);
+		goto out_unref;
+	}
 
 	fb = &rfbdev->rfb.base;
 
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 4330e32..8a85598 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -649,7 +649,7 @@ extern void radeon_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
 				     u16 blue, int regno);
 extern void radeon_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 				     u16 *blue, int regno);
-void radeon_framebuffer_init(struct drm_device *dev,
+int radeon_framebuffer_init(struct drm_device *dev,
 			     struct radeon_framebuffer *rfb,
 			     struct drm_mode_fb_cmd2 *mode_cmd,
 			     struct drm_gem_object *obj);
-- 
1.7.7.6