Patch "drm/nouveau/fbcon: take runpm reference when userspace has an open fd" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

drm/nouveau/fbcon: take runpm reference when userspace has an open fd

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-nouveau-fbcon-take-runpm-reference-when-userspace-has-an-open-fd.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ben Skeggs <[email protected]>
Date: Fri, 2 Oct 2015 14:03:19 +1000
Subject: drm/nouveau/fbcon: take runpm reference when userspace has an open fd

From: Ben Skeggs <[email protected]>

commit f231976c2e8964ceaa9250e57d27c35ff03825c2 upstream.

We need to do this in order to prevent accesses to the device while it's powered down. Userspace may have an mmap of the fb, and there's no good way (that I know of) to prevent it from touching the device otherwise.

This fixes some nasty races between runpm and plymouth on some systems, which result in the GPU getting very upset and hanging the boot.

---
 drivers/gpu/drm/nouveau/nouveau_fbcon.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

@@ -178,8 +178,30 @@ nouveau_fbcon_sync(struct fb_info *info)
 	return 0;
 }
 
+static int
+nouveau_fbcon_open(struct fb_info *info, int user)
+{
+	struct nouveau_fbdev *fbcon = info->par;
+	struct nouveau_drm *drm = nouveau_drm(fbcon->dev);
+	int ret = pm_runtime_get_sync(drm->dev->dev);
+	if (ret < 0 && ret != -EACCES)
+		return ret;
+	return 0;
+}
+
+static int
+nouveau_fbcon_release(struct fb_info *info, int user)
+{
+	struct nouveau_fbdev *fbcon = info->par;
+	struct nouveau_drm *drm = nouveau_drm(fbcon->dev);
+	pm_runtime_put(drm->dev->dev);
+	return 0;
+}
+
 static struct fb_ops nouveau_fbcon_ops = {
 	.owner = THIS_MODULE,
+	.fb_open = nouveau_fbcon_open,
+	.fb_release = nouveau_fbcon_release,
 	.fb_check_var = drm_fb_helper_check_var,
 	.fb_set_par = drm_fb_helper_set_par,
 	.fb_fillrect = nouveau_fbcon_fillrect,

@@ -195,6 +217,8 @@ static struct fb_ops nouveau_fbcon_ops =
 
 static struct fb_ops nouveau_fbcon_sw_ops = {
 	.owner = THIS_MODULE,
+	.fb_open = nouveau_fbcon_open,
+	.fb_release = nouveau_fbcon_release,
 	.fb_check_var = drm_fb_helper_check_var,
 	.fb_set_par = drm_fb_helper_set_par,
 	.fb_fillrect = cfb_fillrect,

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/drm-nouveau-fbcon-take-runpm-reference-when-userspace-has-an-open-fd.patch