[3.16.y-ckt stable] Patch "drm/vmwgfx: Fix a couple of lock dependency violations" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    drm/vmwgfx: Fix a couple of lock dependency violations

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 7b1f056a84c382a024e46b0504e5d76b90f3240a Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom at vmware.com>
Date: Mon, 9 Mar 2015 01:56:21 -0700
Subject: drm/vmwgfx: Fix a couple of lock dependency violations

commit 5151adb37a5918957f4c33a8d8e7629c0fb00563 upstream.

Experimental lockdep annotation added to the TTM lock has unveiled a
couple of lock dependency violations in the vmwgfx driver. In both
cases it turns out that the device_private::reservation_sem is not
needed so the offending code is moved out of that lock.

Acked-by: Sinclair Yeh <syeh at vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |  8 +++-----
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c     | 14 +++-----------
 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index 87df0b3674fd..6f6fa7d2db47 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2759,13 +2759,11 @@ int vmw_execbuf_ioctl(struct drm_device *dev, void *data,
 				  NULL, arg->command_size, arg->throttle_us,
 				  (void __user *)(unsigned long)arg->fence_rep,
 				  NULL);
-
+	ttm_read_unlock(&dev_priv->reservation_sem);
 	if (unlikely(ret != 0))
-		goto out_unlock;
+		return ret;

 	vmw_kms_cursor_post_execbuf(dev_priv);

-out_unlock:
-	ttm_read_unlock(&dev_priv->reservation_sem);
-	return ret;
+	return 0;
 }
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index bedf18c054d1..d61f6d5ae094 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2037,23 +2037,17 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,
 	int i;
 	struct drm_mode_config *mode_config = &dev->mode_config;

-	ret = ttm_read_lock(&dev_priv->reservation_sem, true);
-	if (unlikely(ret != 0))
-		return ret;
-
 	if (!arg->num_outputs) {
 		struct drm_vmw_rect def_rect = {0, 0, 800, 600};
 		vmw_du_update_layout(dev_priv, 1, &def_rect);
-		goto out_unlock;
+		return 0;
 	}

 	rects_size = arg->num_outputs * sizeof(struct drm_vmw_rect);
 	rects = kcalloc(arg->num_outputs, sizeof(struct drm_vmw_rect),
 			GFP_KERNEL);
-	if (unlikely(!rects)) {
-		ret = -ENOMEM;
-		goto out_unlock;
-	}
+	if (unlikely(!rects))
+		return -ENOMEM;

 	user_rects = (void __user *)(unsigned long)arg->rects;
 	ret = copy_from_user(rects, user_rects, rects_size);
@@ -2078,7 +2072,5 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,

 out_free:
 	kfree(rects);
-out_unlock:
-	ttm_read_unlock(&dev_priv->reservation_sem);
 	return ret;
 }