[PATCH][Option 2] drm/vmwgfx: Fix an fb unlocking bug

[PATCH][Option 2] drm/vmwgfx: Fix an fb unlocking bug

[Thomas Hellstrom]

A regression introduced when the master ttm lock was split into two.

Reported-and-tested-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Cc: <stable@vger.kernel.org> # 3.15.x - 4.2.x
---
The stable commit "drm/ttm: Fixed a read/write lock imbalance" exposes
this bug on kernels 3.15 through 4.2, causing a hang on vmwgfx module
load. Please apply this commit if and only if
"drm/ttm: Fixed a read/write lock imbalance" has been applied.

Upstream commit id:
12617971c443c50750a12a77ea0e08319d161975
---
 drivers/gpu/drm/vmwgfx/vmwgfx_fb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
index 0a474f391fad0157d8a51e5aa2e50d6c4aec69ec..e2d40ebd545583af20c816e88dc4cd47ef306f3d 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
@@ -402,12 +402,12 @@ static int vmw_fb_create_bo(struct vmw_private *vmw_priv,
 
 	*out = vmw_bo;
 
-	ttm_write_unlock(&vmw_priv->fbdev_master.lock);
+	ttm_write_unlock(&vmw_priv->reservation_sem);
 
 	return 0;
 
 err_unlock:
-	ttm_write_unlock(&vmw_priv->fbdev_master.lock);
+	ttm_write_unlock(&vmw_priv->reservation_sem);
 	return ret;
 }
 
-- 
2.5.0

Re: [PATCH][Option 2] drm/vmwgfx: Fix an fb unlocking bug

[Greg KH]

On Thu, Feb 25, 2016 at 10:27:02AM +0100, Thomas Hellstrom wrote:
> A regression introduced when the master ttm lock was split into two.
> 
> Reported-and-tested-by: Brian Paul <brianp@vmware.com>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Brian Paul <brianp@vmware.com>
> Cc: <stable@vger.kernel.org> # 3.15.x - 4.2.x
> ---
> The stable commit "drm/ttm: Fixed a read/write lock imbalance" exposes
> this bug on kernels 3.15 through 4.2, causing a hang on vmwgfx module
> load. Please apply this commit if and only if
> "drm/ttm: Fixed a read/write lock imbalance" has been applied.

What commit id was this one you are referring to?

thanks,

greg k-h

Re: [PATCH][Option 2] drm/vmwgfx: Fix an fb unlocking bug

[Kamal Mostafa]

On Thu, 2016-02-25 at 19:23 +0000, Greg KH wrote:
> On Thu, Feb 25, 2016 at 10:27:02AM +0100, Thomas Hellstrom wrote:
> > A regression introduced when the master ttm lock was split into
> > two.
> > 
> > Reported-and-tested-by: Brian Paul <brianp@vmware.com>
> > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> > Reviewed-by: Brian Paul <brianp@vmware.com>
> > Cc: <stable@vger.kernel.org> # 3.15.x - 4.2.x
> > ---
> > The stable commit "drm/ttm: Fixed a read/write lock imbalance"
> > exposes
> > this bug on kernels 3.15 through 4.2, causing a hang on vmwgfx
> > module
> > load. Please apply this commit if and only if
> > "drm/ttm: Fixed a read/write lock imbalance" has been applied.
> 
> What commit id was this one you are referring to?

025af18 drm/ttm: Fixed a read/write lock imbalance


So... Please apply this commit (i.e. please cherry-pick:

12617971 "drm/vmwgfx: Fix an fb unlocking bug"

) if and only if your stable tree 3.15 through 4.2 carries:

commit 025af189fb44250206dd8a32fa4a682392af3301
Author: Thomas Hellstrom <thellstrom@vmware.com>
Date:   Fri Nov 20 11:43:50 2015 -0800

    drm/ttm: Fixed a read/write lock imbalance