drm/vmwgfx: Fix a destoy-while-held mutex problem.

When validating legacy surfaces, the backup bo might be destroyed at
surface validate time. However, the kms resource validation code may have
the bo reserved, so we will destroy a locked mutex. While there shouldn't
be any other users of that mutex when it is destroyed, it causes a lock
leak and thus throws a lockdep error.

Fix this by having the kms resource validation code hold a reference to
the bo while we have it reserved. We do this by introducing a validation
context which might come in handy when the kms code is extended to validate
multiple resources or buffers.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
index b68d74888ab1..6b969e5dea2a 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
@@ -980,12 +980,13 @@ int vmw_kms_stdu_surface_dirty(struct vmw_private *dev_priv,
 	struct vmw_framebuffer_surface *vfbs =
 		container_of(framebuffer, typeof(*vfbs), base);
 	struct vmw_stdu_dirty sdirty;
+	struct vmw_validation_ctx ctx;
 	int ret;
 
 	if (!srf)
 		srf = &vfbs->surface->res;
 
-	ret = vmw_kms_helper_resource_prepare(srf, true);
+	ret = vmw_kms_helper_resource_prepare(srf, true, &ctx);
 	if (ret)
 		return ret;
 
@@ -1008,7 +1009,7 @@ int vmw_kms_stdu_surface_dirty(struct vmw_private *dev_priv,
 				   dest_x, dest_y, num_clips, inc,
 				   &sdirty.base);
 out_finish:
-	vmw_kms_helper_resource_finish(srf, out_fence);
+	vmw_kms_helper_resource_finish(&ctx, out_fence);
 
 	return ret;
 }