drm/vmwgfx: Fix false lockdep warning

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=ac49251b6bf428b8f4fb1ed8859219f0a72b5db4
Commit:     ac49251b6bf428b8f4fb1ed8859219f0a72b5db4
Parent:     8d17fb4455eadbf2642e34e5584d0b0de64d33a8
Author:     Thomas Hellstrom <thellstrom at vmware.com>
AuthorDate: Fri Nov 15 00:06:47 2013 -0800
Committer:  Thomas Hellstrom <thellstrom at vmware.com>
CommitDate: Mon Nov 18 00:40:05 2013 -0800

    drm/vmwgfx: Fix false lockdep warning
    
    A lockdep warning is hit when evicting surfaces and reserving the backup
    buffer. Since this buffer can only be reserved by the process holding the
    surface reservation or by the buffer eviction processes that use tryreserve,
    there is no real deadlock here, but there's no other way to silence lockdep
    than to use a tryreserve. This means the reservation might fail if the buffer
    is about to be evicted or swapped out, but we now have code in place to
    handle that reasonably well.
    
    Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
    Reviewed-by: Jakob Bornecrantz <jakob at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index 252501a..5aace80 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -994,7 +994,6 @@ void vmw_resource_unreserve(struct vmw_resource *res,
  */
 static int
 vmw_resource_check_buffer(struct vmw_resource *res,
-			  struct ww_acquire_ctx *ticket,
 			  bool interruptible,
 			  struct ttm_validate_buffer *val_buf)
 {
@@ -1011,7 +1010,7 @@ vmw_resource_check_buffer(struct vmw_resource *res,
 	INIT_LIST_HEAD(&val_list);
 	val_buf->bo = ttm_bo_reference(&res->backup->base);
 	list_add_tail(&val_buf->head, &val_list);
-	ret = ttm_eu_reserve_buffers(ticket, &val_list);
+	ret = ttm_eu_reserve_buffers(NULL, &val_list);
 	if (unlikely(ret != 0))
 		goto out_no_reserve;
 
@@ -1029,7 +1028,7 @@ vmw_resource_check_buffer(struct vmw_resource *res,
 	return 0;
 
 out_no_validate:
-	ttm_eu_backoff_reservation(ticket, &val_list);
+	ttm_eu_backoff_reservation(NULL, &val_list);
 out_no_reserve:
 	ttm_bo_unref(&val_buf->bo);
 	if (backup_dirty)
@@ -1074,8 +1073,7 @@ int vmw_resource_reserve(struct vmw_resource *res, bool no_backup)
  * @val_buf:        Backup buffer information.
  */
 static void
-vmw_resource_backoff_reservation(struct ww_acquire_ctx *ticket,
-				 struct ttm_validate_buffer *val_buf)
+vmw_resource_backoff_reservation(struct ttm_validate_buffer *val_buf)
 {
 	struct list_head val_list;
 
@@ -1084,7 +1082,7 @@ vmw_resource_backoff_reservation(struct ww_acquire_ctx *ticket,
 
 	INIT_LIST_HEAD(&val_list);
 	list_add_tail(&val_buf->head, &val_list);
-	ttm_eu_backoff_reservation(ticket, &val_list);
+	ttm_eu_backoff_reservation(NULL, &val_list);
 	ttm_bo_unref(&val_buf->bo);
 }
 
@@ -1099,14 +1097,12 @@ int vmw_resource_do_evict(struct vmw_resource *res, bool interruptible)
 {
 	struct ttm_validate_buffer val_buf;
 	const struct vmw_res_func *func = res->func;
-	struct ww_acquire_ctx ticket;
 	int ret;
 
 	BUG_ON(!func->may_evict);
 
 	val_buf.bo = NULL;
-	ret = vmw_resource_check_buffer(res, &ticket, interruptible,
-					&val_buf);
+	ret = vmw_resource_check_buffer(res, interruptible, &val_buf);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -1121,7 +1117,7 @@ int vmw_resource_do_evict(struct vmw_resource *res, bool interruptible)
 	res->backup_dirty = true;
 	res->res_dirty = false;
 out_no_unbind:
-	vmw_resource_backoff_reservation(&ticket, &val_buf);
+	vmw_resource_backoff_reservation(&val_buf);
 
 	return ret;
 }