drm/xe: Fix a NULL vs IS_ERR() in xe_vm_add_compute_exec_queue()

[ Upstream commit cbc7f3b ]

The xe_preempt_fence_create() function returns error pointers.  It
never returns NULL.  Update the error checking to match.

Fixes: dd08ebf ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Matthew Brost <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rodrigo Vivi <[email protected]>
(cherry picked from commit 75cc23f)
Signed-off-by: Rodrigo Vivi <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: Dan Carpenter

drivers/gpu/drm/xe/xe_vm.c

@@ -240,8 +240,8 @@ int xe_vm_add_compute_exec_queue(struct xe_vm *vm, struct xe_exec_queue *q)
 
 	pfence = xe_preempt_fence_create(q, q->lr.context,
 					 ++q->lr.seqno);
-	if (!pfence) {
-		err = -ENOMEM;
+	if (IS_ERR(pfence)) {
+		err = PTR_ERR(pfence);
 		goto out_fini;
 	}