[bug report] drm/xe/display: Implement display support

[Dan Carpenter]

Hello Maarten Lankhorst,

The patch 44e694958b95: "drm/xe/display: Implement display support"
from Aug 17, 2023 (linux-next), leads to the following Smatch static
checker warning:

	drivers/gpu/drm/xe/xe_bo.c:1414 __xe_bo_create_locked()
	error: we previously assumed 'tile' could be null (see line 1408)

drivers/gpu/drm/xe/xe_bo.c
    1404                 xe_vm_get(vm);
    1405         bo->vm = vm;
    1406 
    1407         if (bo->flags & XE_BO_CREATE_GGTT_BIT) {
    1408                 if (!tile && flags & XE_BO_CREATE_STOLEN_BIT)
    1409                         tile = xe_device_get_root_tile(xe);

Let's assume tile is NULL and XE_BO_CREATE_STOLEN_BIT is not set.

    1410 
    1411                 xe_assert(xe, tile);
    1412 
    1413                 if (flags & XE_BO_FIXED_PLACEMENT_BIT) {
--> 1414                         err = xe_ggtt_insert_bo_at(tile->mem.ggtt, bo,
                                                            ^^^^^^^^^^^^^^

    1415                                                    start + bo->size, U64_MAX);
    1416                 } else {
    1417                         err = xe_ggtt_insert_bo(tile->mem.ggtt, bo);
                                                         ^^^^^^^^^^^^^^
Then we will crash.

    1418                 }
    1419                 if (err)
    1420                         goto err_unlock_put_bo;
    1421         }
    1422 
    1423         return bo;
    1424 

regards,
dan carpenter