drm/xe/vm: drop vm->destroy_work

Now that we no longer grab the usm.lock mutex (which might sleep) it
looks like it should be safe to directly perform xe_vm_free when vm
refcount reaches zero, instead of punting that off to some worker.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412113144.259426-5-matthew.auld@intel.com

drivers/gpu/drm/xe/xe_vm.c

@@ -1179,8 +1179,6 @@ static const struct xe_pt_ops xelp_pt_ops = {
 	.pde_encode_bo = xelp_pde_encode_bo,
 };
 
-static void vm_destroy_work_func(struct work_struct *w);
-
 /**
  * xe_vm_create_scratch() - Setup a scratch memory pagetable tree for the
  * given tile and vm.
@@ -1260,8 +1258,6 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags)
 	init_rwsem(&vm->userptr.notifier_lock);
 	spin_lock_init(&vm->userptr.invalidated_lock);
 
-	INIT_WORK(&vm->destroy_work, vm_destroy_work_func);
-
 	INIT_LIST_HEAD(&vm->preempt.exec_queues);
 	vm->preempt.min_run_period_ms = 10;	/* FIXME: Wire up to uAPI */
 
@@ -1499,10 +1495,9 @@ void xe_vm_close_and_put(struct xe_vm *vm)
 	xe_vm_put(vm);
 }
 
-static void vm_destroy_work_func(struct work_struct *w)
+static void xe_vm_free(struct drm_gpuvm *gpuvm)
 {
-	struct xe_vm *vm =
-		container_of(w, struct xe_vm, destroy_work);
+	struct xe_vm *vm = container_of(gpuvm, struct xe_vm, gpuvm);
 	struct xe_device *xe = vm->xe;
 	struct xe_tile *tile;
 	u8 id;
@@ -1522,14 +1517,6 @@ static void vm_destroy_work_func(struct work_struct *w)
 	kfree(vm);
 }
 
-static void xe_vm_free(struct drm_gpuvm *gpuvm)
-{
-	struct xe_vm *vm = container_of(gpuvm, struct xe_vm, gpuvm);
-
-	/* To destroy the VM we need to be able to sleep */
-	queue_work(system_unbound_wq, &vm->destroy_work);
-}
-
 struct xe_vm *xe_vm_lookup(struct xe_file *xef, u32 id)
 {
 	struct xe_vm *vm;

drivers/gpu/drm/xe/xe_vm_types.h

@@ -177,13 +177,6 @@ struct xe_vm {
 	 */
 	struct list_head rebind_list;
 
-	/**
-	 * @destroy_work: worker to destroy VM, needed as a dma_fence signaling
-	 * from an irq context can be last put and the destroy needs to be able
-	 * to sleep.
-	 */
-	struct work_struct destroy_work;
-
 	/**
 	 * @rftree: range fence tree to track updates to page table structure.
 	 * Used to implement conflict tracking between independent bind engines.