1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2020 Intel Corporation
4  */
5 #include <linux/dma-resv.h>
6 #include "i915_gem_ww.h"
7 #include "gem/i915_gem_object.h"
8 
i915_gem_ww_ctx_init(struct i915_gem_ww_ctx * ww,bool intr)9 void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ww, bool intr)
10 {
11 	ww_acquire_init(&ww->ctx, &reservation_ww_class);
12 	INIT_LIST_HEAD(&ww->obj_list);
13 	ww->intr = intr;
14 	ww->contended = NULL;
15 }
16 
i915_gem_ww_ctx_unlock_all(struct i915_gem_ww_ctx * ww)17 static void i915_gem_ww_ctx_unlock_all(struct i915_gem_ww_ctx *ww)
18 {
19 	struct drm_i915_gem_object *obj;
20 
21 	while ((obj = list_first_entry_or_null(&ww->obj_list, struct drm_i915_gem_object, obj_link))) {
22 		list_del(&obj->obj_link);
23 		i915_gem_object_unlock(obj);
24 		i915_gem_object_put(obj);
25 	}
26 }
27 
i915_gem_ww_unlock_single(struct drm_i915_gem_object * obj)28 void i915_gem_ww_unlock_single(struct drm_i915_gem_object *obj)
29 {
30 	list_del(&obj->obj_link);
31 	i915_gem_object_unlock(obj);
32 	i915_gem_object_put(obj);
33 }
34 
i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx * ww)35 void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ww)
36 {
37 	i915_gem_ww_ctx_unlock_all(ww);
38 	WARN_ON(ww->contended);
39 	ww_acquire_fini(&ww->ctx);
40 }
41 
i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx * ww)42 int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ww)
43 {
44 	int ret = 0;
45 
46 	if (WARN_ON(!ww->contended))
47 		return -EINVAL;
48 
49 	i915_gem_ww_ctx_unlock_all(ww);
50 	if (ww->intr)
51 		ret = dma_resv_lock_slow_interruptible(ww->contended->base.resv, &ww->ctx);
52 	else
53 		dma_resv_lock_slow(ww->contended->base.resv, &ww->ctx);
54 
55 	if (!ret)
56 		list_add_tail(&ww->contended->obj_link, &ww->obj_list);
57 	else
58 		i915_gem_object_put(ww->contended);
59 
60 	ww->contended = NULL;
61 
62 	return ret;
63 }
64