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1/* SPDX-License-Identifier: GPL-2.0 OR MIT */
2
3#ifndef __DRM_EXEC_H__
4#define __DRM_EXEC_H__
5
6#include <linux/compiler.h>
7#include <linux/ww_mutex.h>
8
9#define DRM_EXEC_INTERRUPTIBLE_WAIT BIT(0)
10#define DRM_EXEC_IGNORE_DUPLICATES BIT(1)
11
12/*
13 * Dummy value used to initially enter the retry loop.
14 * internal use only.
15 */
16#define DRM_EXEC_DUMMY ((void *)~0)
17
18struct drm_gem_object;
19
20/**
21 * struct drm_exec - Execution context
22 */
23struct drm_exec {
24 /**
25 * @flags: Flags to control locking behavior
26 */
27 u32 flags;
28
29 /**
30 * @ticket: WW ticket used for acquiring locks
31 */
32 struct ww_acquire_ctx ticket;
33
34 /**
35 * @num_objects: number of objects locked
36 */
37 unsigned int num_objects;
38
39 /**
40 * @max_objects: maximum objects in array
41 */
42 unsigned int max_objects;
43
44 /**
45 * @objects: array of the locked objects
46 */
47 struct drm_gem_object **objects;
48
49 /**
50 * @contended: contended GEM object we backed off for
51 */
52 struct drm_gem_object *contended;
53
54 /**
55 * @prelocked: already locked GEM object due to contention
56 */
57 struct drm_gem_object *prelocked;
58};
59
60/**
61 * drm_exec_obj() - Return the object for a give drm_exec index
62 * @exec: Pointer to the drm_exec context
63 * @index: The index.
64 *
65 * Return: Pointer to the locked object corresponding to @index if
66 * index is within the number of locked objects. NULL otherwise.
67 */
68static inline struct drm_gem_object *
69drm_exec_obj(struct drm_exec *exec, unsigned long index)
70{
71 return index < exec->num_objects ? exec->objects[index] : NULL;
72}
73
74/* Helper for drm_exec_for_each_locked_object(). Internal use only. */
75#define __drm_exec_for_each_locked_object(exec, obj, __index) \
76 for (unsigned long __index = 0; ((obj) = drm_exec_obj(exec, __index)); \
77 ++__index)
78/**
79 * drm_exec_for_each_locked_object - iterate over all the locked objects
80 * @exec: drm_exec object
81 * @obj: the current GEM object
82 *
83 * Iterate over all the explicitly locked GEM objects inside the drm_exec
84 * container, except for the contended and implicit prelocked one.
85 */
86#define drm_exec_for_each_locked_object(exec, obj) \
87 __drm_exec_for_each_locked_object(exec, obj, __UNIQUE_ID(drm_exec))
88
89/* Helper for drm_exec_for_each_locked_object_reverse(). Internal use only. */
90#define __drm_exec_for_each_locked_object_reverse(exec, obj, __index) \
91 for (unsigned long __index = (exec)->num_objects - 1; \
92 ((obj) = drm_exec_obj(exec, __index)); --__index)
93/**
94 * drm_exec_for_each_locked_object_reverse - iterate over all the locked
95 * objects in reverse locking order
96 * @exec: drm_exec object
97 * @obj: the current GEM object
98 *
99 * Iterate over all the explicitly locked GEM objects inside the drm_exec
100 * container in reverse locking order. Note that the internal index may wrap
101 * around, but that will be caught by drm_exec_obj(), returning a NULL object.
102 */
103#define drm_exec_for_each_locked_object_reverse(exec, obj) \
104 __drm_exec_for_each_locked_object_reverse(exec, obj, \
105 __UNIQUE_ID(drm_exec))
106
107/**
108 * drm_exec_until_all_locked - loop until all GEM objects are locked
109 * @exec: drm_exec object
110 *
111 * Core functionality of the drm_exec object. Loops until all GEM objects are
112 * locked and no more contention exists. At the beginning of the loop it is
113 * guaranteed that no GEM object is locked.
114 *
115 * A global label name drm_exec_retry is used, if you need to use more than one
116 * instance of this macro in the same function the label needs to be made local
117 * to the block with the __label__ keyword.
118 */
119#define drm_exec_until_all_locked(exec) \
120 for (bool const __maybe_unused __drm_exec_loop = false; \
121 drm_exec_cleanup(exec);) \
122 if (false) { \
123drm_exec_retry: __maybe_unused; \
124 continue; \
125 } else
126
127/**
128 * drm_exec_retry_on_contention - restart the loop to grap all locks
129 * @exec: drm_exec object
130 *
131 * Control flow helper to continue when a contention was detected and we need to
132 * clean up and re-start the loop to prepare all GEM objects.
133 * The __drm_exec_loop check exists to prevent usage outside of an
134 * drm_exec_until_all_locked() loop.
135 */
136#define drm_exec_retry_on_contention(exec) \
137 do { \
138 if (unlikely(drm_exec_is_contended(exec))) \
139 goto drm_exec_retry; \
140 } while (__drm_exec_loop)
141
142/**
143 * drm_exec_is_contended - check for contention
144 * @exec: drm_exec object
145 *
146 * Returns true if the drm_exec object has run into some contention while
147 * locking a GEM object and needs to clean up.
148 */
149static inline bool drm_exec_is_contended(struct drm_exec *exec)
150{
151 return !!exec->contended;
152}
153
154/**
155 * drm_exec_retry() - Unconditionally restart the loop to grab all locks.
156 * @exec: drm_exec object
157 *
158 * Unconditionally retry the loop to lock all objects. For consistency,
159 * the exec object needs to be newly initialized.
160 * The __drm_exec_loop check exists to prevent usage outside of an
161 * drm_exec_until_all_locked() loop.
162 */
163#define drm_exec_retry(_exec) \
164 do { \
165 WARN_ON((_exec)->contended != DRM_EXEC_DUMMY); \
166 goto drm_exec_retry; \
167 } while (__drm_exec_loop)
168
169/**
170 * drm_exec_ticket - return the ww_acquire_ctx for this exec context
171 * @exec: drm_exec object
172 *
173 * Return: Pointer to the ww_acquire_ctx embedded in @exec.
174 */
175static inline struct ww_acquire_ctx *drm_exec_ticket(struct drm_exec *exec)
176{
177 return &exec->ticket;
178}
179
180void drm_exec_init(struct drm_exec *exec, u32 flags, unsigned nr);
181void drm_exec_fini(struct drm_exec *exec);
182bool drm_exec_cleanup(struct drm_exec *exec);
183int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
184void drm_exec_unlock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
185int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
186 unsigned int num_fences);
187int drm_exec_prepare_array(struct drm_exec *exec,
188 struct drm_gem_object **objects,
189 unsigned int num_objects,
190 unsigned int num_fences);
191
192#endif