1 /*
2 * Copyright (C) 2014 Red Hat
3 * Author: Rob Clark <robdclark@gmail.com>
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included in
13 * all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
19 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
20 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
21 * OTHER DEALINGS IN THE SOFTWARE.
22 */
23
24 #ifndef DRM_MODESET_LOCK_H_
25 #define DRM_MODESET_LOCK_H_
26
27 #include <linux/ww_mutex.h>
28
29 struct drm_modeset_lock;
30
31 /**
32 * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
33 * @ww_ctx: base acquire ctx
34 * @contended: used internally for -EDEADLK handling
35 * @locked: list of held locks
36 * @trylock_only: trylock mode used in atomic contexts/panic notifiers
37 * @interruptible: whether interruptible locking should be used.
38 *
39 * Each thread competing for a set of locks must use one acquire
40 * ctx. And if any lock fxn returns -EDEADLK, it must backoff and
41 * retry.
42 */
43 struct drm_modeset_acquire_ctx {
44
45 struct ww_acquire_ctx ww_ctx;
46
47 /*
48 * Contended lock: if a lock is contended you should only call
49 * drm_modeset_backoff() which drops locks and slow-locks the
50 * contended lock.
51 */
52 struct drm_modeset_lock *contended;
53
54 /*
55 * list of held locks (drm_modeset_lock_info)
56 */
57 struct list_head locked;
58
59 /*
60 * Trylock mode, use only for panic handlers!
61 */
62 bool trylock_only;
63
64 /* Perform interruptible waits on this context. */
65 bool interruptible;
66 };
67
68 /*
69 * Keep track of extra locks.
70 */
71 struct drm_modeset_lock_info {
72 struct list_head ctx_entry;
73 struct list_head lock_entry;
74 struct drm_modeset_lock *lock;
75 struct drm_modeset_acquire_ctx *ctx;
76 };
77
78 /**
79 * struct drm_modeset_lock - used for locking modeset resources.
80 * @mutex: resource locking
81 * @head: used to hold it's place on &drm_atomi_state.locked list when
82 * part of an atomic update
83 *
84 * Used for locking CRTCs and other modeset resources.
85 */
86 struct drm_modeset_lock {
87 /*
88 * modeset lock
89 */
90 struct ww_mutex mutex;
91
92 /*
93 * Resources that are locked as part of an atomic update are added
94 * to a list (so we know what to unlock at the end).
95 */
96 struct list_head head;
97 };
98
99 #define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)
100
101 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
102 uint32_t flags);
103 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
104 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
105 int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
106
107 void drm_modeset_lock_init(struct drm_modeset_lock *lock);
108
109 /**
110 * drm_modeset_lock_fini - cleanup lock
111 * @lock: lock to cleanup
112 */
drm_modeset_lock_fini(struct drm_modeset_lock * lock)113 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
114 {
115 WARN_ON(!list_empty(&lock->head));
116 }
117
118 /**
119 * drm_modeset_is_locked - equivalent to mutex_is_locked()
120 * @lock: lock to check
121 */
drm_modeset_is_locked(struct drm_modeset_lock * lock)122 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
123 {
124 return ww_mutex_is_locked(&lock->mutex);
125 }
126
127 int drm_modeset_lock(struct drm_modeset_lock *lock,
128 struct drm_modeset_acquire_ctx *ctx);
129 int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);
130 void drm_modeset_unlock(struct drm_modeset_lock *lock);
131
132 struct drm_device;
133 struct drm_crtc;
134 struct drm_plane;
135
136 void drm_modeset_lock_all(struct drm_device *dev);
137 void drm_modeset_unlock_all(struct drm_device *dev);
138 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
139
140 int drm_modeset_lock_all_ctx(struct drm_device *dev,
141 struct drm_modeset_acquire_ctx *ctx);
142
143 #endif /* DRM_MODESET_LOCK_H_ */
144