drm_modeset_lock.h revision 1.1.1.2
1 /* $NetBSD: drm_modeset_lock.h,v 1.1.1.2 2021/12/18 20:15:57 riastradh Exp $ */ 2 3 /* 4 * Copyright (C) 2014 Red Hat 5 * Author: Rob Clark <robdclark (at) gmail.com> 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a 8 * copy of this software and associated documentation files (the "Software"), 9 * to deal in the Software without restriction, including without limitation 10 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 11 * and/or sell copies of the Software, and to permit persons to whom the 12 * Software is furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 21 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 22 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 23 * OTHER DEALINGS IN THE SOFTWARE. 24 */ 25 26 #ifndef DRM_MODESET_LOCK_H_ 27 #define DRM_MODESET_LOCK_H_ 28 29 #include <linux/ww_mutex.h> 30 31 struct drm_modeset_lock; 32 33 /** 34 * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx) 35 * @ww_ctx: base acquire ctx 36 * @contended: used internally for -EDEADLK handling 37 * @locked: list of held locks 38 * @trylock_only: trylock mode used in atomic contexts/panic notifiers 39 * @interruptible: whether interruptible locking should be used. 40 * 41 * Each thread competing for a set of locks must use one acquire 42 * ctx. And if any lock fxn returns -EDEADLK, it must backoff and 43 * retry. 44 */ 45 struct drm_modeset_acquire_ctx { 46 47 struct ww_acquire_ctx ww_ctx; 48 49 /* 50 * Contended lock: if a lock is contended you should only call 51 * drm_modeset_backoff() which drops locks and slow-locks the 52 * contended lock. 53 */ 54 struct drm_modeset_lock *contended; 55 56 /* 57 * list of held locks (drm_modeset_lock) 58 */ 59 struct list_head locked; 60 61 /* 62 * Trylock mode, use only for panic handlers! 63 */ 64 bool trylock_only; 65 66 /* Perform interruptible waits on this context. */ 67 bool interruptible; 68 }; 69 70 /** 71 * struct drm_modeset_lock - used for locking modeset resources. 72 * @mutex: resource locking 73 * @head: used to hold its place on &drm_atomi_state.locked list when 74 * part of an atomic update 75 * 76 * Used for locking CRTCs and other modeset resources. 77 */ 78 struct drm_modeset_lock { 79 /* 80 * modeset lock 81 */ 82 struct ww_mutex mutex; 83 84 /* 85 * Resources that are locked as part of an atomic update are added 86 * to a list (so we know what to unlock at the end). 87 */ 88 struct list_head head; 89 }; 90 91 #define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0) 92 93 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx, 94 uint32_t flags); 95 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx); 96 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx); 97 int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx); 98 99 void drm_modeset_lock_init(struct drm_modeset_lock *lock); 100 101 /** 102 * drm_modeset_lock_fini - cleanup lock 103 * @lock: lock to cleanup 104 */ 105 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock) 106 { 107 WARN_ON(!list_empty(&lock->head)); 108 } 109 110 /** 111 * drm_modeset_is_locked - equivalent to mutex_is_locked() 112 * @lock: lock to check 113 */ 114 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock) 115 { 116 return ww_mutex_is_locked(&lock->mutex); 117 } 118 119 /** 120 * drm_modeset_lock_assert_held - equivalent to lockdep_assert_held() 121 * @lock: lock to check 122 */ 123 static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock) 124 { 125 lockdep_assert_held(&lock->mutex.base); 126 } 127 128 int drm_modeset_lock(struct drm_modeset_lock *lock, 129 struct drm_modeset_acquire_ctx *ctx); 130 int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock); 131 void drm_modeset_unlock(struct drm_modeset_lock *lock); 132 133 struct drm_device; 134 struct drm_crtc; 135 struct drm_plane; 136 137 void drm_modeset_lock_all(struct drm_device *dev); 138 void drm_modeset_unlock_all(struct drm_device *dev); 139 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev); 140 141 int drm_modeset_lock_all_ctx(struct drm_device *dev, 142 struct drm_modeset_acquire_ctx *ctx); 143 144 /** 145 * DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks 146 * @dev: drm device 147 * @ctx: local modeset acquire context, will be dereferenced 148 * @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init() 149 * @ret: local ret/err/etc variable to track error status 150 * 151 * Use these macros to simplify grabbing all modeset locks using a local 152 * context. This has the advantage of reducing boilerplate, but also properly 153 * checking return values where appropriate. 154 * 155 * Any code run between BEGIN and END will be holding the modeset locks. 156 * 157 * This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and 158 * forth between the labels on deadlock and error conditions. 159 * 160 * Drivers can acquire additional modeset locks. If any lock acquisition 161 * fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with 162 * the @ret parameter containing the return value of drm_modeset_lock(). 163 * 164 * Returns: 165 * The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN() 166 * is 0, so no error checking is necessary 167 */ 168 #define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret) \ 169 drm_modeset_acquire_init(&ctx, flags); \ 170 modeset_lock_retry: \ 171 ret = drm_modeset_lock_all_ctx(dev, &ctx); \ 172 if (ret) \ 173 goto modeset_lock_fail; 174 175 /** 176 * DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks 177 * @ctx: local modeset acquire context, will be dereferenced 178 * @ret: local ret/err/etc variable to track error status 179 * 180 * The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN 181 * if ret is -EDEADLK. 182 * 183 * It's important that you use the same ret variable for begin and end so 184 * deadlock conditions are properly handled. 185 * 186 * Returns: 187 * ret will be untouched unless it is -EDEADLK on entry. That means that if you 188 * successfully acquire the locks, ret will be whatever your code sets it to. If 189 * there is a deadlock or other failure with acquire or backoff, ret will be set 190 * to that failure. In both of these cases the code between BEGIN/END will not 191 * be run, so the failure will reflect the inability to grab the locks. 192 */ 193 #define DRM_MODESET_LOCK_ALL_END(ctx, ret) \ 194 modeset_lock_fail: \ 195 if (ret == -EDEADLK) { \ 196 ret = drm_modeset_backoff(&ctx); \ 197 if (!ret) \ 198 goto modeset_lock_retry; \ 199 } \ 200 drm_modeset_drop_locks(&ctx); \ 201 drm_modeset_acquire_fini(&ctx); 202 203 #endif /* DRM_MODESET_LOCK_H_ */ 204
Indexes created Wed Oct 22 13:09:56 GMT 2025