1 /* 2 * Header file for reservations for dma-buf and ttm 3 * 4 * Copyright(C) 2011 Linaro Limited. All rights reserved. 5 * Copyright (C) 2012-2013 Canonical Ltd 6 * Copyright (C) 2012 Texas Instruments 7 * 8 * Authors: 9 * Rob Clark <robdclark@gmail.com> 10 * Maarten Lankhorst <maarten.lankhorst@canonical.com> 11 * Thomas Hellstrom <thellstrom-at-vmware-dot-com> 12 * 13 * Based on bo.c which bears the following copyright notice, 14 * but is dual licensed: 15 * 16 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA 17 * All Rights Reserved. 18 * 19 * Permission is hereby granted, free of charge, to any person obtaining a 20 * copy of this software and associated documentation files (the 21 * "Software"), to deal in the Software without restriction, including 22 * without limitation the rights to use, copy, modify, merge, publish, 23 * distribute, sub license, and/or sell copies of the Software, and to 24 * permit persons to whom the Software is furnished to do so, subject to 25 * the following conditions: 26 * 27 * The above copyright notice and this permission notice (including the 28 * next paragraph) shall be included in all copies or substantial portions 29 * of the Software. 30 * 31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 32 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 33 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL 34 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, 35 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 36 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 37 * USE OR OTHER DEALINGS IN THE SOFTWARE. 38 */ 39 #ifndef _LINUX_RESERVATION_H 40 #define _LINUX_RESERVATION_H 41 42 #include <linux/ww_mutex.h> 43 #include <linux/dma-fence.h> 44 #include <linux/slab.h> 45 #include <linux/seqlock.h> 46 #include <linux/rcupdate.h> 47 48 extern struct ww_class reservation_ww_class; 49 50 /** 51 * struct dma_resv_list - a list of shared fences 52 * @rcu: for internal use 53 * @shared_count: table of shared fences 54 * @shared_max: for growing shared fence table 55 * @shared: shared fence table 56 */ 57 struct dma_resv_list { 58 struct rcu_head rcu; 59 u32 shared_count, shared_max; 60 struct dma_fence __rcu *shared[]; 61 }; 62 63 /** 64 * struct dma_resv - a reservation object manages fences for a buffer 65 * @lock: update side lock 66 * @seq: sequence count for managing RCU read-side synchronization 67 * @fence_excl: the exclusive fence, if there is one currently 68 * @fence: list of current shared fences 69 */ 70 struct dma_resv { 71 struct ww_mutex lock; 72 seqcount_ww_mutex_t seq; 73 74 struct dma_fence __rcu *fence_excl; 75 struct dma_resv_list __rcu *fence; 76 }; 77 78 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base) 79 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base) 80 81 /** 82 * dma_resv_get_list - get the reservation object's 83 * shared fence list, with update-side lock held 84 * @obj: the reservation object 85 * 86 * Returns the shared fence list. Does NOT take references to 87 * the fence. The obj->lock must be held. 88 */ 89 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj) 90 { 91 return rcu_dereference_protected(obj->fence, 92 dma_resv_held(obj)); 93 } 94 95 /** 96 * dma_resv_lock - lock the reservation object 97 * @obj: the reservation object 98 * @ctx: the locking context 99 * 100 * Locks the reservation object for exclusive access and modification. Note, 101 * that the lock is only against other writers, readers will run concurrently 102 * with a writer under RCU. The seqlock is used to notify readers if they 103 * overlap with a writer. 104 * 105 * As the reservation object may be locked by multiple parties in an 106 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 107 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 108 * object may be locked by itself by passing NULL as @ctx. 109 */ 110 static inline int dma_resv_lock(struct dma_resv *obj, 111 struct ww_acquire_ctx *ctx) 112 { 113 return ww_mutex_lock(&obj->lock, ctx); 114 } 115 116 /** 117 * dma_resv_lock_interruptible - lock the reservation object 118 * @obj: the reservation object 119 * @ctx: the locking context 120 * 121 * Locks the reservation object interruptible for exclusive access and 122 * modification. Note, that the lock is only against other writers, readers 123 * will run concurrently with a writer under RCU. The seqlock is used to 124 * notify readers if they overlap with a writer. 125 * 126 * As the reservation object may be locked by multiple parties in an 127 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 128 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 129 * object may be locked by itself by passing NULL as @ctx. 130 */ 131 static inline int dma_resv_lock_interruptible(struct dma_resv *obj, 132 struct ww_acquire_ctx *ctx) 133 { 134 return ww_mutex_lock_interruptible(&obj->lock, ctx); 135 } 136 137 /** 138 * dma_resv_lock_slow - slowpath lock the reservation object 139 * @obj: the reservation object 140 * @ctx: the locking context 141 * 142 * Acquires the reservation object after a die case. This function 143 * will sleep until the lock becomes available. See dma_resv_lock() as 144 * well. 145 */ 146 static inline void dma_resv_lock_slow(struct dma_resv *obj, 147 struct ww_acquire_ctx *ctx) 148 { 149 ww_mutex_lock_slow(&obj->lock, ctx); 150 } 151 152 /** 153 * dma_resv_lock_slow_interruptible - slowpath lock the reservation 154 * object, interruptible 155 * @obj: the reservation object 156 * @ctx: the locking context 157 * 158 * Acquires the reservation object interruptible after a die case. This function 159 * will sleep until the lock becomes available. See 160 * dma_resv_lock_interruptible() as well. 161 */ 162 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj, 163 struct ww_acquire_ctx *ctx) 164 { 165 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx); 166 } 167 168 /** 169 * dma_resv_trylock - trylock the reservation object 170 * @obj: the reservation object 171 * 172 * Tries to lock the reservation object for exclusive access and modification. 173 * Note, that the lock is only against other writers, readers will run 174 * concurrently with a writer under RCU. The seqlock is used to notify readers 175 * if they overlap with a writer. 176 * 177 * Also note that since no context is provided, no deadlock protection is 178 * possible. 179 * 180 * Returns true if the lock was acquired, false otherwise. 181 */ 182 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj) 183 { 184 return ww_mutex_trylock(&obj->lock); 185 } 186 187 /** 188 * dma_resv_is_locked - is the reservation object locked 189 * @obj: the reservation object 190 * 191 * Returns true if the mutex is locked, false if unlocked. 192 */ 193 static inline bool dma_resv_is_locked(struct dma_resv *obj) 194 { 195 return ww_mutex_is_locked(&obj->lock); 196 } 197 198 /** 199 * dma_resv_locking_ctx - returns the context used to lock the object 200 * @obj: the reservation object 201 * 202 * Returns the context used to lock a reservation object or NULL if no context 203 * was used or the object is not locked at all. 204 */ 205 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj) 206 { 207 return READ_ONCE(obj->lock.ctx); 208 } 209 210 /** 211 * dma_resv_unlock - unlock the reservation object 212 * @obj: the reservation object 213 * 214 * Unlocks the reservation object following exclusive access. 215 */ 216 static inline void dma_resv_unlock(struct dma_resv *obj) 217 { 218 #ifdef CONFIG_DEBUG_MUTEXES 219 /* Test shared fence slot reservation */ 220 if (rcu_access_pointer(obj->fence)) { 221 struct dma_resv_list *fence = dma_resv_get_list(obj); 222 223 fence->shared_max = fence->shared_count; 224 } 225 #endif 226 ww_mutex_unlock(&obj->lock); 227 } 228 229 /** 230 * dma_resv_get_excl - get the reservation object's 231 * exclusive fence, with update-side lock held 232 * @obj: the reservation object 233 * 234 * Returns the exclusive fence (if any). Does NOT take a 235 * reference. Writers must hold obj->lock, readers may only 236 * hold a RCU read side lock. 237 * 238 * RETURNS 239 * The exclusive fence or NULL 240 */ 241 static inline struct dma_fence * 242 dma_resv_get_excl(struct dma_resv *obj) 243 { 244 return rcu_dereference_protected(obj->fence_excl, 245 dma_resv_held(obj)); 246 } 247 248 /** 249 * dma_resv_get_excl_rcu - get the reservation object's 250 * exclusive fence, without lock held. 251 * @obj: the reservation object 252 * 253 * If there is an exclusive fence, this atomically increments it's 254 * reference count and returns it. 255 * 256 * RETURNS 257 * The exclusive fence or NULL if none 258 */ 259 static inline struct dma_fence * 260 dma_resv_get_excl_rcu(struct dma_resv *obj) 261 { 262 struct dma_fence *fence; 263 264 if (!rcu_access_pointer(obj->fence_excl)) 265 return NULL; 266 267 rcu_read_lock(); 268 fence = dma_fence_get_rcu_safe(&obj->fence_excl); 269 rcu_read_unlock(); 270 271 return fence; 272 } 273 274 void dma_resv_init(struct dma_resv *obj); 275 void dma_resv_fini(struct dma_resv *obj); 276 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences); 277 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence); 278 279 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence); 280 281 int dma_resv_get_fences_rcu(struct dma_resv *obj, 282 struct dma_fence **pfence_excl, 283 unsigned *pshared_count, 284 struct dma_fence ***pshared); 285 286 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src); 287 288 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr, 289 unsigned long timeout); 290 291 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all); 292 293 #endif /* _LINUX_RESERVATION_H */ 294