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 #ifdef CONFIG_DEBUG_MUTEXES 82 void dma_resv_reset_shared_max(struct dma_resv *obj); 83 #else 84 static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {} 85 #endif 86 87 /** 88 * dma_resv_lock - lock the reservation object 89 * @obj: the reservation object 90 * @ctx: the locking context 91 * 92 * Locks the reservation object for exclusive access and modification. Note, 93 * that the lock is only against other writers, readers will run concurrently 94 * with a writer under RCU. The seqlock is used to notify readers if they 95 * overlap with a writer. 96 * 97 * As the reservation object may be locked by multiple parties in an 98 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 99 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 100 * object may be locked by itself by passing NULL as @ctx. 101 */ 102 static inline int dma_resv_lock(struct dma_resv *obj, 103 struct ww_acquire_ctx *ctx) 104 { 105 return ww_mutex_lock(&obj->lock, ctx); 106 } 107 108 /** 109 * dma_resv_lock_interruptible - lock the reservation object 110 * @obj: the reservation object 111 * @ctx: the locking context 112 * 113 * Locks the reservation object interruptible for exclusive access and 114 * modification. Note, that the lock is only against other writers, readers 115 * will run concurrently with a writer under RCU. The seqlock is used to 116 * notify readers if they overlap with a writer. 117 * 118 * As the reservation object may be locked by multiple parties in an 119 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 120 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 121 * object may be locked by itself by passing NULL as @ctx. 122 */ 123 static inline int dma_resv_lock_interruptible(struct dma_resv *obj, 124 struct ww_acquire_ctx *ctx) 125 { 126 return ww_mutex_lock_interruptible(&obj->lock, ctx); 127 } 128 129 /** 130 * dma_resv_lock_slow - slowpath lock the reservation object 131 * @obj: the reservation object 132 * @ctx: the locking context 133 * 134 * Acquires the reservation object after a die case. This function 135 * will sleep until the lock becomes available. See dma_resv_lock() as 136 * well. 137 */ 138 static inline void dma_resv_lock_slow(struct dma_resv *obj, 139 struct ww_acquire_ctx *ctx) 140 { 141 ww_mutex_lock_slow(&obj->lock, ctx); 142 } 143 144 /** 145 * dma_resv_lock_slow_interruptible - slowpath lock the reservation 146 * object, interruptible 147 * @obj: the reservation object 148 * @ctx: the locking context 149 * 150 * Acquires the reservation object interruptible after a die case. This function 151 * will sleep until the lock becomes available. See 152 * dma_resv_lock_interruptible() as well. 153 */ 154 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj, 155 struct ww_acquire_ctx *ctx) 156 { 157 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx); 158 } 159 160 /** 161 * dma_resv_trylock - trylock the reservation object 162 * @obj: the reservation object 163 * 164 * Tries to lock the reservation object for exclusive access and modification. 165 * Note, that the lock is only against other writers, readers will run 166 * concurrently with a writer under RCU. The seqlock is used to notify readers 167 * if they overlap with a writer. 168 * 169 * Also note that since no context is provided, no deadlock protection is 170 * possible. 171 * 172 * Returns true if the lock was acquired, false otherwise. 173 */ 174 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj) 175 { 176 return ww_mutex_trylock(&obj->lock); 177 } 178 179 /** 180 * dma_resv_is_locked - is the reservation object locked 181 * @obj: the reservation object 182 * 183 * Returns true if the mutex is locked, false if unlocked. 184 */ 185 static inline bool dma_resv_is_locked(struct dma_resv *obj) 186 { 187 return ww_mutex_is_locked(&obj->lock); 188 } 189 190 /** 191 * dma_resv_locking_ctx - returns the context used to lock the object 192 * @obj: the reservation object 193 * 194 * Returns the context used to lock a reservation object or NULL if no context 195 * was used or the object is not locked at all. 196 */ 197 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj) 198 { 199 return READ_ONCE(obj->lock.ctx); 200 } 201 202 /** 203 * dma_resv_unlock - unlock the reservation object 204 * @obj: the reservation object 205 * 206 * Unlocks the reservation object following exclusive access. 207 */ 208 static inline void dma_resv_unlock(struct dma_resv *obj) 209 { 210 dma_resv_reset_shared_max(obj); 211 ww_mutex_unlock(&obj->lock); 212 } 213 214 /** 215 * dma_resv_excl_fence - return the object's exclusive fence 216 * @obj: the reservation object 217 * 218 * Returns the exclusive fence (if any). Caller must either hold the objects 219 * through dma_resv_lock() or the RCU read side lock through rcu_read_lock(), 220 * or one of the variants of each 221 * 222 * RETURNS 223 * The exclusive fence or NULL 224 */ 225 static inline struct dma_fence * 226 dma_resv_excl_fence(struct dma_resv *obj) 227 { 228 return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj)); 229 } 230 231 /** 232 * dma_resv_get_excl_unlocked - get the reservation object's 233 * exclusive fence, without lock held. 234 * @obj: the reservation object 235 * 236 * If there is an exclusive fence, this atomically increments it's 237 * reference count and returns it. 238 * 239 * RETURNS 240 * The exclusive fence or NULL if none 241 */ 242 static inline struct dma_fence * 243 dma_resv_get_excl_unlocked(struct dma_resv *obj) 244 { 245 struct dma_fence *fence; 246 247 if (!rcu_access_pointer(obj->fence_excl)) 248 return NULL; 249 250 rcu_read_lock(); 251 fence = dma_fence_get_rcu_safe(&obj->fence_excl); 252 rcu_read_unlock(); 253 254 return fence; 255 } 256 257 /** 258 * dma_resv_shared_list - get the reservation object's shared fence list 259 * @obj: the reservation object 260 * 261 * Returns the shared fence list. Caller must either hold the objects 262 * through dma_resv_lock() or the RCU read side lock through rcu_read_lock(), 263 * or one of the variants of each 264 */ 265 static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj) 266 { 267 return rcu_dereference_check(obj->fence, dma_resv_held(obj)); 268 } 269 270 void dma_resv_init(struct dma_resv *obj); 271 void dma_resv_fini(struct dma_resv *obj); 272 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences); 273 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence); 274 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence); 275 int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl, 276 unsigned *pshared_count, struct dma_fence ***pshared); 277 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src); 278 long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr, 279 unsigned long timeout); 280 bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all); 281 282 #endif /* _LINUX_RESERVATION_H */ 283