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 48extern struct ww_class reservation_ww_class; 49extern struct lock_class_key reservation_seqcount_class; 50extern const char reservation_seqcount_string[]; 51 52/** 53 * struct reservation_object_list - a list of shared fences 54 * @rcu: for internal use 55 * @shared_count: table of shared fences 56 * @shared_max: for growing shared fence table 57 * @shared: shared fence table 58 */ 59struct reservation_object_list { 60 struct rcu_head rcu; 61 u32 shared_count, shared_max; 62 struct dma_fence __rcu *shared[]; 63}; 64 65/** 66 * struct reservation_object - a reservation object manages fences for a buffer 67 * @lock: update side lock 68 * @seq: sequence count for managing RCU read-side synchronization 69 * @fence_excl: the exclusive fence, if there is one currently 70 * @fence: list of current shared fences 71 */ 72struct reservation_object { 73 struct ww_mutex lock; 74 seqcount_t seq; 75 76 struct dma_fence __rcu *fence_excl; 77 struct reservation_object_list __rcu *fence; 78}; 79 80#define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base) 81#define reservation_object_assert_held(obj) \ 82 lockdep_assert_held(&(obj)->lock.base) 83 84/** 85 * reservation_object_init - initialize a reservation object 86 * @obj: the reservation object 87 */ 88static inline void 89reservation_object_init(struct reservation_object *obj) 90{ 91 ww_mutex_init(&obj->lock, &reservation_ww_class); 92 93 __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class); 94 RCU_INIT_POINTER(obj->fence, NULL); 95 RCU_INIT_POINTER(obj->fence_excl, NULL); 96} 97 98/** 99 * reservation_object_fini - destroys a reservation object 100 * @obj: the reservation object 101 */ 102static inline void 103reservation_object_fini(struct reservation_object *obj) 104{ 105 int i; 106 struct reservation_object_list *fobj; 107 struct dma_fence *excl; 108 109 /* 110 * This object should be dead and all references must have 111 * been released to it, so no need to be protected with rcu. 112 */ 113 excl = rcu_dereference_protected(obj->fence_excl, 1); 114 if (excl) 115 dma_fence_put(excl); 116 117 fobj = rcu_dereference_protected(obj->fence, 1); 118 if (fobj) { 119 for (i = 0; i < fobj->shared_count; ++i) 120 dma_fence_put(rcu_dereference_protected(fobj->shared[i], 1)); 121 122 kfree(fobj); 123 } 124 125 ww_mutex_destroy(&obj->lock); 126} 127 128/** 129 * reservation_object_get_list - get the reservation object's 130 * shared fence list, with update-side lock held 131 * @obj: the reservation object 132 * 133 * Returns the shared fence list. Does NOT take references to 134 * the fence. The obj->lock must be held. 135 */ 136static inline struct reservation_object_list * 137reservation_object_get_list(struct reservation_object *obj) 138{ 139 return rcu_dereference_protected(obj->fence, 140 reservation_object_held(obj)); 141} 142 143/** 144 * reservation_object_lock - lock the reservation object 145 * @obj: the reservation object 146 * @ctx: the locking context 147 * 148 * Locks the reservation object for exclusive access and modification. Note, 149 * that the lock is only against other writers, readers will run concurrently 150 * with a writer under RCU. The seqlock is used to notify readers if they 151 * overlap with a writer. 152 * 153 * As the reservation object may be locked by multiple parties in an 154 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 155 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 156 * object may be locked by itself by passing NULL as @ctx. 157 */ 158static inline int 159reservation_object_lock(struct reservation_object *obj, 160 struct ww_acquire_ctx *ctx) 161{ 162 return ww_mutex_lock(&obj->lock, ctx); 163} 164 165/** 166 * reservation_object_lock_interruptible - lock the reservation object 167 * @obj: the reservation object 168 * @ctx: the locking context 169 * 170 * Locks the reservation object interruptible for exclusive access and 171 * modification. Note, that the lock is only against other writers, readers 172 * will run concurrently with a writer under RCU. The seqlock is used to 173 * notify readers if they overlap with a writer. 174 * 175 * As the reservation object may be locked by multiple parties in an 176 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle 177 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation 178 * object may be locked by itself by passing NULL as @ctx. 179 */ 180static inline int 181reservation_object_lock_interruptible(struct reservation_object *obj, 182 struct ww_acquire_ctx *ctx) 183{ 184 return ww_mutex_lock_interruptible(&obj->lock, ctx); 185} 186 187 188/** 189 * reservation_object_trylock - trylock the reservation object 190 * @obj: the reservation object 191 * 192 * Tries to lock the reservation object for exclusive access and modification. 193 * Note, that the lock is only against other writers, readers will run 194 * concurrently with a writer under RCU. The seqlock is used to notify readers 195 * if they overlap with a writer. 196 * 197 * Also note that since no context is provided, no deadlock protection is 198 * possible. 199 * 200 * Returns true if the lock was acquired, false otherwise. 201 */ 202static inline bool __must_check 203reservation_object_trylock(struct reservation_object *obj) 204{ 205 return ww_mutex_trylock(&obj->lock); 206} 207 208/** 209 * reservation_object_unlock - unlock the reservation object 210 * @obj: the reservation object 211 * 212 * Unlocks the reservation object following exclusive access. 213 */ 214static inline void 215reservation_object_unlock(struct reservation_object *obj) 216{ 217#ifdef CONFIG_DEBUG_MUTEXES 218 /* Test shared fence slot reservation */ 219 if (obj->fence) 220 obj->fence->shared_max = obj->fence->shared_count; 221#endif 222 ww_mutex_unlock(&obj->lock); 223} 224 225/** 226 * reservation_object_get_excl - get the reservation object's 227 * exclusive fence, with update-side lock held 228 * @obj: the reservation object 229 * 230 * Returns the exclusive fence (if any). Does NOT take a 231 * reference. Writers must hold obj->lock, readers may only 232 * hold a RCU read side lock. 233 * 234 * RETURNS 235 * The exclusive fence or NULL 236 */ 237static inline struct dma_fence * 238reservation_object_get_excl(struct reservation_object *obj) 239{ 240 return rcu_dereference_protected(obj->fence_excl, 241 reservation_object_held(obj)); 242} 243 244/** 245 * reservation_object_get_excl_rcu - get the reservation object's 246 * exclusive fence, without lock held. 247 * @obj: the reservation object 248 * 249 * If there is an exclusive fence, this atomically increments it's 250 * reference count and returns it. 251 * 252 * RETURNS 253 * The exclusive fence or NULL if none 254 */ 255static inline struct dma_fence * 256reservation_object_get_excl_rcu(struct reservation_object *obj) 257{ 258 struct dma_fence *fence; 259 260 if (!rcu_access_pointer(obj->fence_excl)) 261 return NULL; 262 263 rcu_read_lock(); 264 fence = dma_fence_get_rcu_safe(&obj->fence_excl); 265 rcu_read_unlock(); 266 267 return fence; 268} 269 270int reservation_object_reserve_shared(struct reservation_object *obj, 271 unsigned int num_fences); 272void reservation_object_add_shared_fence(struct reservation_object *obj, 273 struct dma_fence *fence); 274 275void reservation_object_add_excl_fence(struct reservation_object *obj, 276 struct dma_fence *fence); 277 278int reservation_object_get_fences_rcu(struct reservation_object *obj, 279 struct dma_fence **pfence_excl, 280 unsigned *pshared_count, 281 struct dma_fence ***pshared); 282 283int reservation_object_copy_fences(struct reservation_object *dst, 284 struct reservation_object *src); 285 286long reservation_object_wait_timeout_rcu(struct reservation_object *obj, 287 bool wait_all, bool intr, 288 unsigned long timeout); 289 290bool reservation_object_test_signaled_rcu(struct reservation_object *obj, 291 bool test_all); 292 293#endif /* _LINUX_RESERVATION_H */ 294