include/linux/reservation.h

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