include/linux/dma-resv.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
  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 */