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 extern struct lock_class_key reservation_seqcount_class;
  50 extern const char reservation_seqcount_string[];
  51
  52 /**
  53  * struct dma_resv_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 dma_resv_list {
  60         struct rcu_head rcu;
  61         u32 shared_count, shared_max;
  62         struct dma_fence __rcu *shared[];
  63 };
  64
  65 /**
  66  * struct dma_resv - 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  */
  72 struct dma_resv {
  73         struct ww_mutex lock;
  74         seqcount_t seq;
  75
  76         struct dma_fence __rcu *fence_excl;
  77         struct dma_resv_list __rcu *fence;
  78 };
  79
  80 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
  81 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
  82
  83 /**
  84  * dma_resv_get_list - get the reservation object's
  85  * shared fence list, with update-side lock held
  86  * @obj: the reservation object
  87  *
  88  * Returns the shared fence list.  Does NOT take references to
  89  * the fence.  The obj->lock must be held.
  90  */
  91 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
  92 {
  93         return rcu_dereference_protected(obj->fence,
  94                                          dma_resv_held(obj));
  95 }
  96
  97 /**
  98  * dma_resv_lock - lock the reservation object
  99  * @obj: the reservation object
 100  * @ctx: the locking context
 101  *
 102  * Locks the reservation object for exclusive access and modification. Note,
 103  * that the lock is only against other writers, readers will run concurrently
 104  * with a writer under RCU. The seqlock is used to notify readers if they
 105  * overlap with a writer.
 106  *
 107  * As the reservation object may be locked by multiple parties in an
 108  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
 109  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
 110  * object may be locked by itself by passing NULL as @ctx.
 111  */
 112 static inline int dma_resv_lock(struct dma_resv *obj,
 113                                 struct ww_acquire_ctx *ctx)
 114 {
 115         return ww_mutex_lock(&obj->lock, ctx);
 116 }
 117
 118 /**
 119  * dma_resv_lock_interruptible - lock the reservation object
 120  * @obj: the reservation object
 121  * @ctx: the locking context
 122  *
 123  * Locks the reservation object interruptible for exclusive access and
 124  * modification. Note, that the lock is only against other writers, readers
 125  * will run concurrently with a writer under RCU. The seqlock is used to
 126  * notify readers if they overlap with a writer.
 127  *
 128  * As the reservation object may be locked by multiple parties in an
 129  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
 130  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
 131  * object may be locked by itself by passing NULL as @ctx.
 132  */
 133 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
 134                                               struct ww_acquire_ctx *ctx)
 135 {
 136         return ww_mutex_lock_interruptible(&obj->lock, ctx);
 137 }
 138
 139 /**
 140  * dma_resv_lock_slow - slowpath lock the reservation object
 141  * @obj: the reservation object
 142  * @ctx: the locking context
 143  *
 144  * Acquires the reservation object after a die case. This function
 145  * will sleep until the lock becomes available. See dma_resv_lock() as
 146  * well.
 147  */
 148 static inline void dma_resv_lock_slow(struct dma_resv *obj,
 149                                       struct ww_acquire_ctx *ctx)
 150 {
 151         ww_mutex_lock_slow(&obj->lock, ctx);
 152 }
 153
 154 /**
 155  * dma_resv_lock_slow_interruptible - slowpath lock the reservation
 156  * object, interruptible
 157  * @obj: the reservation object
 158  * @ctx: the locking context
 159  *
 160  * Acquires the reservation object interruptible after a die case. This function
 161  * will sleep until the lock becomes available. See
 162  * dma_resv_lock_interruptible() as well.
 163  */
 164 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
 165                                                    struct ww_acquire_ctx *ctx)
 166 {
 167         return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
 168 }
 169
 170 /**
 171  * dma_resv_trylock - trylock the reservation object
 172  * @obj: the reservation object
 173  *
 174  * Tries to lock the reservation object for exclusive access and modification.
 175  * Note, that the lock is only against other writers, readers will run
 176  * concurrently with a writer under RCU. The seqlock is used to notify readers
 177  * if they overlap with a writer.
 178  *
 179  * Also note that since no context is provided, no deadlock protection is
 180  * possible.
 181  *
 182  * Returns true if the lock was acquired, false otherwise.
 183  */
 184 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
 185 {
 186         return ww_mutex_trylock(&obj->lock);
 187 }
 188
 189 /**
 190  * dma_resv_is_locked - is the reservation object locked
 191  * @obj: the reservation object
 192  *
 193  * Returns true if the mutex is locked, false if unlocked.
 194  */
 195 static inline bool dma_resv_is_locked(struct dma_resv *obj)
 196 {
 197         return ww_mutex_is_locked(&obj->lock);
 198 }
 199
 200 /**
 201  * dma_resv_locking_ctx - returns the context used to lock the object
 202  * @obj: the reservation object
 203  *
 204  * Returns the context used to lock a reservation object or NULL if no context
 205  * was used or the object is not locked at all.
 206  */
 207 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
 208 {
 209         return READ_ONCE(obj->lock.ctx);
 210 }
 211
 212 /**
 213  * dma_resv_unlock - unlock the reservation object
 214  * @obj: the reservation object
 215  *
 216  * Unlocks the reservation object following exclusive access.
 217  */
 218 static inline void dma_resv_unlock(struct dma_resv *obj)
 219 {
 220 #ifdef CONFIG_DEBUG_MUTEXES
 221         /* Test shared fence slot reservation */
 222         if (rcu_access_pointer(obj->fence)) {
 223                 struct dma_resv_list *fence = dma_resv_get_list(obj);
 224
 225                 fence->shared_max = fence->shared_count;
 226         }
 227 #endif
 228         ww_mutex_unlock(&obj->lock);
 229 }
 230
 231 /**
 232  * dma_resv_get_excl - get the reservation object's
 233  * exclusive fence, with update-side lock held
 234  * @obj: the reservation object
 235  *
 236  * Returns the exclusive fence (if any).  Does NOT take a
 237  * reference. Writers must hold obj->lock, readers may only
 238  * hold a RCU read side lock.
 239  *
 240  * RETURNS
 241  * The exclusive fence or NULL
 242  */
 243 static inline struct dma_fence *
 244 dma_resv_get_excl(struct dma_resv *obj)
 245 {
 246         return rcu_dereference_protected(obj->fence_excl,
 247                                          dma_resv_held(obj));
 248 }
 249
 250 /**
 251  * dma_resv_get_excl_rcu - get the reservation object's
 252  * exclusive fence, without lock held.
 253  * @obj: the reservation object
 254  *
 255  * If there is an exclusive fence, this atomically increments it's
 256  * reference count and returns it.
 257  *
 258  * RETURNS
 259  * The exclusive fence or NULL if none
 260  */
 261 static inline struct dma_fence *
 262 dma_resv_get_excl_rcu(struct dma_resv *obj)
 263 {
 264         struct dma_fence *fence;
 265
 266         if (!rcu_access_pointer(obj->fence_excl))
 267                 return NULL;
 268
 269         rcu_read_lock();
 270         fence = dma_fence_get_rcu_safe(&obj->fence_excl);
 271         rcu_read_unlock();
 272
 273         return fence;
 274 }
 275
 276 void dma_resv_init(struct dma_resv *obj);
 277 void dma_resv_fini(struct dma_resv *obj);
 278 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 279 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 280
 281 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
 282
 283 int dma_resv_get_fences_rcu(struct dma_resv *obj,
 284                             struct dma_fence **pfence_excl,
 285                             unsigned *pshared_count,
 286                             struct dma_fence ***pshared);
 287
 288 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
 289
 290 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
 291                                unsigned long timeout);
 292
 293 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);
 294
 295 #endif /* _LINUX_RESERVATION_H */