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27 /*
28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29  */
30 /** @file ttm_object.h
31  *
32  * Base- and reference object implementation for the various
33  * ttm objects. Implements reference counting, minimal security checks
34  * and release on file close.
35  */
36 
37 #ifndef _TTM_OBJECT_H_
38 #define _TTM_OBJECT_H_
39 
40 #include <linux/list.h>
41 #include <drm/drm_hashtab.h>
42 #include <linux/kref.h>
43 #include <linux/rcupdate.h>
44 #include <linux/dma-buf.h>
45 #include <drm/ttm/ttm_memory.h>
46 
47 /**
48  * enum ttm_ref_type
49  *
50  * Describes what type of reference a ref object holds.
51  *
52  * TTM_REF_USAGE is a simple refcount on a base object.
53  *
54  * TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
55  * buffer object.
56  *
57  * TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
58  * buffer object.
59  *
60  */
61 
62 enum ttm_ref_type {
63 	TTM_REF_USAGE,
64 	TTM_REF_SYNCCPU_READ,
65 	TTM_REF_SYNCCPU_WRITE,
66 	TTM_REF_NUM
67 };
68 
69 /**
70  * enum ttm_object_type
71  *
72  * One entry per ttm object type.
73  * Device-specific types should use the
74  * ttm_driver_typex types.
75  */
76 
77 enum ttm_object_type {
78 	ttm_fence_type,
79 	ttm_buffer_type,
80 	ttm_lock_type,
81 	ttm_prime_type,
82 	ttm_driver_type0 = 256,
83 	ttm_driver_type1,
84 	ttm_driver_type2,
85 	ttm_driver_type3,
86 	ttm_driver_type4,
87 	ttm_driver_type5
88 };
89 
90 struct ttm_object_file;
91 struct ttm_object_device;
92 
93 /**
94  * struct ttm_base_object
95  *
96  * @hash: hash entry for the per-device object hash.
97  * @type: derived type this object is base class for.
98  * @shareable: Other ttm_object_files can access this object.
99  *
100  * @tfile: Pointer to ttm_object_file of the creator.
101  * NULL if the object was not created by a user request.
102  * (kernel object).
103  *
104  * @refcount: Number of references to this object, not
105  * including the hash entry. A reference to a base object can
106  * only be held by a ref object.
107  *
108  * @refcount_release: A function to be called when there are
109  * no more references to this object. This function should
110  * destroy the object (or make sure destruction eventually happens),
111  * and when it is called, the object has
112  * already been taken out of the per-device hash. The parameter
113  * "base" should be set to NULL by the function.
114  *
115  * @ref_obj_release: A function to be called when a reference object
116  * with another ttm_ref_type than TTM_REF_USAGE is deleted.
117  * This function may, for example, release a lock held by a user-space
118  * process.
119  *
120  * This struct is intended to be used as a base struct for objects that
121  * are visible to user-space. It provides a global name, race-safe
122  * access and refcounting, minimal access contol and hooks for unref actions.
123  */
124 
125 struct ttm_base_object {
126 	struct rcu_head rhead;
127 	struct ttm_object_file *tfile;
128 	struct kref refcount;
129 	void (*refcount_release) (struct ttm_base_object **base);
130 	void (*ref_obj_release) (struct ttm_base_object *base,
131 				 enum ttm_ref_type ref_type);
132 	u32 handle;
133 	enum ttm_object_type object_type;
134 	u32 shareable;
135 };
136 
137 
138 /**
139  * struct ttm_prime_object - Modified base object that is prime-aware
140  *
141  * @base: struct ttm_base_object that we derive from
142  * @mutex: Mutex protecting the @dma_buf member.
143  * @size: Size of the dma_buf associated with this object
144  * @real_type: Type of the underlying object. Needed since we're setting
145  * the value of @base::object_type to ttm_prime_type
146  * @dma_buf: Non ref-coutned pointer to a struct dma_buf created from this
147  * object.
148  * @refcount_release: The underlying object's release method. Needed since
149  * we set @base::refcount_release to our own release method.
150  */
151 
152 struct ttm_prime_object {
153 	struct ttm_base_object base;
154 	struct mutex mutex;
155 	size_t size;
156 	enum ttm_object_type real_type;
157 	struct dma_buf *dma_buf;
158 	void (*refcount_release) (struct ttm_base_object **);
159 };
160 
161 /**
162  * ttm_base_object_init
163  *
164  * @tfile: Pointer to a struct ttm_object_file.
165  * @base: The struct ttm_base_object to initialize.
166  * @shareable: This object is shareable with other applcations.
167  * (different @tfile pointers.)
168  * @type: The object type.
169  * @refcount_release: See the struct ttm_base_object description.
170  * @ref_obj_release: See the struct ttm_base_object description.
171  *
172  * Initializes a struct ttm_base_object.
173  */
174 
175 extern int ttm_base_object_init(struct ttm_object_file *tfile,
176 				struct ttm_base_object *base,
177 				bool shareable,
178 				enum ttm_object_type type,
179 				void (*refcount_release) (struct ttm_base_object
180 							  **),
181 				void (*ref_obj_release) (struct ttm_base_object
182 							 *,
183 							 enum ttm_ref_type
184 							 ref_type));
185 
186 /**
187  * ttm_base_object_lookup
188  *
189  * @tfile: Pointer to a struct ttm_object_file.
190  * @key: Hash key
191  *
192  * Looks up a struct ttm_base_object with the key @key.
193  */
194 
195 extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
196 						      *tfile, uint32_t key);
197 
198 /**
199  * ttm_base_object_lookup_for_ref
200  *
201  * @tdev: Pointer to a struct ttm_object_device.
202  * @key: Hash key
203  *
204  * Looks up a struct ttm_base_object with the key @key.
205  * This function should only be used when the struct tfile associated with the
206  * caller doesn't yet have a reference to the base object.
207  */
208 
209 extern struct ttm_base_object *
210 ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key);
211 
212 /**
213  * ttm_base_object_unref
214  *
215  * @p_base: Pointer to a pointer referencing a struct ttm_base_object.
216  *
217  * Decrements the base object refcount and clears the pointer pointed to by
218  * p_base.
219  */
220 
221 extern void ttm_base_object_unref(struct ttm_base_object **p_base);
222 
223 /**
224  * ttm_ref_object_add.
225  *
226  * @tfile: A struct ttm_object_file representing the application owning the
227  * ref_object.
228  * @base: The base object to reference.
229  * @ref_type: The type of reference.
230  * @existed: Upon completion, indicates that an identical reference object
231  * already existed, and the refcount was upped on that object instead.
232  * @require_existed: Fail with -EPERM if an identical ref object didn't
233  * already exist.
234  *
235  * Checks that the base object is shareable and adds a ref object to it.
236  *
237  * Adding a ref object to a base object is basically like referencing the
238  * base object, but a user-space application holds the reference. When the
239  * file corresponding to @tfile is closed, all its reference objects are
240  * deleted. A reference object can have different types depending on what
241  * it's intended for. It can be refcounting to prevent object destruction,
242  * When user-space takes a lock, it can add a ref object to that lock to
243  * make sure the lock is released if the application dies. A ref object
244  * will hold a single reference on a base object.
245  */
246 extern int ttm_ref_object_add(struct ttm_object_file *tfile,
247 			      struct ttm_base_object *base,
248 			      enum ttm_ref_type ref_type, bool *existed,
249 			      bool require_existed);
250 
251 extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,
252 				  struct ttm_base_object *base);
253 
254 /**
255  * ttm_ref_object_base_unref
256  *
257  * @key: Key representing the base object.
258  * @ref_type: Ref type of the ref object to be dereferenced.
259  *
260  * Unreference a ref object with type @ref_type
261  * on the base object identified by @key. If there are no duplicate
262  * references, the ref object will be destroyed and the base object
263  * will be unreferenced.
264  */
265 extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
266 				     unsigned long key,
267 				     enum ttm_ref_type ref_type);
268 
269 /**
270  * ttm_object_file_init - initialize a struct ttm_object file
271  *
272  * @tdev: A struct ttm_object device this file is initialized on.
273  * @hash_order: Order of the hash table used to hold the reference objects.
274  *
275  * This is typically called by the file_ops::open function.
276  */
277 
278 extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
279 						    *tdev,
280 						    unsigned int hash_order);
281 
282 /**
283  * ttm_object_file_release - release data held by a ttm_object_file
284  *
285  * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
286  * *p_tfile will be set to NULL by this function.
287  *
288  * Releases all data associated by a ttm_object_file.
289  * Typically called from file_ops::release. The caller must
290  * ensure that there are no concurrent users of tfile.
291  */
292 
293 extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
294 
295 /**
296  * ttm_object device init - initialize a struct ttm_object_device
297  *
298  * @mem_glob: struct ttm_mem_global for memory accounting.
299  * @hash_order: Order of hash table used to hash the base objects.
300  * @ops: DMA buf ops for prime objects of this device.
301  *
302  * This function is typically called on device initialization to prepare
303  * data structures needed for ttm base and ref objects.
304  */
305 
306 extern struct ttm_object_device *
307 ttm_object_device_init(struct ttm_mem_global *mem_glob,
308 		       unsigned int hash_order,
309 		       const struct dma_buf_ops *ops);
310 
311 /**
312  * ttm_object_device_release - release data held by a ttm_object_device
313  *
314  * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
315  * *p_tdev will be set to NULL by this function.
316  *
317  * Releases all data associated by a ttm_object_device.
318  * Typically called from driver::unload before the destruction of the
319  * device private data structure.
320  */
321 
322 extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
323 
324 #define ttm_base_object_kfree(__object, __base)\
325 	kfree_rcu(__object, __base.rhead)
326 
327 extern int ttm_prime_object_init(struct ttm_object_file *tfile,
328 				 size_t size,
329 				 struct ttm_prime_object *prime,
330 				 bool shareable,
331 				 enum ttm_object_type type,
332 				 void (*refcount_release)
333 				 (struct ttm_base_object **),
334 				 void (*ref_obj_release)
335 				 (struct ttm_base_object *,
336 				  enum ttm_ref_type ref_type));
337 
338 static inline enum ttm_object_type
339 ttm_base_object_type(struct ttm_base_object *base)
340 {
341 	return (base->object_type == ttm_prime_type) ?
342 		container_of(base, struct ttm_prime_object, base)->real_type :
343 		base->object_type;
344 }
345 extern int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
346 				  int fd, u32 *handle);
347 extern int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
348 				  uint32_t handle, uint32_t flags,
349 				  int *prime_fd);
350 
351 #define ttm_prime_object_kfree(__obj, __prime)		\
352 	kfree_rcu(__obj, __prime.base.rhead)
353 
354 /*
355  * Extra memory required by the base object's idr storage, which is allocated
356  * separately from the base object itself. We estimate an on-average 128 bytes
357  * per idr.
358  */
359 #define TTM_OBJ_EXTRA_SIZE 128
360 
361 struct ttm_base_object *
362 ttm_base_object_noref_lookup(struct ttm_object_file *tfile, uint32_t key);
363 
364 /**
365  * ttm_base_object_noref_release - release a base object pointer looked up
366  * without reference
367  *
368  * Releases a base object pointer looked up with ttm_base_object_noref_lookup().
369  */
370 static inline void ttm_base_object_noref_release(void)
371 {
372 	__acquire(RCU);
373 	rcu_read_unlock();
374 }
375 #endif
376