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