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2024-05-10 093a6c67005148ae32a5c9e4553491b9f5c2457b 
 kernel/include/linux/dma-fence.h
....@@ -1,3 +1,4 @@
1
+/* SPDX-License-Identifier: GPL-2.0-only */
12 /*
23  * Fence mechanism for dma-buf to allow for asynchronous dma access
34  *
....@@ -7,15 +8,6 @@
78  * Authors:
89  * Rob Clark <robdclark@gmail.com>
910  * Maarten Lankhorst <maarten.lankhorst@canonical.com>
10
- *
11
- * This program is free software; you can redistribute it and/or modify it
12
- * under the terms of the GNU General Public License version 2 as published by
13
- * the Free Software Foundation.
14
- *
15
- * This program is distributed in the hope that it will be useful, but WITHOUT
16
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
18
- * more details.
1911  */
2012 
2113 #ifndef __LINUX_DMA_FENCE_H
....@@ -71,15 +63,35 @@
7163  * been completed, or never called at all.
7264  */
7365 struct dma_fence {
74
-	struct kref refcount;
75
-	const struct dma_fence_ops *ops;
76
-	struct rcu_head rcu;
77
-	struct list_head cb_list;
7866 	spinlock_t *lock;
67
+	const struct dma_fence_ops *ops;
68
+	/*
69
+	 * We clear the callback list on kref_put so that by the time we
70
+	 * release the fence it is unused. No one should be adding to the
71
+	 * cb_list that they don't themselves hold a reference for.
72
+	 *
73
+	 * The lifetime of the timestamp is similarly tied to both the
74
+	 * rcu freelist and the cb_list. The timestamp is only set upon
75
+	 * signaling while simultaneously notifying the cb_list. Ergo, we
76
+	 * only use either the cb_list of timestamp. Upon destruction,
77
+	 * neither are accessible, and so we can use the rcu. This means
78
+	 * that the cb_list is *only* valid until the signal bit is set,
79
+	 * and to read either you *must* hold a reference to the fence,
80
+	 * and not just the rcu_read_lock.
81
+	 *
82
+	 * Listed in chronological order.
83
+	 */
84
+	union {
85
+		struct list_head cb_list;
86
+		/* @cb_list replaced by @timestamp on dma_fence_signal() */
87
+		ktime_t timestamp;
88
+		/* @timestamp replaced by @rcu on dma_fence_release() */
89
+		struct rcu_head rcu;
90
+	};
7991 	u64 context;
80
-	unsigned seqno;
92
+	u64 seqno;
8193 	unsigned long flags;
82
-	ktime_t timestamp;
94
+	struct kref refcount;
8395 	int error;
8496 };
8597 
....@@ -111,6 +123,14 @@
111123  *
112124  */
113125 struct dma_fence_ops {
126
+	/**
127
+	 * @use_64bit_seqno:
128
+	 *
129
+	 * True if this dma_fence implementation uses 64bit seqno, false
130
+	 * otherwise.
131
+	 */
132
+	bool use_64bit_seqno;
133
+
114134 	/**
115135 	 * @get_driver_name:
116136 	 *
....@@ -244,7 +264,7 @@
244264 };
245265 
246266 void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
247
-		    spinlock_t *lock, u64 context, unsigned seqno);
267
+		    spinlock_t *lock, u64 context, u64 seqno);
248268 
249269 void dma_fence_release(struct kref *kref);
250270 void dma_fence_free(struct dma_fence *fence);
....@@ -273,7 +293,7 @@
273293 }
274294 
275295 /**
276
- * dma_fence_get_rcu - get a fence from a reservation_object_list with
296
+ * dma_fence_get_rcu - get a fence from a dma_resv_list with
277297  *                     rcu read lock
278298  * @fence: fence to increase refcount of
279299  *
....@@ -297,7 +317,7 @@
297317  * so long as the caller is using RCU on the pointer to the fence.
298318  *
299319  * An alternative mechanism is to employ a seqlock to protect a bunch of
300
- * fences, such as used by struct reservation_object. When using a seqlock,
320
+ * fences, such as used by struct dma_resv. When using a seqlock,
301321  * the seqlock must be taken before and checked after a reference to the
302322  * fence is acquired (as shown here).
303323  *
....@@ -337,8 +357,24 @@
337357 	} while (1);
338358 }
339359 
360
+#ifdef CONFIG_LOCKDEP
361
+bool dma_fence_begin_signalling(void);
362
+void dma_fence_end_signalling(bool cookie);
363
+void __dma_fence_might_wait(void);
364
+#else
365
+static inline bool dma_fence_begin_signalling(void)
366
+{
367
+	return true;
368
+}
369
+static inline void dma_fence_end_signalling(bool cookie) {}
370
+static inline void __dma_fence_might_wait(void) {}
371
+#endif
372
+
340373 int dma_fence_signal(struct dma_fence *fence);
341374 int dma_fence_signal_locked(struct dma_fence *fence);
375
+int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
376
+int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
377
+				      ktime_t timestamp);
342378 signed long dma_fence_default_wait(struct dma_fence *fence,
343379 				   bool intr, signed long timeout);
344380 int dma_fence_add_callback(struct dma_fence *fence,
....@@ -410,13 +446,22 @@
410446  * __dma_fence_is_later - return if f1 is chronologically later than f2
411447  * @f1: the first fence's seqno
412448  * @f2: the second fence's seqno from the same context
449
+ * @ops: dma_fence_ops associated with the seqno
413450  *
414451  * Returns true if f1 is chronologically later than f2. Both fences must be
415452  * from the same context, since a seqno is not common across contexts.
416453  */
417
-static inline bool __dma_fence_is_later(u32 f1, u32 f2)
454
+static inline bool __dma_fence_is_later(u64 f1, u64 f2,
455
+					const struct dma_fence_ops *ops)
418456 {
419
-	return (int)(f1 - f2) > 0;
457
+	/* This is for backward compatibility with drivers which can only handle
458
+	 * 32bit sequence numbers. Use a 64bit compare when the driver says to
459
+	 * do so.
460
+	 */
461
+	if (ops->use_64bit_seqno)
462
+		return f1 > f2;
463
+
464
+	return (int)(lower_32_bits(f1) - lower_32_bits(f2)) > 0;
420465 }
421466 
422467 /**
....@@ -433,7 +478,7 @@
433478 	if (WARN_ON(f1->context != f2->context))
434479 		return false;
435480 
436
-	return __dma_fence_is_later(f1->seqno, f2->seqno);
481
+	return __dma_fence_is_later(f1->seqno, f2->seqno, f1->ops);
437482 }
438483 
439484 /**
....@@ -541,27 +586,28 @@
541586 	return ret < 0 ? ret : 0;
542587 }
543588 
589
+struct dma_fence *dma_fence_get_stub(void);
544590 u64 dma_fence_context_alloc(unsigned num);
545591 
546592 #define DMA_FENCE_TRACE(f, fmt, args...) \
547593 	do {								\
548594 		struct dma_fence *__ff = (f);				\
549595 		if (IS_ENABLED(CONFIG_DMA_FENCE_TRACE))			\
550
-			pr_info("f %llu#%u: " fmt,			\
596
+			pr_info("f %llu#%llu: " fmt,			\
551597 				__ff->context, __ff->seqno, ##args);	\
552598 	} while (0)
553599 
554600 #define DMA_FENCE_WARN(f, fmt, args...) \
555601 	do {								\
556602 		struct dma_fence *__ff = (f);				\
557
-		pr_warn("f %llu#%u: " fmt, __ff->context, __ff->seqno,	\
603
+		pr_warn("f %llu#%llu: " fmt, __ff->context, __ff->seqno,\
558604 			 ##args);					\
559605 	} while (0)
560606 
561607 #define DMA_FENCE_ERR(f, fmt, args...) \
562608 	do {								\
563609 		struct dma_fence *__ff = (f);				\
564
-		pr_err("f %llu#%u: " fmt, __ff->context, __ff->seqno,	\
610
+		pr_err("f %llu#%llu: " fmt, __ff->context, __ff->seqno,	\
565611 			##args);					\
566612 	} while (0)
567613