dma-buf: make fence sequence numbers 64 bit v2

For a lot of use cases we need 64bit sequence numbers. Currently drivers
overload the dma_fence structure to store the additional bits.

Stop doing that and make the sequence number in the dma_fence always
64bit.

For compatibility with hardware which can do only 32bit sequences the
comparisons in __dma_fence_is_later only takes the lower 32bits as significant
when the upper 32bits are all zero.

v2: change the logic in __dma_fence_is_later
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/266927/

drivers/dma-buf/dma-fence.c

@@ -649,7 +649,7 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
  */
 void
 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
-	       spinlock_t *lock, u64 context, unsigned seqno)
+	       spinlock_t *lock, u64 context, u64 seqno)
 {
 	BUG_ON(!lock);
 	BUG_ON(!ops || !ops->get_driver_name || !ops->get_timeline_name);

drivers/dma-buf/sw_sync.c

@@ -172,7 +172,7 @@ static bool timeline_fence_enable_signaling(struct dma_fence *fence)
 static void timeline_fence_value_str(struct dma_fence *fence,
 				    char *str, int size)
 {
-	snprintf(str, size, "%d", fence->seqno);
+	snprintf(str, size, "%lld", fence->seqno);
 }
 
 static void timeline_fence_timeline_value_str(struct dma_fence *fence,

drivers/dma-buf/sync_file.c

@@ -144,7 +144,7 @@ char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
 	} else {
 		struct dma_fence *fence = sync_file->fence;
 
-		snprintf(buf, len, "%s-%s%llu-%d",
+		snprintf(buf, len, "%s-%s%llu-%lld",
 			 fence->ops->get_driver_name(fence),
 			 fence->ops->get_timeline_name(fence),
 			 fence->context,
@@ -258,7 +258,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 
 			i_b++;
 		} else {
-			if (pt_a->seqno - pt_b->seqno <= INT_MAX)
+			if (__dma_fence_is_later(pt_a->seqno, pt_b->seqno))
 				add_fence(fences, &i, pt_a);
 			else
 				add_fence(fences, &i, pt_b);

drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c

@@ -388,7 +388,7 @@ void amdgpu_sa_bo_dump_debug_info(struct amdgpu_sa_manager *sa_manager,
 			   soffset, eoffset, eoffset - soffset);
 
 		if (i->fence)
-			seq_printf(m, " protected by 0x%08x on context %llu",
+			seq_printf(m, " protected by 0x%016llx on context %llu",
 				   i->fence->seqno, i->fence->context);
 
 		seq_printf(m, "\n");

drivers/gpu/drm/i915/i915_sw_fence.c

@@ -393,7 +393,7 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
 	if (!fence)
 		return;
 
-	pr_notice("Asynchronous wait on fence %s:%s:%x timed out (hint:%pS)\n",
+	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%pS)\n",
 		  cb->dma->ops->get_driver_name(cb->dma),
 		  cb->dma->ops->get_timeline_name(cb->dma),
 		  cb->dma->seqno,

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -1239,7 +1239,7 @@ static void print_request(struct drm_printer *m,
 
 	x = print_sched_attr(rq->i915, &rq->sched.attr, buf, x, sizeof(buf));
 
-	drm_printf(m, "%s%x%s [%llx:%x]%s @ %dms: %s\n",
+	drm_printf(m, "%s%x%s [%llx:%llx]%s @ %dms: %s\n",
 		   prefix,
 		   rq->global_seqno,
 		   i915_request_completed(rq) ? "!" : "",

drivers/gpu/drm/vgem/vgem_fence.c

@@ -53,13 +53,13 @@ static void vgem_fence_release(struct dma_fence *base)
 
 static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
 {
-	snprintf(str, size, "%u", fence->seqno);
+	snprintf(str, size, "%llu", fence->seqno);
 }
 
 static void vgem_fence_timeline_value_str(struct dma_fence *fence, char *str,
 					  int size)
 {
-	snprintf(str, size, "%u",
+	snprintf(str, size, "%llu",
 		 dma_fence_is_signaled(fence) ? fence->seqno : 0);
 }
 

include/linux/dma-fence.h

@@ -77,7 +77,7 @@ struct dma_fence {
 	struct list_head cb_list;
 	spinlock_t *lock;
 	u64 context;
-	unsigned seqno;
+	u64 seqno;
 	unsigned long flags;
 	ktime_t timestamp;
 	int error;
@@ -244,7 +244,7 @@ struct dma_fence_ops {
 };
 
 void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
-		    spinlock_t *lock, u64 context, unsigned seqno);
+		    spinlock_t *lock, u64 context, u64 seqno);
 
 void dma_fence_release(struct kref *kref);
 void dma_fence_free(struct dma_fence *fence);
@@ -414,9 +414,17 @@ dma_fence_is_signaled(struct dma_fence *fence)
  * Returns true if f1 is chronologically later than f2. Both fences must be
  * from the same context, since a seqno is not common across contexts.
  */
-static inline bool __dma_fence_is_later(u32 f1, u32 f2)
+static inline bool __dma_fence_is_later(u64 f1, u64 f2)
 {
-	return (int)(f1 - f2) > 0;
+	/* This is for backward compatibility with drivers which can only handle
+	 * 32bit sequence numbers. Use a 64bit compare when any of the higher
+	 * bits are none zero, otherwise use a 32bit compare with wrap around
+	 * handling.
+	 */
+	if (upper_32_bits(f1) || upper_32_bits(f2))
+		return f1 > f2;
+
+	return (int)(lower_32_bits(f1) - lower_32_bits(f2)) > 0;
 }
 
 /**
@@ -548,21 +556,21 @@ u64 dma_fence_context_alloc(unsigned num);
 	do {								\
 		struct dma_fence *__ff = (f);				\
 		if (IS_ENABLED(CONFIG_DMA_FENCE_TRACE))			\
-			pr_info("f %llu#%u: " fmt,			\
+			pr_info("f %llu#%llu: " fmt,			\
 				__ff->context, __ff->seqno, ##args);	\
 	} while (0)
 
 #define DMA_FENCE_WARN(f, fmt, args...) \
 	do {								\
 		struct dma_fence *__ff = (f);				\
-		pr_warn("f %llu#%u: " fmt, __ff->context, __ff->seqno,	\
+		pr_warn("f %llu#%llu: " fmt, __ff->context, __ff->seqno,\
 			 ##args);					\
 	} while (0)
 
 #define DMA_FENCE_ERR(f, fmt, args...) \
 	do {								\
 		struct dma_fence *__ff = (f);				\
-		pr_err("f %llu#%u: " fmt, __ff->context, __ff->seqno,	\
+		pr_err("f %llu#%llu: " fmt, __ff->context, __ff->seqno,	\
 			##args);					\
 	} while (0)