drm/ttm: add VADDR_FLAG_UPDATED_COUNT to correctly update dma_page global count

add this for correctly updating global mem count in ttm_mem_zone.
before that when ttm_mem_global_alloc_page fails, we would update all
dma_page's global mem count in ttm_dma->pages_list. but actually here
we should not update for the last dma_page.

v2: only the update of last dma_page is not right
v3: use lower bits of dma_page vaddr
Signed-off-by: Roger He <Hongbo.He@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_page_alloc_dma.c

@@ -61,6 +61,7 @@
 #define SMALL_ALLOCATION		4
 #define FREE_ALL_PAGES			(~0U)
 #define VADDR_FLAG_HUGE_POOL		1UL
+#define VADDR_FLAG_UPDATED_COUNT	2UL
 
 enum pool_type {
 	IS_UNDEFINED	= 0,
@@ -874,18 +875,18 @@ static int ttm_dma_page_pool_fill_locked(struct dma_pool *pool,
 }
 
 /*
- * @return count of pages still required to fulfill the request.
  * The populate list is actually a stack (not that is matters as TTM
  * allocates one page at a time.
+ * return dma_page pointer if success, otherwise NULL.
  */
-static int ttm_dma_pool_get_pages(struct dma_pool *pool,
+static struct dma_page *ttm_dma_pool_get_pages(struct dma_pool *pool,
 				  struct ttm_dma_tt *ttm_dma,
 				  unsigned index)
 {
-	struct dma_page *d_page;
+	struct dma_page *d_page = NULL;
 	struct ttm_tt *ttm = &ttm_dma->ttm;
 	unsigned long irq_flags;
-	int count, r = -ENOMEM;
+	int count;
 
 	spin_lock_irqsave(&pool->lock, irq_flags);
 	count = ttm_dma_page_pool_fill_locked(pool, &irq_flags);
@@ -894,12 +895,11 @@ static int ttm_dma_pool_get_pages(struct dma_pool *pool,
 		ttm->pages[index] = d_page->p;
 		ttm_dma->dma_address[index] = d_page->dma;
 		list_move_tail(&d_page->page_list, &ttm_dma->pages_list);
-		r = 0;
 		pool->npages_in_use += 1;
 		pool->npages_free -= 1;
 	}
 	spin_unlock_irqrestore(&pool->lock, irq_flags);
-	return r;
+	return d_page;
 }
 
 static gfp_t ttm_dma_pool_gfp_flags(struct ttm_dma_tt *ttm_dma, bool huge)
@@ -934,6 +934,7 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
 	struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
 	unsigned long num_pages = ttm->num_pages;
 	struct dma_pool *pool;
+	struct dma_page *d_page;
 	enum pool_type type;
 	unsigned i;
 	int ret;
@@ -962,8 +963,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
 	while (num_pages >= HPAGE_PMD_NR) {
 		unsigned j;
 
-		ret = ttm_dma_pool_get_pages(pool, ttm_dma, i);
-		if (ret != 0)
+		d_page = ttm_dma_pool_get_pages(pool, ttm_dma, i);
+		if (!d_page)
 			break;
 
 		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
@@ -973,6 +974,7 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
 			return -ENOMEM;
 		}
 
+		d_page->vaddr |= VADDR_FLAG_UPDATED_COUNT;
 		for (j = i + 1; j < (i + HPAGE_PMD_NR); ++j) {
 			ttm->pages[j] = ttm->pages[j - 1] + 1;
 			ttm_dma->dma_address[j] = ttm_dma->dma_address[j - 1] +
@@ -996,8 +998,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
 	}
 
 	while (num_pages) {
-		ret = ttm_dma_pool_get_pages(pool, ttm_dma, i);
-		if (ret != 0) {
+		d_page = ttm_dma_pool_get_pages(pool, ttm_dma, i);
+		if (!d_page) {
 			ttm_dma_unpopulate(ttm_dma, dev);
 			return -ENOMEM;
 		}
@@ -1009,6 +1011,7 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
 			return -ENOMEM;
 		}
 
+		d_page->vaddr |= VADDR_FLAG_UPDATED_COUNT;
 		++i;
 		--num_pages;
 	}
@@ -1049,8 +1052,11 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
 				continue;
 
 			count++;
+			if (d_page->vaddr & VADDR_FLAG_UPDATED_COUNT) {
 				ttm_mem_global_free_page(ttm->glob->mem_glob,
 							 d_page->p, pool->size);
+				d_page->vaddr &= ~VADDR_FLAG_UPDATED_COUNT;
+			}
 			ttm_dma_page_put(pool, d_page);
 		}
 
@@ -1070,9 +1076,19 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
 
 	/* make sure pages array match list and count number of pages */
 	count = 0;
-	list_for_each_entry(d_page, &ttm_dma->pages_list, page_list) {
+	list_for_each_entry_safe(d_page, next, &ttm_dma->pages_list,
+				 page_list) {
 		ttm->pages[count] = d_page->p;
 		count++;
+
+		if (d_page->vaddr & VADDR_FLAG_UPDATED_COUNT) {
+			ttm_mem_global_free_page(ttm->glob->mem_glob,
+						 d_page->p, pool->size);
+			d_page->vaddr &= ~VADDR_FLAG_UPDATED_COUNT;
+		}
+
+		if (is_cached)
+			ttm_dma_page_put(pool, d_page);
 	}
 
 	spin_lock_irqsave(&pool->lock, irq_flags);
@@ -1092,19 +1108,6 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
 	}
 	spin_unlock_irqrestore(&pool->lock, irq_flags);
 
-	if (is_cached) {
-		list_for_each_entry_safe(d_page, next, &ttm_dma->pages_list, page_list) {
-			ttm_mem_global_free_page(ttm->glob->mem_glob,
-						 d_page->p, pool->size);
-			ttm_dma_page_put(pool, d_page);
-		}
-	} else {
-		for (i = 0; i < count; i++) {
-			ttm_mem_global_free_page(ttm->glob->mem_glob,
-						 ttm->pages[i], pool->size);
-		}
-	}
-
 	INIT_LIST_HEAD(&ttm_dma->pages_list);
 	for (i = 0; i < ttm->num_pages; i++) {
 		ttm->pages[i] = NULL;