[PATCH v7 12/24] dmaengine: ste_dma40: Fix LCLA allocation order

[Linus Walleij <linusw@kernel.org>]

d40_lcla_allocate() calculates the number of pages needed for LCLA, but
passes that raw page count as the allocation order to __get_free_pages().
The same value is later passed to free_pages().

Store the allocation order with get_order() instead, and use a separate
byte size for allocation diagnostics, fallback kmalloc() sizing and DMA
mapping.

Fixes: 508849ade23c ("DMAENGINE: ste_dma40: allocate LCLA dynamically")
Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/dmaengine/20260819225114.AE1511F000E9@smtp.kernel.org/
Assisted-by: LLM
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/dma/ste_dma40.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index f72d91c8d0fa..58bc08c2ed0f 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -426,8 +426,8 @@ struct d40_desc {
  * @dma_addr: DMA address, if mapped
  * @base_unaligned: The original kmalloc pointer, if kmalloc is used.
  * This pointer is only there for clean-up on error.
- * @pages: The number of pages needed for all physical channels.
- * Only used later for clean-up on error
+ * @alloc_order: Order used for the LCLA page allocation.
+ * Only used later for clean-up on error.
  * @lock: Lock to protect the content in this struct.
  * @alloc_map: big map over which LCLA entry is own by which job.
  */
@@ -435,7 +435,7 @@ struct d40_lcla_pool {
 	void		*base;
 	dma_addr_t	dma_addr;
 	void		*base_unaligned;
-	int		 pages;
+	unsigned int	 alloc_order;
 	spinlock_t	 lock;
 	struct d40_desc	**alloc_map;
 };
@@ -3603,6 +3603,7 @@ static void __init d40_hw_init(struct d40_base *base)
 static int __init d40_lcla_allocate(struct d40_base *base)
 {
 	struct d40_lcla_pool *pool = &base->lcla_pool;
+	size_t lcla_size = SZ_1K * base->num_phy_chans;
 	unsigned long *page_list;
 	int i, j;
 	int ret;
@@ -3618,20 +3619,20 @@ static int __init d40_lcla_allocate(struct d40_base *base)
 	if (!page_list)
 		return -ENOMEM;
 
-	/* Calculating how many pages that are required */
-	base->lcla_pool.pages = SZ_1K * base->num_phy_chans / PAGE_SIZE;
+	base->lcla_pool.alloc_order = get_order(lcla_size);
 
 	for (i = 0; i < MAX_LCLA_ALLOC_ATTEMPTS; i++) {
 		page_list[i] = __get_free_pages(GFP_KERNEL,
-						base->lcla_pool.pages);
+						base->lcla_pool.alloc_order);
 		if (!page_list[i]) {
 
-			d40_err(base->dev, "Failed to allocate %d pages.\n",
-				base->lcla_pool.pages);
+			d40_err(base->dev, "Failed to allocate %zu bytes.\n",
+				lcla_size);
 			ret = -ENOMEM;
 
 			for (j = 0; j < i; j++)
-				free_pages(page_list[j], base->lcla_pool.pages);
+				free_pages(page_list[j],
+					   base->lcla_pool.alloc_order);
 			goto free_page_list;
 		}
 
@@ -3641,7 +3642,7 @@ static int __init d40_lcla_allocate(struct d40_base *base)
 	}
 
 	for (j = 0; j < i; j++)
-		free_pages(page_list[j], base->lcla_pool.pages);
+		free_pages(page_list[j], base->lcla_pool.alloc_order);
 
 	if (i < MAX_LCLA_ALLOC_ATTEMPTS) {
 		base->lcla_pool.base = (void *)page_list[i];
@@ -3651,10 +3652,9 @@ static int __init d40_lcla_allocate(struct d40_base *base)
 		 * alignment, try with allocating a big buffer.
 		 */
 		dev_warn(base->dev,
-			 "[%s] Failed to get %d pages @ 18 bit align.\n",
-			 __func__, base->lcla_pool.pages);
-		base->lcla_pool.base_unaligned = kmalloc(SZ_1K *
-							 base->num_phy_chans +
+			 "[%s] Failed to get %zu bytes @ 18 bit align.\n",
+			 __func__, lcla_size);
+		base->lcla_pool.base_unaligned = kmalloc(lcla_size +
 							 LCLA_ALIGNMENT,
 							 GFP_KERNEL);
 		if (!base->lcla_pool.base_unaligned) {
@@ -3666,8 +3666,7 @@ static int __init d40_lcla_allocate(struct d40_base *base)
 						 LCLA_ALIGNMENT);
 	}
 
-	pool->dma_addr = dma_map_single(base->dev, pool->base,
-					SZ_1K * base->num_phy_chans,
+	pool->dma_addr = dma_map_single(base->dev, pool->base, lcla_size,
 					DMA_TO_DEVICE);
 	if (dma_mapping_error(base->dev, pool->dma_addr)) {
 		pool->dma_addr = 0;
@@ -3909,7 +3908,7 @@ static int __init d40_probe(struct platform_device *pdev)
 
 	if (!base->lcla_pool.base_unaligned && base->lcla_pool.base)
 		free_pages((unsigned long)base->lcla_pool.base,
-			   base->lcla_pool.pages);
+			   base->lcla_pool.alloc_order);
 
 	kfree(base->lcla_pool.base_unaligned);
 

-- 
2.55.0