iommu/mtk_iommu: Use devm_kcalloc() instead of devm_kzalloc()

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because MTK_PROTECT_PA_ALIGN
is defined as a literal value of 256 or 128.

For the "mtk_iommu.c" file: 256
For the "mtk_iommu_v1.c" file: 128

However, using devm_kcalloc() is more appropriate [2] and improves
readability. This patch has no effect on runtime behavior.

Link: KSPP#162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [2]
Signed-off-by: Erick Archer <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Matthias Brugger <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: Erick Archer

drivers/iommu/mtk_iommu.c

@@ -1264,7 +1264,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 	data->plat_data = of_device_get_match_data(dev);
 
 	/* Protect memory. HW will access here while translation fault.*/
-	protect = devm_kzalloc(dev, MTK_PROTECT_PA_ALIGN * 2, GFP_KERNEL);
+	protect = devm_kcalloc(dev, 2, MTK_PROTECT_PA_ALIGN, GFP_KERNEL);
 	if (!protect)
 		return -ENOMEM;
 	data->protect_base = ALIGN(virt_to_phys(protect), MTK_PROTECT_PA_ALIGN);

drivers/iommu/mtk_iommu_v1.c

@@ -621,8 +621,8 @@ static int mtk_iommu_v1_probe(struct platform_device *pdev)
 	data->dev = dev;
 
 	/* Protect memory. HW will access here while translation fault.*/
-	protect = devm_kzalloc(dev, MTK_PROTECT_PA_ALIGN * 2,
-			GFP_KERNEL | GFP_DMA);
+	protect = devm_kcalloc(dev, 2, MTK_PROTECT_PA_ALIGN,
+			       GFP_KERNEL | GFP_DMA);
 	if (!protect)
 		return -ENOMEM;
 	data->protect_base = ALIGN(virt_to_phys(protect), MTK_PROTECT_PA_ALIGN);