dmanegine: ioat/dca: Use struct_size() helper

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct ioat_dca_priv {
	...
        struct ioat_dca_slot     req_slots[0];
};

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(*ioatdca) + (sizeof(struct ioat_dca_slot) * slots)

with:

struct_size(ioatdca, req_slots, slots)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20190828184015.GA4273@embeddedor
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/ioat/dca.c b/drivers/dma/ioat/dca.c
index 70fd845..be61c32 100644 (file)
--- a/drivers/dma/ioat/dca.c
+++ b/drivers/dma/ioat/dca.c
@@ -286,8 +286,7 @@ struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
                return NULL;
 
        dca = alloc_dca_provider(&ioat_dca_ops,
-                                sizeof(*ioatdca)
-                                     + (sizeof(struct ioat_dca_slot) * slots));
+                                struct_size(ioatdca, req_slots, slots));
        if (!dca)
                return NULL;