dmaengine: stm32-dma: Use struct_size() helper (402096cb) · Commits · 戴 / test

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 stm32_dma_desc { ... struct stm32_dma_sg_req sg_req[]; }; 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 function: static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs) { return kzalloc(sizeof(struct stm32_dma_desc) + sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT); } with: kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT) This code was detected with the help of Coccinelle. Signed-off-by:

Gustavo A. R. Silva <gustavo@embeddedor.com> Link: https://lore.kernel.org/r/20190830161423.GA3483@embeddedor Signed-off-by:

Vinod Koul <vkoul@kernel.org>

drivers/dma/stm32-dma.c

+3 −9

Original line number	Diff line number	Diff line
		@@ -243,12 +243,6 @@ static void stm32_dma_write(struct stm32_dma_device *dmadev, u32 reg, u32 val)
		writel_relaxed(val, dmadev->base + reg);
		}

		static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs)
		{
		return kzalloc(sizeof(struct stm32_dma_desc) +
		sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT);
		}

		static int stm32_dma_get_width(struct stm32_dma_chan *chan,
		enum dma_slave_buswidth width)
		{
		@@ -853,7 +847,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
		return NULL;
		}

		desc = stm32_dma_alloc_desc(sg_len);
		desc = kzalloc(struct_size(desc, sg_req, sg_len), GFP_NOWAIT);
		if (!desc)
		return NULL;

		@@ -954,7 +948,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(

		num_periods = buf_len / period_len;

		desc = stm32_dma_alloc_desc(num_periods);
		desc = kzalloc(struct_size(desc, sg_req, num_periods), GFP_NOWAIT);
		if (!desc)
		return NULL;

		@@ -989,7 +983,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
		int i;

		num_sgs = DIV_ROUND_UP(len, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
		desc = stm32_dma_alloc_desc(num_sgs);
		desc = kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT);
		if (!desc)
		return NULL;

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