[PATCH v2] dmaengine: dmatest: honor alignment restriction for buffers

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Existing implementation does not honor the alignment restrictions imposed
by the DMA engines. Allocate buffers with built in slack for honoring
alignment restrictions. Creating new arrays to hold the aligned pointers
and use those pointers for operations.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 drivers/dma/dmatest.c |   66 ++++++++++++++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 20 deletions(-)

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 3b358c4..451f899 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -164,7 +164,9 @@ struct dmatest_thread {
 	struct task_struct	*task;
 	struct dma_chan		*chan;
 	u8			**srcs;
+	u8			**usrcs;
 	u8			**dsts;
+	u8			**udsts;
 	enum dma_transaction_type type;
 	bool			done;
 };
@@ -431,6 +433,7 @@ static int dmatest_func(void *data)
 	ktime_t			comparetime = ktime_set(0, 0);
 	s64			runtime = 0;
 	unsigned long long	total_len = 0;
+	u8			align = 0;
 
 	set_freezable();
 
@@ -441,18 +444,22 @@ static int dmatest_func(void *data)
 	params = &info->params;
 	chan = thread->chan;
 	dev = chan->device;
-	if (thread->type == DMA_MEMCPY)
+	if (thread->type == DMA_MEMCPY) {
+		align = dev->copy_align;
 		src_cnt = dst_cnt = 1;
-	else if (thread->type == DMA_SG)
+	} else if (thread->type == DMA_SG) {
+		align = dev->copy_align;
 		src_cnt = dst_cnt = sg_buffers;
-	else if (thread->type == DMA_XOR) {
+	} else if (thread->type == DMA_XOR) {
 		/* force odd to ensure dst = src */
 		src_cnt = min_odd(params->xor_sources | 1, dev->max_xor);
 		dst_cnt = 1;
+		align = dev->xor_align;
 	} else if (thread->type == DMA_PQ) {
 		/* force odd to ensure dst = src */
 		src_cnt = min_odd(params->pq_sources | 1, dma_maxpq(dev, 0));
 		dst_cnt = 2;
+		align = dev->pq_align;
 
 		pq_coefs = kmalloc(params->pq_sources + 1, GFP_KERNEL);
 		if (!pq_coefs)
@@ -466,20 +473,44 @@ static int dmatest_func(void *data)
 	thread->srcs = kcalloc(src_cnt + 1, sizeof(u8 *), GFP_KERNEL);
 	if (!thread->srcs)
 		goto err_srcs;
+
+	thread->usrcs = kcalloc(src_cnt + 1, sizeof(u8 *), GFP_KERNEL);
+	if (!thread->usrcs)
+		goto err_usrcs;
+
 	for (i = 0; i < src_cnt; i++) {
-		thread->srcs[i] = kmalloc(params->buf_size, GFP_KERNEL);
-		if (!thread->srcs[i])
+		thread->usrcs[i] = kmalloc(params->buf_size + align,
+					   GFP_KERNEL);
+		if (!thread->usrcs[i])
 			goto err_srcbuf;
+
+		/* align srcs to alignment restriction */
+		if (align)
+			thread->srcs[i] = PTR_ALIGN(thread->usrcs[i], align);
+		else
+			thread->srcs[i] = thread->usrcs[i];
 	}
 	thread->srcs[i] = NULL;
 
 	thread->dsts = kcalloc(dst_cnt + 1, sizeof(u8 *), GFP_KERNEL);
 	if (!thread->dsts)
 		goto err_dsts;
+
+	thread->udsts = kcalloc(dst_cnt + 1, sizeof(u8 *), GFP_KERNEL);
+	if (!thread->udsts)
+		goto err_udsts;
+
 	for (i = 0; i < dst_cnt; i++) {
-		thread->dsts[i] = kmalloc(params->buf_size, GFP_KERNEL);
-		if (!thread->dsts[i])
+		thread->udsts[i] = kmalloc(params->buf_size + align,
+					   GFP_KERNEL);
+		if (!thread->udsts[i])
 			goto err_dstbuf;
+
+		/* align dsts to alignment restriction */
+		if (align)
+			thread->dsts[i] = PTR_ALIGN(thread->udsts[i], align);
+		else
+			thread->dsts[i] = thread->udsts[i];
 	}
 	thread->dsts[i] = NULL;
 
@@ -498,20 +529,11 @@ static int dmatest_func(void *data)
 		dma_addr_t srcs[src_cnt];
 		dma_addr_t *dsts;
 		unsigned int src_off, dst_off, len;
-		u8 align = 0;
 		struct scatterlist tx_sg[src_cnt];
 		struct scatterlist rx_sg[src_cnt];
 
 		total_tests++;
 
-		/* honor alignment restrictions */
-		if (thread->type == DMA_MEMCPY || thread->type == DMA_SG)
-			align = dev->copy_align;
-		else if (thread->type == DMA_XOR)
-			align = dev->xor_align;
-		else if (thread->type == DMA_PQ)
-			align = dev->pq_align;
-
 		if (1 << align > params->buf_size) {
 			pr_err("%u-byte buffer too small for %d-byte alignment\n",
 			       params->buf_size, 1 << align);
@@ -729,13 +751,17 @@ static int dmatest_func(void *data)
 
 	ret = 0;
 err_dstbuf:
-	for (i = 0; thread->dsts[i]; i++)
-		kfree(thread->dsts[i]);
+	for (i = 0; thread->udsts[i]; i++)
+		kfree(thread->udsts[i]);
+	kfree(thread->udsts);
+err_udsts:
 	kfree(thread->dsts);
 err_dsts:
 err_srcbuf:
-	for (i = 0; thread->srcs[i]; i++)
-		kfree(thread->srcs[i]);
+	for (i = 0; thread->usrcs[i]; i++)
+		kfree(thread->usrcs[i]);
+	kfree(thread->usrcs);
+err_usrcs:
 	kfree(thread->srcs);
 err_srcs:
 	kfree(pq_coefs);

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