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* [PATCH] dmaengine: idma64: use kzalloc_flex
@ 2026-03-17  0:37 Rosen Penev
  2026-03-20  7:51 ` kernel test robot
  0 siblings, 1 reply; 2+ messages in thread
From: Rosen Penev @ 2026-03-17  0:37 UTC (permalink / raw)
  To: dmaengine
  Cc: Vinod Koul, Frank Li, Kees Cook, Gustavo A. R. Silva, open list,
	open list:KERNEL HARDENING (not covered by other areas):Keyword:b__counted_by(_le|_be)?b

Simplifies allocations by using a flexible array member in this struct.

Remove idma64_alloc_desc. It now offers no readability advantages in
this single usage.

Add __counted_by to get extra runtime analysis.

Apply the exact same treatment to struct idma64_dma and devm_kzalloc.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/dma/idma64.c | 30 ++++--------------------------
 drivers/dma/idma64.h |  4 ++--
 2 files changed, 6 insertions(+), 28 deletions(-)

diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
index 5fcd1befc92d..cf0399251ea9 100644
--- a/drivers/dma/idma64.c
+++ b/drivers/dma/idma64.c
@@ -192,23 +192,6 @@ static irqreturn_t idma64_irq(int irq, void *dev)
 
 /* ---------------------------------------------------------------------- */
 
-static struct idma64_desc *idma64_alloc_desc(unsigned int ndesc)
-{
-	struct idma64_desc *desc;
-
-	desc = kzalloc_obj(*desc, GFP_NOWAIT);
-	if (!desc)
-		return NULL;
-
-	desc->hw = kzalloc_objs(*desc->hw, ndesc, GFP_NOWAIT);
-	if (!desc->hw) {
-		kfree(desc);
-		return NULL;
-	}
-
-	return desc;
-}
-
 static void idma64_desc_free(struct idma64_chan *idma64c,
 		struct idma64_desc *desc)
 {
@@ -223,7 +206,6 @@ static void idma64_desc_free(struct idma64_chan *idma64c,
 		} while (i);
 	}
 
-	kfree(desc->hw);
 	kfree(desc);
 }
 
@@ -307,10 +289,12 @@ static struct dma_async_tx_descriptor *idma64_prep_slave_sg(
 	struct scatterlist *sg;
 	unsigned int i;
 
-	desc = idma64_alloc_desc(sg_len);
+	desc = kzalloc_flex(*desc, hw, sg_len);
 	if (!desc)
 		return NULL;
 
+	desc->ndesc = sg_len;
+
 	for_each_sg(sgl, sg, sg_len, i) {
 		struct idma64_hw_desc *hw = &desc->hw[i];
 
@@ -326,7 +310,6 @@ static struct dma_async_tx_descriptor *idma64_prep_slave_sg(
 		hw->len = sg_dma_len(sg);
 	}
 
-	desc->ndesc = sg_len;
 	desc->direction = direction;
 	desc->status = DMA_IN_PROGRESS;
 
@@ -541,18 +524,13 @@ static int idma64_probe(struct idma64_chip *chip)
 	unsigned short i;
 	int ret;
 
-	idma64 = devm_kzalloc(chip->dev, sizeof(*idma64), GFP_KERNEL);
+	idma64 = devm_kzalloc(chip->dev, struct_size(idma64, chan, nr_chan), GFP_KERNEL);
 	if (!idma64)
 		return -ENOMEM;
 
 	idma64->regs = chip->regs;
 	chip->idma64 = idma64;
 
-	idma64->chan = devm_kcalloc(chip->dev, nr_chan, sizeof(*idma64->chan),
-				    GFP_KERNEL);
-	if (!idma64->chan)
-		return -ENOMEM;
-
 	idma64->all_chan_mask = (1 << nr_chan) - 1;
 
 	/* Turn off iDMA controller */
diff --git a/drivers/dma/idma64.h b/drivers/dma/idma64.h
index d013b54356aa..1a67dbb24db5 100644
--- a/drivers/dma/idma64.h
+++ b/drivers/dma/idma64.h
@@ -113,10 +113,10 @@ struct idma64_hw_desc {
 struct idma64_desc {
 	struct virt_dma_desc vdesc;
 	enum dma_transfer_direction direction;
-	struct idma64_hw_desc *hw;
 	unsigned int ndesc;
 	size_t length;
 	enum dma_status status;
+	struct idma64_hw_desc hw[] __counted_by(ndesc);
 };
 
 static inline struct idma64_desc *to_idma64_desc(struct virt_dma_desc *vdesc)
@@ -187,7 +187,7 @@ struct idma64 {
 
 	/* channels */
 	unsigned short all_chan_mask;
-	struct idma64_chan *chan;
+	struct idma64_chan chan[];
 };
 
 static inline struct idma64 *to_idma64(struct dma_device *ddev)
-- 
2.53.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-03-20  7:51 UTC | newest]

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2026-03-17  0:37 [PATCH] dmaengine: idma64: use kzalloc_flex Rosen Penev
2026-03-20  7:51 ` kernel test robot

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