Change desc_blocks to a flexible array member so the descriptor and
its block array are allocated together, removing one allocation and
its error handling.

Add __counted_by for extra runtime analysis, and set dblk_num right
after allocation which is already done by kzalloc_flex() for GCC >= 15.

Assisted-by: LLM
Signed-off-by: Rosen Penev <[email protected]>
---
 drivers/dma/xilinx/xdma.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 8d4a5d14e8db..16d202722245 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -81,7 +81,6 @@ struct xdma_chan {
  * @vdesc: Virtual DMA descriptor
  * @chan: DMA channel pointer
  * @dir: Transferring direction of the request
- * @desc_blocks: Hardware descriptor blocks
  * @dblk_num: Number of hardware descriptor blocks
  * @desc_num: Number of hardware descriptors
  * @completed_desc_num: Completed hardware descriptors
@@ -91,12 +90,12 @@ struct xdma_chan {
  * @period_size: Size of a period in bytes in cyclic transfers
  * @frames_left: Number of frames left in interleaved DMA transfer
  * @error: tx error flag
+ * @desc_blocks: Hardware descriptor blocks
  */
 struct xdma_desc {
        struct virt_dma_desc            vdesc;
        struct xdma_chan                *chan;
        enum dma_transfer_direction     dir;
-       struct xdma_desc_block          *desc_blocks;
        u32                             dblk_num;
        u32                             desc_num;
        u32                             completed_desc_num;
@@ -106,6 +105,7 @@ struct xdma_desc {
        u32                             period_size;
        u32                             frames_left;
        bool                            error;
+       struct xdma_desc_block          desc_blocks[] __counted_by(dblk_num);
 };
 
 #define XDMA_DEV_STATUS_REG_DMA                BIT(0)
@@ -255,7 +255,6 @@ static void xdma_free_desc(struct virt_dma_desc *vdesc)
                              sw_desc->desc_blocks[i].virt_addr,
                              sw_desc->desc_blocks[i].dma_addr);
        }
-       kfree(sw_desc->desc_blocks);
        kfree(sw_desc);
 }
 
@@ -276,26 +275,22 @@ xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num, 
bool cyclic)
        void *addr;
        int i, j;
 
-       sw_desc = kzalloc_obj(*sw_desc, GFP_NOWAIT);
+       dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
+       sw_desc = kzalloc_flex(*sw_desc, desc_blocks, dblk_num, GFP_NOWAIT);
        if (!sw_desc)
                return NULL;
 
+       sw_desc->dblk_num = dblk_num;
        sw_desc->chan = chan;
        sw_desc->desc_num = desc_num;
        sw_desc->cyclic = cyclic;
        sw_desc->error = false;
-       dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
-       sw_desc->desc_blocks = kzalloc_objs(*sw_desc->desc_blocks, dblk_num,
-                                           GFP_NOWAIT);
-       if (!sw_desc->desc_blocks)
-               goto failed;
 
        if (cyclic)
                control = XDMA_DESC_CONTROL_CYCLIC;
        else
                control = XDMA_DESC_CONTROL(1, 0);
 
-       sw_desc->dblk_num = dblk_num;
        for (i = 0; i < sw_desc->dblk_num; i++) {
                addr = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT, &dma_addr);
                if (!addr)
-- 
2.56.0


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