[PATCH wireless-next] wifi: b43legacy: Use flexible array for DMA metadata

[PATCH wireless-next] wifi: b43legacy: Use flexible array for DMA metadata

[Rosen Penev]

Store the per-descriptor metadata in the DMA ring allocation instead of
allocating it separately.

This ties the metadata lifetime directly to the ring, removes a separate
allocation failure path, and keeps the descriptor count available for
__counted_by() bounds checking.

Assisted-by: Codex:GPT-5.5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/net/wireless/broadcom/b43legacy/dma.c | 24 ++++++++-----------
 drivers/net/wireless/broadcom/b43legacy/dma.h |  4 ++--
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
index a9557356c9ab..6c3d847242bb 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.c
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
@@ -610,25 +610,25 @@ struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev,
 	int nr_slots;
 	dma_addr_t dma_test;
 
-	ring = kzalloc_obj(*ring);
+	if (for_tx)
+		nr_slots = B43legacy_TXRING_SLOTS;
+	else
+		nr_slots = B43legacy_RXRING_SLOTS;
+
+	ring = kzalloc_flex(*ring, meta, nr_slots);
 	if (!ring)
 		goto out;
+
+	ring->nr_slots = nr_slots;
 	ring->type = type;
 	ring->dev = dev;
 
-	nr_slots = B43legacy_RXRING_SLOTS;
-	if (for_tx)
-		nr_slots = B43legacy_TXRING_SLOTS;
-
-	ring->meta = kzalloc_objs(struct b43legacy_dmadesc_meta, nr_slots);
-	if (!ring->meta)
-		goto err_kfree_ring;
 	if (for_tx) {
 		ring->txhdr_cache = kcalloc(nr_slots,
 					sizeof(struct b43legacy_txhdr_fw3),
 					GFP_KERNEL);
 		if (!ring->txhdr_cache)
-			goto err_kfree_meta;
+			goto err_kfree_ring;
 
 		/* test for ability to dma to txhdr_cache */
 		dma_test = dma_map_single(dev->dev->dma_dev, ring->txhdr_cache,
@@ -643,7 +643,7 @@ struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev,
 					sizeof(struct b43legacy_txhdr_fw3),
 					GFP_KERNEL | GFP_DMA);
 			if (!ring->txhdr_cache)
-				goto err_kfree_meta;
+				goto err_kfree_txhdr_cache;
 
 			dma_test = dma_map_single(dev->dev->dma_dev,
 					ring->txhdr_cache,
@@ -660,7 +660,6 @@ struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev,
 				 DMA_TO_DEVICE);
 	}
 
-	ring->nr_slots = nr_slots;
 	ring->mmio_base = b43legacy_dmacontroller_base(type, controller_index);
 	ring->index = controller_index;
 	if (for_tx) {
@@ -694,8 +693,6 @@ struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev,
 	free_ringmemory(ring);
 err_kfree_txhdr_cache:
 	kfree(ring->txhdr_cache);
-err_kfree_meta:
-	kfree(ring->meta);
 err_kfree_ring:
 	kfree(ring);
 	ring = NULL;
@@ -720,7 +717,6 @@ static void b43legacy_destroy_dmaring(struct b43legacy_dmaring *ring)
 	free_ringmemory(ring);
 
 	kfree(ring->txhdr_cache);
-	kfree(ring->meta);
 	kfree(ring);
 }
 
diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.h b/drivers/net/wireless/broadcom/b43legacy/dma.h
index b5c1a51db2a4..edd06225b64f 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.h
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.h
@@ -122,8 +122,6 @@ enum b43legacy_dmatype {
 struct b43legacy_dmaring {
 	/* Kernel virtual base address of the ring memory. */
 	void *descbase;
-	/* Meta data about all descriptors. */
-	struct b43legacy_dmadesc_meta *meta;
 	/* Cache of TX headers for each slot.
 	 * This is to avoid an allocation on each TX.
 	 * This is NULL for an RX ring.
@@ -161,6 +159,8 @@ struct b43legacy_dmaring {
 	/* Last time we injected a ring overflow. */
 	unsigned long last_injected_overflow;
 #endif /* CONFIG_B43LEGACY_DEBUG*/
+	/* Meta data about all descriptors. */
+	struct b43legacy_dmadesc_meta meta[] __counted_by(nr_slots);
 };
 
 
-- 
2.54.0