[net-next PATCH v5 3/7] net: ravb: Refactor RX ring refill

From: Paul Barker
Date: Tue Jun 04 2024 - 03:30:20 EST

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To reduce code duplication, we add a new RX ring refill function which
can handle both the initial RX ring population (which was split between
ravb_ring_init() and ravb_ring_format()) and the RX ring refill after
polling (in ravb_rx()).

Signed-off-by: Paul Barker <paul.barker.ct@xxxxxxxxxxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
---
Changes v4->v5:
* Re-wrapped to 80 cols, except where this would significantly impact
readability.
* Added Sergey's Reviewed-by tag.

Changes v3->v4:
* Avoided unnecessarily re-ordering code in ravb_ring_init() and
ravb_ring_format().

drivers/net/ethernet/renesas/ravb_main.c | 150 +++++++++--------------
1 file changed, 57 insertions(+), 93 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 472aa80002be..63d03929e3f5 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -317,35 +317,43 @@ static void ravb_ring_free(struct net_device *ndev, int q)
priv->tx_skb[q] = NULL;
}

-static void ravb_rx_ring_format(struct net_device *ndev, int q)
+static u32
+ravb_rx_ring_refill(struct net_device *ndev, int q, u32 count, gfp_t gfp_mask)
{
struct ravb_private *priv = netdev_priv(ndev);
+ const struct ravb_hw_info *info = priv->info;
struct ravb_rx_desc *rx_desc;
- unsigned int rx_ring_size;
dma_addr_t dma_addr;
- unsigned int i;
+ u32 i, entry;

- rx_ring_size = priv->info->rx_desc_size * priv->num_rx_ring[q];
- memset(priv->rx_ring[q].raw, 0, rx_ring_size);
- /* Build RX ring buffer */
- for (i = 0; i < priv->num_rx_ring[q]; i++) {
- /* RX descriptor */
- rx_desc = ravb_rx_get_desc(priv, q, i);
- rx_desc->ds_cc = cpu_to_le16(priv->info->rx_max_desc_use);
- dma_addr = dma_map_single(ndev->dev.parent, priv->rx_skb[q][i]->data,
- priv->info->rx_max_frame_size,
- DMA_FROM_DEVICE);
- /* We just set the data size to 0 for a failed mapping which
- * should prevent DMA from happening...
- */
- if (dma_mapping_error(ndev->dev.parent, dma_addr))
- rx_desc->ds_cc = cpu_to_le16(0);
- rx_desc->dptr = cpu_to_le32(dma_addr);
+ for (i = 0; i < count; i++) {
+ entry = (priv->dirty_rx[q] + i) % priv->num_rx_ring[q];
+ rx_desc = ravb_rx_get_desc(priv, q, entry);
+ rx_desc->ds_cc = cpu_to_le16(info->rx_max_desc_use);
+
+ if (!priv->rx_skb[q][entry]) {
+ priv->rx_skb[q][entry] = ravb_alloc_skb(ndev, info,
+ gfp_mask);
+ if (!priv->rx_skb[q][entry])
+ break;
+ dma_addr = dma_map_single(ndev->dev.parent,
+ priv->rx_skb[q][entry]->data,
+ priv->info->rx_max_frame_size,
+ DMA_FROM_DEVICE);
+ skb_checksum_none_assert(priv->rx_skb[q][entry]);
+ /* We just set the data size to 0 for a failed mapping
+ * which should prevent DMA from happening...
+ */
+ if (dma_mapping_error(ndev->dev.parent, dma_addr))
+ rx_desc->ds_cc = cpu_to_le16(0);
+ rx_desc->dptr = cpu_to_le32(dma_addr);
+ }
+ /* Descriptor type must be set after all the above writes */
+ dma_wmb();
rx_desc->die_dt = DT_FEMPTY;
}
- rx_desc = ravb_rx_get_desc(priv, q, i);
- rx_desc->dptr = cpu_to_le32((u32)priv->rx_desc_dma[q]);
- rx_desc->die_dt = DT_LINKFIX; /* type */
+
+ return i;
}

/* Format skb and descriptor buffer for Ethernet AVB */
@@ -353,6 +361,7 @@ static void ravb_ring_format(struct net_device *ndev, int q)
{
struct ravb_private *priv = netdev_priv(ndev);
unsigned int num_tx_desc = priv->num_tx_desc;
+ struct ravb_rx_desc *rx_desc;
struct ravb_tx_desc *tx_desc;
struct ravb_desc *desc;
unsigned int tx_ring_size = sizeof(*tx_desc) * priv->num_tx_ring[q] *
@@ -364,7 +373,13 @@ static void ravb_ring_format(struct net_device *ndev, int q)
priv->dirty_rx[q] = 0;
priv->dirty_tx[q] = 0;

- ravb_rx_ring_format(ndev, q);
+ /* Regular RX descriptors have already been initialized by
+ * ravb_rx_ring_refill(), we just need to initialize the final link
+ * descriptor.
+ */
+ rx_desc = ravb_rx_get_desc(priv, q, priv->num_rx_ring[q]);
+ rx_desc->dptr = cpu_to_le32((u32)priv->rx_desc_dma[q]);
+ rx_desc->die_dt = DT_LINKFIX; /* type */

memset(priv->tx_ring[q], 0, tx_ring_size);
/* Build TX ring buffer */
@@ -408,11 +423,9 @@ static void *ravb_alloc_rx_desc(struct net_device *ndev, int q)
static int ravb_ring_init(struct net_device *ndev, int q)
{
struct ravb_private *priv = netdev_priv(ndev);
- const struct ravb_hw_info *info = priv->info;
unsigned int num_tx_desc = priv->num_tx_desc;
unsigned int ring_size;
- struct sk_buff *skb;
- unsigned int i;
+ u32 num_filled;

/* Allocate RX and TX skb rings */
priv->rx_skb[q] = kcalloc(priv->num_rx_ring[q],
@@ -422,12 +435,18 @@ static int ravb_ring_init(struct net_device *ndev, int q)
if (!priv->rx_skb[q] || !priv->tx_skb[q])
goto error;

- for (i = 0; i < priv->num_rx_ring[q]; i++) {
- skb = ravb_alloc_skb(ndev, info, GFP_KERNEL);
- if (!skb)
- goto error;
- priv->rx_skb[q][i] = skb;
- }
+ /* Allocate all RX descriptors. */
+ if (!ravb_alloc_rx_desc(ndev, q))
+ goto error;
+
+ /* Populate RX ring buffer. */
+ priv->dirty_rx[q] = 0;
+ ring_size = priv->info->rx_desc_size * priv->num_rx_ring[q];
+ memset(priv->rx_ring[q].raw, 0, ring_size);
+ num_filled = ravb_rx_ring_refill(ndev, q, priv->num_rx_ring[q],
+ GFP_KERNEL);
+ if (num_filled != priv->num_rx_ring[q])
+ goto error;

if (num_tx_desc > 1) {
/* Allocate rings for the aligned buffers */
@@ -437,12 +456,6 @@ static int ravb_ring_init(struct net_device *ndev, int q)
goto error;
}

- /* Allocate all RX descriptors. */
- if (!ravb_alloc_rx_desc(ndev, q))
- goto error;
-
- priv->dirty_rx[q] = 0;
-
/* Allocate all TX descriptors. */
ring_size = sizeof(struct ravb_tx_desc) *
(priv->num_tx_ring[q] * num_tx_desc + 1);
@@ -762,11 +775,9 @@ static struct sk_buff *ravb_get_skb_gbeth(struct net_device *ndev, int entry,
static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
{
struct ravb_private *priv = netdev_priv(ndev);
- const struct ravb_hw_info *info = priv->info;
struct net_device_stats *stats;
struct ravb_rx_desc *desc;
struct sk_buff *skb;
- dma_addr_t dma_addr;
int rx_packets = 0;
u8 desc_status;
u16 desc_len;
@@ -854,32 +865,9 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
}

/* Refill the RX ring buffers. */
- for (; priv->cur_rx[q] - priv->dirty_rx[q] > 0; priv->dirty_rx[q]++) {
- entry = priv->dirty_rx[q] % priv->num_rx_ring[q];
- desc = &priv->rx_ring[q].desc[entry];
- desc->ds_cc = cpu_to_le16(priv->info->rx_max_desc_use);
-
- if (!priv->rx_skb[q][entry]) {
- skb = ravb_alloc_skb(ndev, info, GFP_ATOMIC);
- if (!skb)
- break;
- dma_addr = dma_map_single(ndev->dev.parent,
- skb->data,
- priv->info->rx_max_frame_size,
- DMA_FROM_DEVICE);
- skb_checksum_none_assert(skb);
- /* We just set the data size to 0 for a failed mapping
- * which should prevent DMA from happening...
- */
- if (dma_mapping_error(ndev->dev.parent, dma_addr))
- desc->ds_cc = cpu_to_le16(0);
- desc->dptr = cpu_to_le32(dma_addr);
- priv->rx_skb[q][entry] = skb;
- }
- /* Descriptor type must be set after all the above writes */
- dma_wmb();
- desc->die_dt = DT_FEMPTY;
- }
+ priv->dirty_rx[q] += ravb_rx_ring_refill(ndev, q,
+ priv->cur_rx[q] - priv->dirty_rx[q],
+ GFP_ATOMIC);

stats->rx_packets += rx_packets;
return rx_packets;
@@ -889,12 +877,10 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
static int ravb_rx_rcar(struct net_device *ndev, int budget, int q)
{
struct ravb_private *priv = netdev_priv(ndev);
- const struct ravb_hw_info *info = priv->info;
struct net_device_stats *stats = &priv->stats[q];
struct ravb_ex_rx_desc *desc;
unsigned int limit, i;
struct sk_buff *skb;
- dma_addr_t dma_addr;
struct timespec64 ts;
int rx_packets = 0;
u8 desc_status;
@@ -964,31 +950,9 @@ static int ravb_rx_rcar(struct net_device *ndev, int budget, int q)
}

/* Refill the RX ring buffers. */
- for (; priv->cur_rx[q] - priv->dirty_rx[q] > 0; priv->dirty_rx[q]++) {
- entry = priv->dirty_rx[q] % priv->num_rx_ring[q];
- desc = &priv->rx_ring[q].ex_desc[entry];
- desc->ds_cc = cpu_to_le16(priv->info->rx_max_desc_use);
-
- if (!priv->rx_skb[q][entry]) {
- skb = ravb_alloc_skb(ndev, info, GFP_ATOMIC);
- if (!skb)
- break; /* Better luck next round. */
- dma_addr = dma_map_single(ndev->dev.parent, skb->data,
- priv->info->rx_max_frame_size,
- DMA_FROM_DEVICE);
- skb_checksum_none_assert(skb);
- /* We just set the data size to 0 for a failed mapping
- * which should prevent DMA from happening...
- */
- if (dma_mapping_error(ndev->dev.parent, dma_addr))
- desc->ds_cc = cpu_to_le16(0);
- desc->dptr = cpu_to_le32(dma_addr);
- priv->rx_skb[q][entry] = skb;
- }
- /* Descriptor type must be set after all the above writes */
- dma_wmb();
- desc->die_dt = DT_FEMPTY;
- }
+ priv->dirty_rx[q] += ravb_rx_ring_refill(ndev, q,
+ priv->cur_rx[q] - priv->dirty_rx[q],
+ GFP_ATOMIC);

stats->rx_packets += rx_packets;
return rx_packets;
--
2.39.2

Next message: Paul Barker: "[net-next PATCH v5 4/7] net: ravb: Refactor GbEth RX code path"
Previous message: Paul Barker: "[net-next PATCH v5 2/7] net: ravb: Align poll function with NAPI docs"
In reply to: Sergey Shtylyov: "Re: [net-next PATCH v5 2/7] net: ravb: Align poll function with NAPI docs"
Next in thread: Paul Barker: "[net-next PATCH v5 4/7] net: ravb: Refactor GbEth RX code path"
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