[PATCH 3.16 014/294] net: bcmgenet: fix dev->stats.tx_bytes accounting

From: Ben Hutchings
Date: Mon Nov 06 2017 - 20:13:30 EST


3.16.50-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Petri Gynther <pgynther@xxxxxxxxxx>

commit 55868120a3e5420bf5aa26a816c07d691579c9e6 upstream.

1. Add bytes_compl local variable to __bcmgenet_tx_reclaim() to collect
transmitted bytes. dev->stats updates can then be moved outside the
while-loop. bytes_compl is also needed for future BQL support.
2. When bcmgenet device uses Tx checksum offload, each transmitted skb
gets an extra 64-byte header prepended to it. Before this header is
prepended to the skb, we need to save the skb "wire" length in
GENET_CB(skb)->bytes_sent, so that proper Tx bytes accounting can
be done in __bcmgenet_tx_reclaim().
3. skb->len covers the entire length of skb, whether it is linear or
fragmented. Thus, when we clean the fragments, do not increase
transmitted bytes.

Fixes: 1c1008c793fa ("net: bcmgenet: add main driver file")
Signed-off-by: Petri Gynther <pgynther@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16:
- Also update tx_packets accounting, as done in upstream commit 4092e6acf5cb
"net: bcmgenet: fix throughtput regression"
- Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -948,6 +948,8 @@ static void __bcmgenet_tx_reclaim(struct
struct device *kdev = &priv->pdev->dev;
struct enet_cb *tx_cb_ptr;
struct netdev_queue *txq;
+ unsigned int pkts_compl = 0;
+ unsigned int bytes_compl = 0;
unsigned int c_index;
unsigned int txbds_ready;
unsigned int txbds_processed = 0;
@@ -969,16 +971,14 @@ static void __bcmgenet_tx_reclaim(struct
while (txbds_processed < txbds_ready) {
tx_cb_ptr = &priv->tx_cbs[ring->clean_ptr];
if (tx_cb_ptr->skb) {
- dev->stats.tx_packets++;
- dev->stats.tx_bytes += tx_cb_ptr->skb->len;
+ pkts_compl++;
+ bytes_compl += GENET_CB(tx_cb_ptr->skb)->bytes_sent;
dma_unmap_single(kdev,
dma_unmap_addr(tx_cb_ptr, dma_addr),
dma_unmap_len(tx_cb_ptr, dma_len),
DMA_TO_DEVICE);
bcmgenet_free_cb(tx_cb_ptr);
} else if (dma_unmap_addr(tx_cb_ptr, dma_addr)) {
- dev->stats.tx_bytes +=
- dma_unmap_len(tx_cb_ptr, dma_len);
dma_unmap_page(kdev,
dma_unmap_addr(tx_cb_ptr, dma_addr),
dma_unmap_len(tx_cb_ptr, dma_len),
@@ -996,6 +996,9 @@ static void __bcmgenet_tx_reclaim(struct
ring->free_bds += txbds_processed;
ring->c_index = (ring->c_index + txbds_processed) & DMA_C_INDEX_MASK;

+ dev->stats.tx_packets += pkts_compl;
+ dev->stats.tx_bytes += bytes_compl;
+
if (ring->free_bds > (MAX_SKB_FRAGS + 1))
ring->int_disable(priv, ring);

@@ -1215,6 +1218,11 @@ static netdev_tx_t bcmgenet_xmit(struct
goto out;
}

+ /* Retain how many bytes will be sent on the wire, without TSB inserted
+ * by transmit checksum offload
+ */
+ GENET_CB(skb)->bytes_sent = skb->len;
+
/* set the SKB transmit checksum */
if (priv->desc_64b_en) {
ret = bcmgenet_put_tx_csum(dev, skb);
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
@@ -504,6 +504,12 @@ struct bcmgenet_hw_params {
u32 flags;
};

+struct bcmgenet_skb_cb {
+ unsigned int bytes_sent; /* bytes on the wire (no TSB) */
+};
+
+#define GENET_CB(skb) ((struct bcmgenet_skb_cb *)((skb)->cb))
+
struct bcmgenet_tx_ring {
spinlock_t lock; /* ring lock */
unsigned int index; /* ring index */