[PATCH net v2 3/4] bnxt: make sure xmit_more + errors does not miss doorbells
From: Jakub Kicinski <kuba@kernel.org>
Date: 2021-08-11 21:38:20
Subsystem:
broadcom bnxt_en 50 gigabit ethernet driver, networking drivers, the rest · Maintainers:
Michael Chan, Pavan Chebbi, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
skbs are freed on error and not put on the ring. We may, however,
be in a situation where we're freeing the last skb of a batch,
and there is a doorbell ring pending because of xmit_more() being
true earlier. Make sure we ring the door bell in such situations.
Since errors are rare don't pay attention to xmit_more() and just
always flush the pending frames.
The busy case should be safe to be left alone because it can
only happen if start_xmit races with completions and they
both enable the queue. In that case the kick can't be pending.
Noticed while reading the code.
Fixes: 4d172f21cefe ("bnxt_en: Implement xmit_more.")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2: - netdev_warn() -> netif_warn() [Edwin]
- use correct prod value [Michael]
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 36 +++++++++++++++--------
drivers/net/ethernet/broadcom/bnxt/bnxt.h | 1 +
2 files changed, 25 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 52f5c8405e76..79bbd6ec7ef7 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c@@ -72,7 +72,8 @@ #include "bnxt_debugfs.h" #define BNXT_TX_TIMEOUT (5 * HZ) -#define BNXT_DEF_MSG_ENABLE (NETIF_MSG_DRV | NETIF_MSG_HW) +#define BNXT_DEF_MSG_ENABLE (NETIF_MSG_DRV | NETIF_MSG_HW | \ + NETIF_MSG_TX_ERR) MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Broadcom BCM573xx network driver");
@@ -367,6 +368,13 @@ static u16 bnxt_xmit_get_cfa_action(struct sk_buff *skb) return md_dst->u.port_info.port_id; } +static void bnxt_txr_db_kick(struct bnxt *bp, struct bnxt_tx_ring_info *txr, + u16 prod) +{ + bnxt_db_write(bp, &txr->tx_db, prod); + txr->kick_pending = 0; +} + static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct bnxt *bp = netdev_priv(dev);
@@ -396,6 +404,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) free_size = bnxt_tx_avail(bp, txr); if (unlikely(free_size < skb_shinfo(skb)->nr_frags + 2)) { netif_tx_stop_queue(txq); + if (net_ratelimit() && txr->kick_pending) + netif_warn(bp, tx_err, dev, "bnxt: ring busy!\n"); return NETDEV_TX_BUSY; }
@@ -516,21 +526,16 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) normal_tx: if (length < BNXT_MIN_PKT_SIZE) { pad = BNXT_MIN_PKT_SIZE - length; - if (skb_pad(skb, pad)) { + if (skb_pad(skb, pad)) /* SKB already freed. */ - tx_buf->skb = NULL; - return NETDEV_TX_OK; - } + goto tx_kick_pending; length = BNXT_MIN_PKT_SIZE; } mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); - if (unlikely(dma_mapping_error(&pdev->dev, mapping))) { - dev_kfree_skb_any(skb); - tx_buf->skb = NULL; - return NETDEV_TX_OK; - } + if (unlikely(dma_mapping_error(&pdev->dev, mapping))) + goto tx_free; dma_unmap_addr_set(tx_buf, mapping, mapping); flags = (len << TX_BD_LEN_SHIFT) | TX_BD_TYPE_LONG_TX_BD |
@@ -617,13 +622,15 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) txr->tx_prod = prod; if (!netdev_xmit_more() || netif_xmit_stopped(txq)) - bnxt_db_write(bp, &txr->tx_db, prod); + bnxt_txr_db_kick(bp, txr, prod); + else + txr->kick_pending = 1; tx_done: if (unlikely(bnxt_tx_avail(bp, txr) <= MAX_SKB_FRAGS + 1)) { if (netdev_xmit_more() && !tx_buf->is_push) - bnxt_db_write(bp, &txr->tx_db, prod); + bnxt_txr_db_kick(bp, txr, prod); netif_tx_stop_queue(txq);
@@ -661,7 +668,12 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) PCI_DMA_TODEVICE); } +tx_free: dev_kfree_skb_any(skb); +tx_kick_pending: + tx_buf->skb = NULL; + if (txr->kick_pending) + bnxt_txr_db_kick(bp, txr, txr->tx_prod); return NETDEV_TX_OK; }
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 9c3324e76ff7..7b989b6e4f6e 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h@@ -799,6 +799,7 @@ struct bnxt_tx_ring_info { u16 tx_prod; u16 tx_cons; u16 txq_index; + u8 kick_pending; struct bnxt_db_info tx_db; struct tx_bd *tx_desc_ring[MAX_TX_PAGES];
--
2.31.1