Commit e8d8c5d8 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

bnxt: make sure xmit_more + errors does not miss doorbells 



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: 4d172f21 ("bnxt_en: Implement xmit_more.")
Reviewed-by: default avatarMichael Chan <michael.chan@broadcom.com>
Reviewed-by: default avatarEdwin Peer <edwin.peer@broadcom.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 01cca6b9

drivers/net/ethernet/broadcom/bnxt/bnxt.c

+26 −13
Original line number Diff line number Diff line
@@ -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");
@@ -365,6 +366,13 @@ 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 bool bnxt_txr_netif_try_stop_queue(struct bnxt *bp,

					  struct bnxt_tx_ring_info *txr,

					  struct netdev_queue *txq)
@@ -413,6 +421,10 @@ 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)) {

		/* We must have raced with NAPI cleanup */

		if (net_ratelimit() && txr->kick_pending)

			netif_warn(bp, tx_err, dev,

				   "bnxt: ring busy w/ flush pending!\n");

		if (bnxt_txr_netif_try_stop_queue(bp, txr, txq))

			return NETDEV_TX_BUSY;

	}
@@ -537,21 +549,16 @@ 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 |
@@ -638,13 +645,15 @@ 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);



		bnxt_txr_netif_try_stop_queue(bp, txr, txq);

	}
@@ -659,7 +668,6 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	/* start back at beginning and unmap skb */

	prod = txr->tx_prod;

	tx_buf = &txr->tx_buf_ring[prod];

	tx_buf->skb = NULL;

	dma_unmap_single(&pdev->dev, dma_unmap_addr(tx_buf, mapping),

			 skb_headlen(skb), PCI_DMA_TODEVICE);

	prod = NEXT_TX(prod);
@@ -673,7 +681,12 @@ 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:

	if (txr->kick_pending)

		bnxt_txr_db_kick(bp, txr, txr->tx_prod);

	txr->tx_buf_ring[txr->tx_prod].skb = NULL;

	return NETDEV_TX_OK;

}

drivers/net/ethernet/broadcom/bnxt/bnxt.h

+1 −0
Original line number Diff line number Diff line
@@ -786,6 +786,7 @@ 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];