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bnxt_en: Write doorbell when linearizing skb fails

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When the driver is handed a burst of packets, the doorbell is deferred
until the end. If the last packet has a huge number of frags, but fails
to linearize, the doorbell will not be written adding latency on TX for
any packets in the ring and holding their DMA mappings until the next
TX. Note that the queue is not stopped, so this issue would delay
pending BDs until the next TX.

This issue was discovered by Sashiko and reading the code verifies that,
while unlikely, it is possible.

Fix this by jumping to tx_free, which replicates the same pre-existing
logic but also writes the doorbell.

Fixes: b91e821294 ("bnxt_en: Linearize TX SKB if the fragments exceed the max")
Cc: stable@vger.kernel.org
Signed-off-by: Joe Damato <joe@dama.to>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Andy Gospodarek <gospo@broadcom.com>
Link: https://patch.msgid.link/20260826000234.2031564-1-joe@dama.to
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Joe Damato 2026-08-25 17:02:33 -07:00 committed by Paolo Abeni
parent cec261b0b4
commit 00eeab0c64
1 changed files with 2 additions and 5 deletions
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7
drivers/net/ethernet/broadcom/bnxt/bnxt.c
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@ -502,11 +502,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
if (skb_shinfo(skb)->nr_frags > TX_MAX_FRAGS) {
netdev_warn_once(dev, "SKB has too many (%d) fragments, max supported is %d. SKB will be linearized.\n",
skb_shinfo(skb)->nr_frags, TX_MAX_FRAGS);
if (skb_linearize(skb)) {
dev_kfree_skb_any(skb);
dev_core_stats_tx_dropped_inc(dev);
return NETDEV_TX_OK;
}
if (skb_linearize(skb))
goto tx_free;
}
#endif
if (skb_is_gso(skb) &&