Re: [PATCH net] net: bcmasp: fix lost TX wakeup race with lockless queue API

[Nicolai Buchwitz <nb@tipi-net.de>]

Hi Justin

On 28.9.2026 22:18, justin.chen@broadcom.com wrote:
> From: Justin Chen <justin.chen@broadcom.com>
> 
> netif_stop_queue() in bcmasp_xmit() raced with netif_wake_queue() in
> bcmasp_tx_poll(): a reclaim landing between the ring-full check and
> the stop call left the queue stopped despite free descriptors,
> hanging TX until timeout.
> 
> Switch to netif_txq_maybe_stop()/netif_txq_completed_wake() (the
> lockless TX queue API, which also brings in BQL), replace
> tx_spb_ring_full() with a live bcmasp_tx_avail() count.
> 
> Fixes: 490cb412007d ("net: bcmasp: Add support for ASP2.0 Ethernet 
> controller")
> Signed-off-by: Justin Chen <justin.chen@broadcom.com>
> Assisted-by: Claude:claude-sonnet-5
> ---
>  .../net/ethernet/broadcom/asp2/bcmasp_intf.c  | 68 +++++++++++--------

> [...]

>  static struct sk_buff *bcmasp_csum_offload(struct net_device *dev,
> @@ -241,16 +239,18 @@ static netdev_tx_t bcmasp_xmit(struct sk_buff 
> *skb, struct net_device *dev)
>  	struct bcmasp_tx_cb *txcb;
>  	dma_addr_t mapping, valid;
>  	struct bcmasp_desc *desc;
> +	struct netdev_queue *txq;
>  	bool csum_hw = false;
>  	struct device *kdev;
>  	skb_frag_t *frag;
> 
>  	kdev = &intf->parent->pdev->dev;
> +	txq = netdev_get_tx_queue(dev, 0);
> 
>  	nr_frags = skb_shinfo(skb)->nr_frags;
> 
> -	if (tx_spb_ring_full(intf, nr_frags + 1)) {
> -		netif_stop_queue(dev);
> +	if (unlikely(bcmasp_tx_avail(intf) < nr_frags + 1)) {
> +		netif_tx_stop_queue(txq);

nit: AFAIU this is unreachable for now, but to prevent future races 
maybe
better use netif_txq_try_stop()?

> [...]

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>

Thanks,
Nicolai