Subject: Re: [PATCH v7 10/30] net: wan: Add support for QMC HDLC

From: Jakub Kicinski <[email-masked]>
Date: Fri, 6 Oct 2023 14:47:02 -0700

On Thu, 28 Sep 2023 09:06:28 +0200 Herve Codina wrote:
> +static int qmc_hdlc_close(struct net_device *netdev)
> +{
> +	struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
> +	struct qmc_hdlc_desc *desc;
> +	int i;
> +
> +	netif_stop_queue(netdev);
> +
> +	qmc_chan_stop(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);
> +	qmc_chan_reset(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);

stopping the queue looks a bit racy, a completion may come in 
and restart the queue

> +	for (i = 0; i < ARRAY_SIZE(qmc_hdlc->tx_descs); i++) {
> +		desc = &qmc_hdlc->tx_descs[i];
> +		if (!desc->skb)
> +			continue;
> +		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
> +				 DMA_TO_DEVICE);
> +		kfree_skb(desc->skb);
> +		desc->skb = NULL;
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(qmc_hdlc->rx_descs); i++) {
> +		desc = &qmc_hdlc->rx_descs[i];
> +		if (!desc->skb)
> +			continue;
> +		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
> +				 DMA_FROM_DEVICE);
> +		kfree_skb(desc->skb);
> +		desc->skb = NULL;
> +	}
> +
> +	hdlc_close(netdev);