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Date:   Fri, 9 Dec 2022 15:57:58 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Yang Yingliang <yangyingliang@huawei.com>
Cc:     <netdev@vger.kernel.org>, <isdn@linux-pingi.de>,
        <davem@davemloft.net>
Subject: Re: [PATCH net 1/3] mISDN: hfcsusb: don't call dev_kfree_skb()
 under spin_lock_irqsave()
Message-ID: <20221209155758.459b858d@kernel.org>
In-Reply-To: <20221207093239.3775457-2-yangyingliang@huawei.com>
References: <20221207093239.3775457-1-yangyingliang@huawei.com>
        <20221207093239.3775457-2-yangyingliang@huawei.com>
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On Wed, 7 Dec 2022 17:32:37 +0800 Yang Yingliang wrote:
>  			spin_lock_irqsave(&hw->lock, flags);
>  			skb_queue_purge(&dch->squeue);

Please take a look at what skb_queue_purge() does.
Perhaps you should create a skb_buff_head on the stack,
skb_queue_splice_init() from the sch->squeue onto that
queue, add the rx_skb and tx_skb into that queue,
then drop the lock and skb_queue_purge() outside the lock.

>  			if (dch->tx_skb) {
> -				dev_kfree_skb(dch->tx_skb);
> +				dev_consume_skb_irq(dch->tx_skb);