Re: [PATCH] wifi: rtl8xxxu: don't call dev_kfree_skb() under spin_lock_irqsave()

[Yang Yingliang <yangyingliang@huawei.com>]

On 2022/12/8 8:38, Ping-Ke Shih wrote:
>> -----Original Message-----
>> From: Yang Yingliang <yangyingliang@huawei.com>
>> Sent: Wednesday, December 7, 2022 10:38 PM
>> To: Jes.Sorensen@gmail.com; kvalo@kernel.org
>> Cc: linux-wireless@vger.kernel.org
>> Subject: [PATCH] wifi: rtl8xxxu: don't call dev_kfree_skb() under spin_lock_irqsave()
>>
>> It is not allowed to call consume_skb() from hardware interrupt context
>                              ^^^^^^^^^^^^^ kfree_skb()?
> because this patch is to replace dev_kfree_skb().
>
>> or with interrupts being disabled. So replace dev_kfree_skb() with
>> dev_consume_skb_irq() under spin_lock_irqsave(). Compile tested only.
>>
>> Fixes: 26f1fad29ad9 ("New driver: rtl8xxxu (mac80211)")
>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>> ---
>>   drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>> b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>> index ac641a56efb0..d0600af5bef4 100644
>> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>> @@ -5274,7 +5274,7 @@ static void rtl8xxxu_queue_rx_urb(struct rtl8xxxu_priv *priv,
>>   		pending = priv->rx_urb_pending_count;
>>   	} else {
>>   		skb = (struct sk_buff *)rx_urb->urb.context;
>> -		dev_kfree_skb(skb);
>> +		dev_consume_skb_irq(skb);
> Why not dev_kfree_skb_irq() instead? any reason?
#define dev_kfree_skb(a)        consume_skb(a)
dev_kfree_skb() is consume_skb(), so use dev_consume_skb_irq() instead.

static inline void dev_kfree_skb_irq(struct sk_buff *skb)
{
         __dev_kfree_skb_irq(skb, SKB_REASON_DROPPED);
}

static inline void dev_consume_skb_irq(struct sk_buff *skb)
{
         __dev_kfree_skb_irq(skb, SKB_REASON_CONSUMED);
}
They have different free reasons.

Thanks,
Yang
>
>>   		usb_free_urb(&rx_urb->urb);
>>   	}
>>
>> --
>> 2.25.1
>>
>>
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> .