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Subject: Re: [PATCH resend 1/3] rtlwifi: rtl8821ae: don't call kfree_skb()
 under spin_lock_irqsave()
To:     Ping-Ke Shih <pkshih@realtek.com>,
        "kvalo@kernel.org" <kvalo@kernel.org>
CC:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        <yangyingliang@huawei.com>
References: <20221206131249.2181693-1-yangyingliang@huawei.com>
 <20221206131249.2181693-2-yangyingliang@huawei.com>
 <758b8caa9e8243bb84471baf50706e6d@realtek.com>
 <c9096bc2-8765-8bf5-484b-da949c99e236@huawei.com>
 <1bbd83a4cd6f48e5878c256c3e8f6334@realtek.com>
From:   Yang Yingliang <yangyingliang@huawei.com>
Message-ID: <0fa6cc09-80b6-94bc-6d0a-dffacf896617@huawei.com>
Date:   Wed, 7 Dec 2022 12:41:19 +0800
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On 2022/12/7 11:52, Ping-Ke Shih wrote:
>> -----Original Message-----
>> From: Yang Yingliang <yangyingliang@huawei.com>
>> Sent: Wednesday, December 7, 2022 11:44 AM
>> To: Ping-Ke Shih <pkshih@realtek.com>; kvalo@kernel.org
>> Cc: linux-wireless@vger.kernel.org; yangyingliang@huawei.com
>> Subject: Re: [PATCH resend 1/3] rtlwifi: rtl8821ae: don't call kfree_skb() under spin_lock_irqsave()
>>
>>
>> On 2022/12/7 11:31, Ping-Ke Shih wrote:
>>>> -----Original Message-----
>>>> From: Yang Yingliang <yangyingliang@huawei.com>
>>>> Sent: Tuesday, December 6, 2022 9:13 PM
>>>> To: Ping-Ke Shih <pkshih@realtek.com>; kvalo@kernel.org
>>>> Cc: linux-wireless@vger.kernel.org; yangyingliang@huawei.com
>>>> Subject: [PATCH resend 1/3] rtlwifi: rtl8821ae: don't call kfree_skb() under spin_lock_irqsave()
>>>>
>>>> It is not allowed to call kfree_skb() from hardware interrupt
>>>> context or with interrupts being disabled. So add all skb to
>>>> a free list, then free them after spin_unlock_irqrestore() at
>>>> once.
>>> The patch doesn't change logic, so it should work. But, I would like to know
>>> if there is a comment about this in kernel code. Could you point it out?
>> You can see comment of dev_kfree_skb_irq() in include/linux/netdevice.h
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/netdevice.h?h=v6
>> .1-rc8
>>
> It seems like we can replace kfree_skb() by dev_kfree_skb_irq(), right?
> But your method is more efficient. Is that your point?
Yes, the SKBs have already been dequeued from the queue, so they can be 
freed together at once.

Thanks,
Yang
>
> Ping-Ke
>