netdev - Re: [PATCH] wifi: brcmfmac: unmap dma buffer in brcmf_msgbuf_alloc

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Date:   Thu, 22 Dec 2022 16:52:25 +0800
From:   shaozhengchao <shaozhengchao@...wei.com>
To:     Kalle Valo <kvalo@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC:     <netdev@...r.kernel.org>, <linux-wireless@...r.kernel.org>,
        <brcm80211-dev-list.pdl@...adcom.com>,
        <SHA-cyfmac-dev-list@...ineon.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <aspriel@...il.com>, <franky.lin@...adcom.com>,
        <hante.meuleman@...adcom.com>, <wright.feng@...ress.com>,
        <chi-hsien.lin@...ress.com>, <a.fatoum@...gutronix.de>,
        <alsi@...g-olufsen.dk>, <pieterpg@...adcom.com>,
        <dekim@...adcom.com>, <linville@...driver.com>,
        <weiyongjun1@...wei.com>, <yuehaibing@...wei.com>
Subject: Re: [PATCH] wifi: brcmfmac: unmap dma buffer in
 brcmf_msgbuf_alloc_pktid()



On 2022/12/22 16:46, Kalle Valo wrote:
> Sebastian Andrzej Siewior <bigeasy@...utronix.de> writes:
> 
>> On 2022-12-21 18:33:06 [+0000], Kalle Valo wrote:
>>> Zhengchao Shao <shaozhengchao@...wei.com> wrote:
>>>
>>>> After the DMA buffer is mapped to a physical address, address is stored
>>>> in pktids in brcmf_msgbuf_alloc_pktid(). Then, pktids is parsed in
>>>> brcmf_msgbuf_get_pktid()/brcmf_msgbuf_release_array() to obtain physaddr
>>>> and later unmap the DMA buffer. But when count is always equal to
>>>> pktids->array_size, physaddr isn't stored in pktids and the DMA buffer
>>>> will not be unmapped anyway.
>>>>
>>>> Fixes: 9a1bb60250d2 ("brcmfmac: Adding msgbuf protocol.")
>>>> Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
>>>
>>> Can someone review this?
>>
>> After looking at the code, that skb is mapped but not inserted into the
>> ringbuffer in this condition. The function returns with an error and the
>> caller will free that skb (or add to a list for later). Either way the
>> skb remains mapped which is wrong. The unmap here is the right thing to
>> do.
>>
>> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> 
> Thanks for the review, very much appreciated.
> 

Thank you very much.

Zhengchao Shao