Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 96AC0C433CA
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Re: [PATCH] p54: avoid accessing the data mapped to streaming DMA
From:   Kalle Valo <kvalo@codeaurora.org>
In-Reply-To: <20200802132949.26788-1-baijiaju@tsinghua.edu.cn>
References: <20200802132949.26788-1-baijiaju@tsinghua.edu.cn>
To:     Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
Cc:     chunkeey@googlemail.com, davem@davemloft.net, kuba@kernel.org,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jia-Ju Bai <baijiaju@tsinghua.edu.cn>
User-Agent: pwcli/0.1.0-git (https://github.com/kvalo/pwcli/) Python/3.5.2
Message-Id: <20200818124147.27D1DC43391@smtp.codeaurora.org>
Date:   Tue, 18 Aug 2020 12:41:47 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Jia-Ju Bai <baijiaju@tsinghua.edu.cn> wrote:

> In p54p_tx(), skb->data is mapped to streaming DMA on line 337:
>   mapping = pci_map_single(..., skb->data, ...);
> 
> Then skb->data is accessed on line 349:
>   desc->device_addr = ((struct p54_hdr *)skb->data)->req_id;
> 
> This access may cause data inconsistency between CPU cache and hardware.
> 
> To fix this problem, ((struct p54_hdr *)skb->data)->req_id is stored in
> a local variable before DMA mapping, and then the driver accesses this
> local variable instead of skb->data.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju@tsinghua.edu.cn>

Can someone review this?

-- 
https://patchwork.kernel.org/patch/11696391/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches