netdev - Re: [PATCH net] hinic: fix rewaking txq after netif_tx

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Message-ID: <20200907142834.368b9bae@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 7 Sep 2020 14:28:34 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Luo bin <luobin9@...wei.com>
Cc:     <davem@...emloft.net>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>, <luoxianjun@...wei.com>,
        <yin.yinshi@...wei.com>, <cloud.wangxiaoyun@...wei.com>,
        <chiqijun@...wei.com>
Subject: Re: [PATCH net] hinic: fix rewaking txq after netif_tx_disable

On Mon, 7 Sep 2020 22:15:16 +0800 Luo bin wrote:
> When calling hinic_close in hinic_set_channels, all queues are
> stopped after netif_tx_disable, but some queue may be rewaken in
> free_tx_poll by mistake while drv is handling tx irq. If one queue
> is rewaken core may call hinic_xmit_frame to send pkt after
> netif_tx_disable within a short time which may results in accessing
> memory that has been already freed in hinic_close. So we judge
> whether the netdev is in down state before waking txq in free_tx_poll
> to fix this bug.

The right fix is to call napi_disable() _before_ you call
netif_tx_disable(), not after, like hinic_close() does.