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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 30 Jun 2022 15:59:48 +0200
Message-ID: <CANn89iJ-2BTR1SfFBbNG3jSgHK-TuRE_J-Khbbednu=pWnFtmw@mail.gmail.com>
Subject: Re: [PATCH] net: hinic: avoid kernel hung in hinic_get_stats64()
To:     maqiao <mqaio@linux.alibaba.com>
Cc:     David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, gustavoars@kernel.org,
        cai.huoqing@linux.dev, Aviad Krawczyk <aviad.krawczyk@huawei.com>,
        zhaochen6@huawei.com, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jun 30, 2022 at 3:57 PM maqiao <mqaio@linux.alibaba.com> wrote:
>
>
>
> =E5=9C=A8 2022/6/30 =E4=B8=8B=E5=8D=886:23, Eric Dumazet =E5=86=99=E9=81=
=93:

> > Note: The following is racy, because multiple threads can call
> > hinic_get_stats64() at the same time.
> > It needs a loop, see include/linux/u64_stats_sync.h for detail.
> Thanks for reminding, and I noticed that nic_tx_stats/nic_rx_stats has
> been protected by u64_stats_sync in update_t/rx_stats(), it seems that
> it's unnecessary to use spinlock in update_nic_stats().

It is necessary to use the spinlock to protect writers among themselves.


>
> I will send v2 as soon as possible, thanks.