Date:   Tue, 7 Mar 2023 14:45:02 +0100
From:   Corinna Vinschen <vinschen@redhat.com>
To:     Lin Ma <linma@zju.edu.cn>
Cc:     jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, richardcochran@gmail.com,
        ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org,
        john.fastabend@gmail.com, intel-wired-lan@lists.osuosl.org,
        pmenzel@molgen.mpg.de, regressions@lists.linux.dev,
        stable@vger.kernel.org
Subject: Re: [PATCH] igb: revert rtnl_lock() that causes deadlock
Message-ID: <ZAc/3oVos9DBx3iR@calimero.vinschen.de>
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Mail-Followup-To: Lin Ma <linma@zju.edu.cn>, jesse.brandeburg@intel.com,
        anthony.l.nguyen@intel.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
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        richardcochran@gmail.com, ast@kernel.org, daniel@iogearbox.net,
        hawk@kernel.org, john.fastabend@gmail.com,
        intel-wired-lan@lists.osuosl.org, pmenzel@molgen.mpg.de,
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 <20230307130547.31446-1-linma@zju.edu.cn>
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On Mar  7 21:05, Lin Ma wrote:
> The commit 6faee3d4ee8b ("igb: Add lock to avoid data race") adds
> rtnl_lock to eliminate a false data race shown below
> 
>  (FREE from device detaching)      |   (USE from netdev core)
> igb_remove                         |  igb_ndo_get_vf_config
>  igb_disable_sriov                 |  vf >= adapter->vfs_allocated_count?
>   kfree(adapter->vf_data)          |
>   adapter->vfs_allocated_count = 0 |
>                                    |    memcpy(... adapter->vf_data[vf]
> 
> The above race will never happen and the extra rtnl_lock causes deadlock
> below
> [...]
> CC: stable@vger.kernel.org
> Fixes: 6faee3d4ee8b ("igb: Add lock to avoid data race")
> Reported-by: Corinna <vinschen@redhat.com>

Thank you, but "Corinna Vinschen", please.


Thanks,
Corinna