Re: [Issue report] drivers/ftgmac100: DHCP occasionally fails during boot up or link down/up

[Heyi Guo <guoheyi@linux.alibaba.com>]

Thanks for your advice. Let me take a try again :)

Heyi

在 2022/2/22 上午6:09, Andrew Lunn 写道:
>> [   16.872475]  Possible unsafe locking scenario:
>> [   16.872475]
>> [   16.872478]        CPU0                    CPU1
>> [   16.872482]        ----                    ----
>> [   16.872485]   lock(&dev->lock);
>> [   16.872495]                                lock(rtnl_mutex);
>> [   16.872505] lock(&dev->lock);
> It looks like the whitespace got messed up here, and it should
> actually be:
>> [   16.872505]                                lock(&dev->lock);
>> [   16.872513]   lock(rtnl_mutex);
> So if up calls open() which first takes rtnl and then the
> phydev->lock.
>
> adjust link is called with phydev->lock already held and it then takes
> the rtnl. Deadlock.
>
> During the adjust_list callback, the phydev lock is held so the
> contents of phydev are consistent. What you could do is make a copy of
> what you need and then release phydev lock. You can then take rtnl and
> do the reset. Once the reset is finished, program MAC with the copy
> you took from phydev. Then lock phydev again, and return.
>
>      Andrew