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

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Message-ID: <YhE2wl7XcTUQvEd4@lunn.ch>
Date:   Sat, 19 Feb 2022 19:28:18 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Heyi Guo <guoheyi@...ux.alibaba.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Dylan Hung <dylan_hung@...eedtech.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Issue report] drivers/ftgmac100: DHCP occasionally fails during
 boot up or link down/up

On Sat, Feb 19, 2022 at 06:08:35PM +0800, Heyi Guo wrote:
> Hi Andrew,
> 
> The DHCP issue is gone after applying below patch. I put the lock statements
> outside of the pure reset function, for the phydev lock has been acquired
> before calling adjust_link. The lock order in ftgmac100_reset_task() was
> also changed, to make it the same as the lock procedure in adjust_link, in
> which the phydev is locked first and then rtnl_lock. I'm not quite sure
> whether it will bring in any potential dead lock. Any advice?

Did you run the code with CONFIG_PROVE_LOCKING enabled. That will help
detect possible deadlock situations.

       Andrew