netdev - Re: [PATCH v2] net: macb: Relocate mog_init_rings() callback from macb_mac_link_up() to macb

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <d13b87c6-6d53-4a71-9b61-a69e62d555e4@windriver.com>
Date: Fri, 19 Dec 2025 17:16:49 +0800
From: xiaolei wang <xiaolei.wang@...driver.com>
To: Paolo Abeni <pabeni@...hat.com>, nicolas.ferre@...rochip.com,
        claudiu.beznea@...on.dev, andrew+netdev@...n.ch, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, rmk+kernel@...linux.org.uk,
        Kexin.Hao@...driver.com
Cc: netdev@...r.kernel.org, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: macb: Relocate mog_init_rings() callback from
 macb_mac_link_up() to macb_open()


On 12/18/25 20:14, Paolo Abeni wrote:
> CAUTION: This email comes from a non Wind River email account!
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
> On 12/9/25 9:52 AM, Xiaolei Wang wrote:
>> In the non-RT kernel, local_bh_disable() merely disables preemption,
>> whereas it maps to an actual spin lock in the RT kernel. Consequently,
>> when attempting to refill RX buffers via netdev_alloc_skb() in
>> macb_mac_link_up(), a deadlock scenario arises as follows:
>>    Chain caused by macb_mac_link_up():
>>     &bp->lock --> (softirq_ctrl.lock)
>>
>>     Chain caused by macb_start_xmit():
>>     (softirq_ctrl.lock) --> _xmit_ETHER#2 --> &bp->lock
> Including the whole lockdep splat instead of the above would be clearer;
> in fact, I had to fetch the relevant info from there.
OK, I will add all the logs.
>
>> Notably, invoking the mog_init_rings() callback upon link establishment
>> is unnecessary. Instead, we can exclusively call mog_init_rings() within
>> the ndo_open() callback. This adjustment resolves the deadlock issue.
>> Given that mog_init_rings() is only applicable to
>> non-MACB_CAPS_MACB_IS_EMAC cases, we can simply move it to macb_open()
>> and simultaneously eliminate the MACB_CAPS_MACB_IS_EMAC check.
> This part is not clear to me: AFAICS the new code now does such init
> step unconditionally, which looks confusing. I think such step should
> still be under the relevant conditional (or you need to include a
> better/more verbose explanation describing why such check is not really
> needed).

I noticed that the initialization function in 'emac_config' is 
'at91ether_init()',

and 'netdev_ops' is 'at91ether_netdev_ops'. It doesn't use 'macb_open()',

so after moving 'mog_init_rings()' to 'macb_open', we no longer need to 
add this check.

>
>> Fixes: 633e98a711ac ("net: macb: use resolved link config in mac_link_up()")
>> Cc: stable@...r.kernel.org
>> Suggested-by: Kevin Hao <kexin.hao@...driver.com>
>> Signed-off-by: Xiaolei Wang <xiaolei.wang@...driver.com>
> Side note: you still need to include the 'net' tag into the subj prefix.

OK, I will add "net" to the subject in the next version.

thanks

xiaolei

>
> /P
>