Re: [PATCH] net: erspan: set lltx to avoid sch_direct_xmit deadlock

["Zhou, Yun" <yun.zhou@windriver.com>]

On 7/9/26 16:16, 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 7/9/26 8:56 AM, Yun Zhou wrote:
>> erspan_xmit() re-enters the network stack via ip_tunnel_xmit(), causing
>> nested acquisition of _xmit_lock on the underlay device while already
>> holding the ERSPAN device's _xmit_lock. Both are ARPHRD_ETHER and share
>> the same lockdep class, creating an ABBA deadlock:
>>
>>    sch_direct_xmit [lock erspan] -> erspan_xmit -> ip_tunnel_xmit ->
>>    ip_output -> __dev_queue_xmit -> sch_direct_xmit [lock underlay]
>>
>> Set dev->lltx = true so HARD_TX_LOCK() skips the spinlock for ERSPAN.
>> This is safe as erspan_xmit() has no shared mutable state: o_seqno is
>> atomic, stats use atomic_long_inc, and dst_cache is per-CPU. GRETAP,
>> the sibling device with identical xmit structure, already sets lltx.
>>
>> Closes: https://syzkaller.appspot.com/bug?extid=9bda1b9fbb7fbdf9b62b
>> Reported-by: syzbot+9bda1b9fbb7fbdf9b62b@syzkaller.appspotmail.com
>> Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
>> Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
> So this is actually a v2 of:
> 
> 20260630183702.170798-2-hemendranaik@gmail.com/20260630183702.170798-2-hemendranaik@gmail.com/
> 
> right?
> 
> please have a look at:
> 
> https://elixir.bootlin.com/linux/v7.1/source/Documentation/process/maintainer-netdev.rst#L434
> 
> any kind of re-submission matters, no matter how trivial is the reason.
> 
> /P
> 

I sincerely apologize for the duplicate patch submission. It was a minor 
oversight caused by a misconfigured Git in my new environment. However, 
it seems this email was sent to hemendranaik@gmail.com, right?

BR,
Yun