linux-kernel - Re: [PATCH net] bonding: check xdp prog when set bond mode

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Message-ID: <96a4043b-fdac-4ca1-a7b9-a6352b1d7dfe@blackwall.org>
Date: Fri, 14 Mar 2025 12:44:00 +0200
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Toke Høiland-Jørgensen <toke@...hat.com>,
 Wang Liang <wangliang74@...wei.com>, jv@...sburgh.net,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net,
 hawk@...nel.org, john.fastabend@...il.com, joamaki@...il.com
Cc: yuehaibing@...wei.com, zhangchangzhong@...wei.com,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH net] bonding: check xdp prog when set bond mode

On 3/14/25 12:22 PM, Nikolay Aleksandrov wrote:
> On 3/14/25 12:13 PM, Toke Høiland-Jørgensen wrote:
>> Wang Liang <wangliang74@...wei.com> writes:
>>
>>> Following operations can trigger a warning[1]:
>>>
>>>     ip netns add ns1
>>>     ip netns exec ns1 ip link add bond0 type bond mode balance-rr
>>>     ip netns exec ns1 ip link set dev bond0 xdp obj af_xdp_kern.o sec xdp
>>>     ip netns exec ns1 ip link set bond0 type bond mode broadcast
>>>     ip netns del ns1
>>>
>>> When delete the namespace, dev_xdp_uninstall() is called to remove xdp
>>> program on bond dev, and bond_xdp_set() will check the bond mode. If bond
>>> mode is changed after attaching xdp program, the warning may occur.
>>>
>>> Some bond modes (broadcast, etc.) do not support native xdp. Set bond mode
>>> with xdp program attached is not good. Add check for xdp program when set
>>> bond mode.
>>>
>>>     [1]
>>>     ------------[ cut here ]------------
>>>     WARNING: CPU: 0 PID: 11 at net/core/dev.c:9912 unregister_netdevice_many_notify+0x8d9/0x930
>>>     Modules linked in:
>>>     CPU: 0 UID: 0 PID: 11 Comm: kworker/u4:0 Not tainted 6.14.0-rc4 #107
>>>     Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
>>>     Workqueue: netns cleanup_net
>>>     RIP: 0010:unregister_netdevice_many_notify+0x8d9/0x930
>>>     Code: 00 00 48 c7 c6 6f e3 a2 82 48 c7 c7 d0 b3 96 82 e8 9c 10 3e ...
>>>     RSP: 0018:ffffc90000063d80 EFLAGS: 00000282
>>>     RAX: 00000000ffffffa1 RBX: ffff888004959000 RCX: 00000000ffffdfff
>>>     RDX: 0000000000000000 RSI: 00000000ffffffea RDI: ffffc90000063b48
>>>     RBP: ffffc90000063e28 R08: ffffffff82d39b28 R09: 0000000000009ffb
>>>     R10: 0000000000000175 R11: ffffffff82d09b40 R12: ffff8880049598e8
>>>     R13: 0000000000000001 R14: dead000000000100 R15: ffffc90000045000
>>>     FS:  0000000000000000(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000
>>>     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>     CR2: 000000000d406b60 CR3: 000000000483e000 CR4: 00000000000006f0
>>>     Call Trace:
>>>      <TASK>
>>>      ? __warn+0x83/0x130
>>>      ? unregister_netdevice_many_notify+0x8d9/0x930
>>>      ? report_bug+0x18e/0x1a0
>>>      ? handle_bug+0x54/0x90
>>>      ? exc_invalid_op+0x18/0x70
>>>      ? asm_exc_invalid_op+0x1a/0x20
>>>      ? unregister_netdevice_many_notify+0x8d9/0x930
>>>      ? bond_net_exit_batch_rtnl+0x5c/0x90
>>>      cleanup_net+0x237/0x3d0
>>>      process_one_work+0x163/0x390
>>>      worker_thread+0x293/0x3b0
>>>      ? __pfx_worker_thread+0x10/0x10
>>>      kthread+0xec/0x1e0
>>>      ? __pfx_kthread+0x10/0x10
>>>      ? __pfx_kthread+0x10/0x10
>>>      ret_from_fork+0x2f/0x50
>>>      ? __pfx_kthread+0x10/0x10
>>>      ret_from_fork_asm+0x1a/0x30
>>>      </TASK>
>>>     ---[ end trace 0000000000000000 ]---
>>>
>>> Fixes: 9e2ee5c7e7c3 ("net, bonding: Add XDP support to the bonding driver")
>>> Signed-off-by: Wang Liang <wangliang74@...wei.com>
>>> ---
>>>  drivers/net/bonding/bond_options.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
>>> index 327b6ecdc77e..127181866829 100644
>>> --- a/drivers/net/bonding/bond_options.c
>>> +++ b/drivers/net/bonding/bond_options.c
>>> @@ -868,6 +868,9 @@ static bool bond_set_xfrm_features(struct bonding *bond)
>>>  static int bond_option_mode_set(struct bonding *bond,
>>>  				const struct bond_opt_value *newval)
>>>  {
>>> +	if (bond->xdp_prog)
>>> +		return -EOPNOTSUPP;
>>> +
>>
>> Should we allow changing as long as the new mode also supports XDP?
>>
>> -Toke
>>
>>
> 
> +1
> I think we should allow it, the best way probably is to add a new option 
> BOND_VALFLAG_XDP_UNSUPP (for example) as a bond option flag and to set
> it in bond_options.c for each mode that doesn't support XDP, then you
> can do the check in a generic way (for any option) in
> bond_opt_check_deps. Any bond option that can't be changed with XDP prog

err, I meant any bond option's value that isn't supported with XDP, for
a whole option it would be a bit different

> should have that flag set.
> 
> Cheers,
>  Nik
>