Re: [PATCH net 0/2] bond: fix xfrm offload feature during init

Jianbo Liu
2025-01-09T01:27:01Z

On 1/8/2025 3:14 PM, Hangbin Liu wrote:
> On Wed, Jan 08, 2025 at 11:40:05AM +0800, Jianbo Liu wrote:
>>
>>
>> On 1/8/2025 10:46 AM, Hangbin Liu wrote:
>>> On Mon, Jan 06, 2025 at 10:47:16AM +0000, Hangbin Liu wrote:
>>>> On Thu, Jan 02, 2025 at 11:33:34AM +0800, Jianbo Liu wrote:
>>>>>>> Re-locking doesn't look great, glancing at the code I don't see any
>>>>>>> obvious better workarounds. Easiest fix would be to don't let the
>>>>>>> drivers sleep in the callbacks and then we can go back to a spin lock.
>>>>>>> Maybe nvidia people have better ideas, I'm not familiar with this
>>>>>>> offload.
>>>>>>
>>>>>> I don't know how to disable bonding sleeping since we use mutex_lock now.
>>>>>> Hi Jianbo, do you have any idea?
>>>>>>
>>>>>
>>>>> I think we should allow drivers to sleep in the callbacks. So, maybe it's
>>>>> better to move driver's xdo_dev_state_delete out of state's spin lock.
>>>>
>>>> I just check the code, xfrm_dev_state_delete() and later
>>>> dev->xfrmdev_ops->xdo_dev_state_delete(x) have too many xfrm_state x
>>>> checks. Can we really move it out of spin lock from xfrm_state_delete()
>>>
>>> I tried to move the mutex lock code to a work queue, but found we need to
>>> check (ipsec->xs == xs) in bonding. So we still need xfrm_state x during bond
>>
>> Maybe I miss something, but why need to hold spin lock. You can keep xfrm
>> state by its refcnt.
>
> Do you mean move the xfrm_dev_state_delete() out of spin lock directly like:
>

Yes. Not feasible?

> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
> index 67ca7ac955a3..6881ddeb4360 100644
> --- a/net/xfrm/xfrm_state.c
> +++ b/net/xfrm/xfrm_state.c
> @@ -766,13 +766,6 @@ int __xfrm_state_delete(struct xfrm_state *x)
> if (x->encap_sk)
> sock_put(rcu_dereference_raw(x->encap_sk));
>
> - xfrm_dev_state_delete(x);
> -
> - /* All xfrm_state objects are created by xfrm_state_alloc.
> - * The xfrm_state_alloc call gives a reference, and that
> - * is what we are dropping here.
> - */
> - xfrm_state_put(x);
> err = 0;
> }
>
> @@ -787,8 +780,20 @@ int xfrm_state_delete(struct xfrm_state *x)
> spin_lock_bh(&x->lock);
> err = __xfrm_state_delete(x);
> spin_unlock_bh(&x->lock);
> + if (err)
> + return err;
>
> - return err;
> + if (x->km.state == XFRM_STATE_DEAD) {
> + xfrm_dev_state_delete(x);
> +
> + /* All xfrm_state objects are created by xfrm_state_alloc.
> + * The xfrm_state_alloc call gives a reference, and that
> + * is what we are dropping here.
> + */
> + xfrm_state_put(x);
> + }
> +
> + return 0;
> }
> EXPORT_SYMBOL(xfrm_state_delete);
>
>
> Then why we need the spin lock in xfrm_state_delete?
>

No, we don't need. But I am trying to understand what you said in your
last email about adding a new lock, or unlocking spin lock in
bond_ipsec_del_sa(). Anything I missed?

Thanks!
Jianbo