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

Hangbin Liu
2025-01-15T09:19:44Z

On Wed, Jan 08, 2025 at 07:15:00AM +0000, Hangbin Liu wrote:
> > > > > > 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:
>
> 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);
>

Hi Jianbo,

I talked with Sabrina and it looks we can't simply do this. Because both
xfrm_add_sa_expire() and xfrm_timer_handler() calling __xfrm_state_delete() under
spin lock. If we move the xfrm_dev_state_delete() out of __xfrm_state_delete(),
all the places need to be handled correctly.

At the same time xfrm_timer_handler() calling xfrm_dev_state_update_stats before
__xfrm_state_delete(). Should we also take care of it to make sure the state
change and delete are called at the same time?

Hi Steffen, do you have any comments?

Thanks
Hangbin