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

Steffen Klassert
2025-01-17T07:55:00Z

On Wed, Jan 15, 2025 at 09:19:33AM +0000, Hangbin Liu wrote:
> 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?

Can't you just fix this in bonding? xfrm_timer_handler() can't sleep
anyway, even if you remove the spinlock, it is a timer function.