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

[Hangbin Liu]

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:

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?

Hangbin