[6/7] get rid of tc_u_common ->rcu

From: Al Viro <viro@zeniv.linux.org.uk>

unused

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 net/sched/cls_u32.c | 1 -
 1 file changed, 1 deletion(-)

On 2018-09-05 3:04 p.m., Al Viro wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
> 
> unused
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

cheers,
jamal

On Wed, Sep 5, 2018 at 12:04 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> From: Al Viro <viro@zeniv.linux.org.uk>
>
> unused
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  net/sched/cls_u32.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> index 8a1a573487bd..be9240ae1417 100644
> --- a/net/sched/cls_u32.c
> +++ b/net/sched/cls_u32.c
> @@ -98,7 +98,6 @@ struct tc_u_common {
>         int                     refcnt;
>         struct idr              handle_idr;
>         struct hlist_node       hnode;
> -       struct rcu_head         rcu;
>  };

Just FYI:

This was added when RCU was introduced to u32 fast path,
it looks like on fast path we never touch tc_u_common, we
only use tp->root, all the rest are slow paths with RTNL lock,
so it is probably fine to just remove it rather than converting
that kfree() to kfree_rcu().

On Thu, Sep 06, 2018 at 09:18:47PM -0700, Cong Wang wrote:
> On Wed, Sep 5, 2018 at 12:04 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > From: Al Viro <viro@zeniv.linux.org.uk>
> >
> > unused
> >
> > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> > ---
> >  net/sched/cls_u32.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> > index 8a1a573487bd..be9240ae1417 100644
> > --- a/net/sched/cls_u32.c
> > +++ b/net/sched/cls_u32.c
> > @@ -98,7 +98,6 @@ struct tc_u_common {
> >         int                     refcnt;
> >         struct idr              handle_idr;
> >         struct hlist_node       hnode;
> > -       struct rcu_head         rcu;
> >  };
> 
> Just FYI:
> 
> This was added when RCU was introduced to u32 fast path,
> it looks like on fast path we never touch tc_u_common, we
> only use tp->root, all the rest are slow paths with RTNL lock,
> so it is probably fine to just remove it rather than converting
> that kfree() to kfree_rcu().

*nod*

In any case, if u32_classify() grows that dereference, we can always
re-add ->rcu at the same time.