Re: [PATCH 6/7] get rid of tc_u_common ->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 [off-list ref] wrote:

quoted

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.