[Patch net 01/15] net_sched: remove RCU callbacks in basic filter

[Cong Wang]

Replace call_rcu() with synchronize_rcu(), except
in basic_destroy() we have to use list_splice_init_rcu().

Reported-by: Chris Mi <chr...@mellanox.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: John Fastabend <john.fastab...@gmail.com>
Cc: Jamal Hadi Salim <j...@mojatatu.com>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/cls_basic.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c
index d89ebafd2239..11bca8346e0f 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -24,7 +24,6 @@
 struct basic_head {
        u32                     hgenerator;
        struct list_head        flist;
-       struct rcu_head         rcu;
 };
 
 struct basic_filter {
@@ -34,7 +33,6 @@ struct basic_filter {
        struct tcf_result       res;
        struct tcf_proto        *tp;
        struct list_head        link;
-       struct rcu_head         rcu;
 };
 
 static int basic_classify(struct sk_buff *skb, const struct tcf_proto *tp,
@@ -82,10 +80,8 @@ static int basic_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void basic_delete_filter(struct rcu_head *head)
+static void basic_delete_filter(struct basic_filter *f)
 {
-       struct basic_filter *f = container_of(head, struct basic_filter, rcu);
-
        tcf_exts_destroy(&f->exts);
        tcf_em_tree_destroy(&f->ematches);
        kfree(f);
@@ -95,13 +91,16 @@ static void basic_destroy(struct tcf_proto *tp)
 {
        struct basic_head *head = rtnl_dereference(tp->root);
        struct basic_filter *f, *n;
+       LIST_HEAD(local);
+
+       list_splice_init_rcu(&head->flist, &local, synchronize_rcu);
 
-       list_for_each_entry_safe(f, n, &head->flist, link) {
-               list_del_rcu(&f->link);
+       list_for_each_entry_safe(f, n, &local, link) {
+               list_del(&f->link);
                tcf_unbind_filter(tp, &f->res);
-               call_rcu(&f->rcu, basic_delete_filter);
+               basic_delete_filter(f);
        }
-       kfree_rcu(head, rcu);
+       kfree(head);
 }
 
 static int basic_delete(struct tcf_proto *tp, void *arg, bool *last)
@@ -111,7 +110,8 @@ static int basic_delete(struct tcf_proto *tp, void *arg, 
bool *last)
 
        list_del_rcu(&f->link);
        tcf_unbind_filter(tp, &f->res);
-       call_rcu(&f->rcu, basic_delete_filter);
+       synchronize_rcu();
+       basic_delete_filter(f);
        *last = list_empty(&head->flist);
        return 0;
 }
@@ -205,7 +205,8 @@ static int basic_change(struct net *net, struct sk_buff 
*in_skb,
        if (fold) {
                list_replace_rcu(&fold->link, &fnew->link);
                tcf_unbind_filter(tp, &fold->res);
-               call_rcu(&fold->rcu, basic_delete_filter);
+               synchronize_rcu();
+               basic_delete_filter(fold);
        } else {
                list_add_rcu(&fnew->link, &head->flist);
        }
-- 
2.13.0