[PATCH v2 net-next 3/5] net_sched: convert tcindex to call tcf_exts_destroy from rcu callback

[Alexei Starovoitov]

Adjust destroy path of cls_tcindex to call tcf_exts_destroy() after
rcu grace period.

Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
---
 net/sched/cls_tcindex.c |   29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index a557dbaf5afe..944c8ff45055 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -27,6 +27,7 @@
 struct tcindex_filter_result {
        struct tcf_exts         exts;
        struct tcf_result       res;
+       struct rcu_head         rcu;
 };
 
 struct tcindex_filter {
@@ -133,8 +134,23 @@ static int tcindex_init(struct tcf_proto *tp)
        return 0;
 }
 
-static int
-tcindex_delete(struct tcf_proto *tp, unsigned long arg)
+static void tcindex_destroy_rexts(struct rcu_head *head)
+{
+       struct tcindex_filter_result *r;
+
+       r = container_of(head, struct tcindex_filter_result, rcu);
+       tcf_exts_destroy(&r->exts);
+}
+
+static void tcindex_destroy_fexts(struct rcu_head *head)
+{
+       struct tcindex_filter *f = container_of(head, struct tcindex_filter, 
rcu);
+
+       tcf_exts_destroy(&f->result.exts);
+       kfree(f);
+}
+
+static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
 {
        struct tcindex_data *p = rtnl_dereference(tp->root);
        struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
@@ -162,9 +178,14 @@ found:
                rcu_assign_pointer(*walk, rtnl_dereference(f->next));
        }
        tcf_unbind_filter(tp, &r->res);
-       tcf_exts_destroy(&r->exts);
+       /* all classifiers are required to call tcf_exts_destroy() after rcu
+        * grace period, since converted-to-rcu actions are relying on that
+        * in cleanup() callback
+        */
        if (f)
-               kfree_rcu(f, rcu);
+               call_rcu(&f->rcu, tcindex_destroy_fexts);
+       else
+               call_rcu(&r->rcu, tcindex_destroy_rexts);
        return 0;
 }
 
-- 
1.7.9.5

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