[PATCH net-next 2/3] bpf, cls: consolidate prog deletion path

[Daniel Borkmann]

Commit 18cdb37ebf4c ("net: sched: do not use tcf_proto 'tp' argument from
call_rcu") removed the last usage of tp from cls_bpf_delete_prog(), so also
remove it from the function as argument to not give a wrong impression. tp
is illegal to access from this callback, since it could already have been
freed.

Refactor the deletion code a bit, so that cls_bpf_destroy() can call into
the same code for prog deletion as cls_bpf_delete() op, instead of having
it unnecessarily duplicated.

Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
 net/sched/cls_bpf.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index c37aa8b..f70e03d 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -241,7 +241,7 @@ static int cls_bpf_init(struct tcf_proto *tp)
        return 0;
 }
 
-static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog 
*prog)
+static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog)
 {
        tcf_exts_destroy(&prog->exts);
 
@@ -255,22 +255,22 @@ static void cls_bpf_delete_prog(struct tcf_proto *tp, 
struct cls_bpf_prog *prog)
        kfree(prog);
 }
 
-static void __cls_bpf_delete_prog(struct rcu_head *rcu)
+static void cls_bpf_delete_prog_rcu(struct rcu_head *rcu)
 {
-       struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
-
-       cls_bpf_delete_prog(prog->tp, prog);
+       __cls_bpf_delete_prog(container_of(rcu, struct cls_bpf_prog, rcu));
 }
 
-static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
+static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog)
 {
-       struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg;
-
        cls_bpf_stop_offload(tp, prog);
        list_del_rcu(&prog->link);
        tcf_unbind_filter(tp, &prog->res);
-       call_rcu(&prog->rcu, __cls_bpf_delete_prog);
+       call_rcu(&prog->rcu, cls_bpf_delete_prog_rcu);
+}
 
+static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
+{
+       __cls_bpf_delete(tp, (struct cls_bpf_prog *) arg);
        return 0;
 }
 
@@ -282,12 +282,8 @@ static bool cls_bpf_destroy(struct tcf_proto *tp, bool 
force)
        if (!force && !list_empty(&head->plist))
                return false;
 
-       list_for_each_entry_safe(prog, tmp, &head->plist, link) {
-               cls_bpf_stop_offload(tp, prog);
-               list_del_rcu(&prog->link);
-               tcf_unbind_filter(tp, &prog->res);
-               call_rcu(&prog->rcu, __cls_bpf_delete_prog);
-       }
+       list_for_each_entry_safe(prog, tmp, &head->plist, link)
+               __cls_bpf_delete(tp, prog);
 
        kfree_rcu(head, rcu);
        return true;
@@ -511,14 +507,14 @@ static int cls_bpf_change(struct net *net, struct sk_buff 
*in_skb,
 
        ret = cls_bpf_offload(tp, prog, oldprog);
        if (ret) {
-               cls_bpf_delete_prog(tp, prog);
+               __cls_bpf_delete_prog(prog);
                return ret;
        }
 
        if (oldprog) {
                list_replace_rcu(&oldprog->link, &prog->link);
                tcf_unbind_filter(tp, &oldprog->res);
-               call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
+               call_rcu(&oldprog->rcu, cls_bpf_delete_prog_rcu);
        } else {
                list_add_rcu(&prog->link, &head->plist);
        }
-- 
1.9.3