[PATCH net-next v2 01/15] net: sched: act_bpf: remove dependency on rtnl lock

[Vlad Buslov <vladbu@mellanox.com>]

Use tcf spinlock to protect bpf action private data from concurrent
modification during dump and init. Remove rtnl lock assertion that is no
longer necessary.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
---
 net/sched/act_bpf.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index 6203eb075c9a..9e8a33f9fee3 100644
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -143,11 +143,12 @@ static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 		.index   = prog->tcf_index,
 		.refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
 		.bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
-		.action  = prog->tcf_action,
 	};
 	struct tcf_t tm;
 	int ret;
 
+	spin_lock(&prog->tcf_lock);
+	opt.action = prog->tcf_action;
 	if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 		goto nla_put_failure;
 
@@ -163,9 +164,11 @@ static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 			  TCA_ACT_BPF_PAD))
 		goto nla_put_failure;
 
+	spin_unlock(&prog->tcf_lock);
 	return skb->len;
 
 nla_put_failure:
+	spin_unlock(&prog->tcf_lock);
 	nlmsg_trim(skb, tp);
 	return -1;
 }
@@ -264,7 +267,7 @@ static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 {
 	cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 	/* updates to prog->filter are prevented, since it's called either
-	 * with rtnl lock or during final cleanup in rcu callback
+	 * with tcf lock or during final cleanup in rcu callback
 	 */
 	cfg->filter = rcu_dereference_protected(prog->filter, 1);
 
@@ -336,8 +339,8 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 		goto out;
 
 	prog = to_bpf(*act);
-	ASSERT_RTNL();
 
+	spin_lock(&prog->tcf_lock);
 	if (res != ACT_P_CREATED)
 		tcf_bpf_prog_fill_cfg(prog, &old);
 
@@ -349,6 +352,7 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 
 	prog->tcf_action = parm->action;
 	rcu_assign_pointer(prog->filter, cfg.filter);
+	spin_unlock(&prog->tcf_lock);
 
 	if (res == ACT_P_CREATED) {
 		tcf_idr_insert(tn, *act);
-- 
2.7.5