netdev - [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion

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Message-Id: <20190214074712.17846-10-vladbu@mellanox.com>
Date:   Thu, 14 Feb 2019 09:47:09 +0200
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion

Without rtnl lock protection tcf proto can be deleted concurrently. Check
tcf proto 'deleting' flag after taking tcf spinlock to verify that no
concurrent deletion is in progress. Return EAGAIN error if concurrent
deletion detected, which will cause caller to retry and possibly create new
instance of tcf proto.

Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/cls_flower.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 114cb7876133..bfef7d6c597d 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1497,6 +1497,14 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 	if (!tc_in_hw(fnew->flags))
 		fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW;
 
+	/* tp was deleted concurrently. EAGAIN will cause caller to lookup proto
+	 * again or create new one, if necessary.
+	 */
+	if (tp->deleting) {
+		err = -EAGAIN;
+		goto errout_hw;
+	}
+
 	refcount_inc(&fnew->refcnt);
 	if (fold) {
 		/* Fold filter was deleted concurrently. Retry lookup. */
-- 
2.13.6