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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Davide Caratti <dcaratti@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 022/215] net/sched: cls_api: increase max_reclassify_loop
Date:   Thu, 15 Jul 2021 20:36:34 +0200
Message-Id: <20210715182602.772139924@linuxfoundation.org>
In-Reply-To: <20210715182558.381078833@linuxfoundation.org>
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From: Davide Caratti <dcaratti@redhat.com>

[ Upstream commit 05ff8435e50569a0a6b95e5ceaea43696e8827ab ]

modern userspace applications, like OVN, can configure the TC datapath to
"recirculate" packets several times. If more than 4 "recirculation" rules
are configured, packets can be dropped by __tcf_classify().
Changing the maximum number of reclassifications (from 4 to 16) should be
sufficient to prevent drops in most use cases, and guard against loops at
the same time.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/sched/cls_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index a281da07bb1d..30090794b791 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1532,7 +1532,7 @@ static inline int __tcf_classify(struct sk_buff *skb,
 				 u32 *last_executed_chain)
 {
 #ifdef CONFIG_NET_CLS_ACT
-	const int max_reclassify_loop = 4;
+	const int max_reclassify_loop = 16;
 	const struct tcf_proto *first_tp;
 	int limit = 0;
 
-- 
2.30.2