linux-kernel - [PATCH] hsr: fix don't prune the master node from the node

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Message-Id: <20190522060746.30074-1-andreas.oetken@siemens.com>
Date:   Wed, 22 May 2019 08:07:46 +0200
From:   Andreas Oetken <andreas.oetken@...mens.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     andreas@...ken.name, m-karicheri2@...com, a-kramer@...com,
        Andreas Oetken <andreas.oetken@...mens.com>,
        Arvid Brodin <arvid.brodin@...en.se>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] hsr: fix don't prune the master node from the node_db

Don't prune master node in the hsr_prune_nodes function.
Neither time_in[HSR_PT_SLAVE_A], nor time_in[HSR_PT_SLAVE_B],
will ever be updated by hsr_register_frame_in for the master port.
Thus the master node will be repeatedly pruned leading to
repeated packet loss.
This bug never appeared because the hsr_prune_nodes function
was only called once. Since commit 5150b45fd355
("net: hsr: Fix node prune function for forget time expiry") this issue
is fixed unvealing the issue described above.

Signed-off-by: Andreas Oetken <andreas.oetken@...mens.com>
---
 net/hsr/hsr_framereg.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 9fa9abd83018..2d7a19750436 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -365,6 +365,14 @@ void hsr_prune_nodes(struct timer_list *t)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(node, &hsr->node_db, mac_list) {
+		/* Don't prune own node. Neither time_in[HSR_PT_SLAVE_A]
+		 * nor time_in[HSR_PT_SLAVE_B], will ever be updated for
+		 * the master port. Thus the master node will be repeatedly
+		 * pruned leading to packet loss.
+		 */
+		if (hsr_addr_is_self(hsr, node->macaddress_A))
+			continue;
+
 		/* Shorthand */
 		time_a = node->time_in[HSR_PT_SLAVE_A];
 		time_b = node->time_in[HSR_PT_SLAVE_B];
-- 
2.20.1