linux-kernel - [PATCH 4.9 58/90] batman-adv: Avoid spurious warnings from bat_v neigh

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Message-Id: <20200319123946.481092472@linuxfoundation.org>
Date:   Thu, 19 Mar 2020 14:00:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sven Eckelmann <sven.eckelmann@...nmesh.com>,
        Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 4.9 58/90] batman-adv: Avoid spurious warnings from bat_v neigh_cmp implementation

From: Sven Eckelmann <sven.eckelmann@...nmesh.com>

commit 6a4bc44b012cbc29c9d824be2c7ab9eac8ee6b6f upstream.

The neighbor compare API implementation for B.A.T.M.A.N. V checks whether
the neigh_ifinfo for this neighbor on a specific interface exists. A
warning is printed when it isn't found.

But it is not called inside a lock which would prevent that this
information is lost right before batadv_neigh_ifinfo_get. It must therefore
be expected that batadv_v_neigh_(cmp|is_sob) might not be able to get the
requested neigh_ifinfo.

A WARN_ON for such a situation seems not to be appropriate because this
will only flood the kernel logs. The warnings must therefore be removed.

Signed-off-by: Sven Eckelmann <sven.eckelmann@...nmesh.com>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/batman-adv/bat_v.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/net/batman-adv/bat_v.c
+++ b/net/batman-adv/bat_v.c
@@ -19,7 +19,6 @@
 #include "main.h"
 
 #include <linux/atomic.h>
-#include <linux/bug.h>
 #include <linux/cache.h>
 #include <linux/errno.h>
 #include <linux/if_ether.h>
@@ -623,11 +622,11 @@ static int batadv_v_neigh_cmp(struct bat
 	int ret = 0;
 
 	ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
-	if (WARN_ON(!ifinfo1))
+	if (!ifinfo1)
 		goto err_ifinfo1;
 
 	ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
-	if (WARN_ON(!ifinfo2))
+	if (!ifinfo2)
 		goto err_ifinfo2;
 
 	ret = ifinfo1->bat_v.throughput - ifinfo2->bat_v.throughput;
@@ -649,11 +648,11 @@ static bool batadv_v_neigh_is_sob(struct
 	bool ret = false;
 
 	ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
-	if (WARN_ON(!ifinfo1))
+	if (!ifinfo1)
 		goto err_ifinfo1;
 
 	ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
-	if (WARN_ON(!ifinfo2))
+	if (!ifinfo2)
 		goto err_ifinfo2;
 
 	threshold = ifinfo1->bat_v.throughput / 4;