linux-kernel - [PATCH net v4 2/3] bonding: 802.3ad: fix no transmission of LACPDUs

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Date:   Thu, 18 Aug 2022 10:41:11 -0400
From:   Jonathan Toppins <jtoppins@...hat.com>
To:     netdev@...r.kernel.org, jay.vosburgh@...onical.com
Cc:     liuhangbin@...il.com, Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net v4 2/3] bonding: 802.3ad: fix no transmission of LACPDUs

This is caused by the global variable ad_ticks_per_sec being zero as
demonstrated by the reproducer script discussed below. This causes
all timer values in __ad_timer_to_ticks to be zero, resulting
in the periodic timer to never fire.

To reproduce:
Run the script in
`tools/testing/selftests/drivers/net/bonding/bond-break-lacpdu-tx.sh` which
puts bonding into a state where it never transmits LACPDUs.

line 44: ip link add fbond type bond mode 4 miimon 200 \
            xmit_hash_policy 1 ad_actor_sys_prio 65535 lacp_rate fast
setting bond param: ad_actor_sys_prio
given:
    params.ad_actor_system = 0
call stack:
    bond_option_ad_actor_sys_prio()
    -> bond_3ad_update_ad_actor_settings()
       -> set ad.system.sys_priority = bond->params.ad_actor_sys_prio
       -> ad.system.sys_mac_addr = bond->dev->dev_addr; because
            params.ad_actor_system == 0
results:
     ad.system.sys_mac_addr = bond->dev->dev_addr

line 48: ip link set fbond address 52:54:00:3B:7C:A6
setting bond MAC addr
call stack:
    bond->dev->dev_addr = new_mac

line 52: ip link set fbond type bond ad_actor_sys_prio 65535
setting bond param: ad_actor_sys_prio
given:
    params.ad_actor_system = 0
call stack:
    bond_option_ad_actor_sys_prio()
    -> bond_3ad_update_ad_actor_settings()
       -> set ad.system.sys_priority = bond->params.ad_actor_sys_prio
       -> ad.system.sys_mac_addr = bond->dev->dev_addr; because
            params.ad_actor_system == 0
results:
     ad.system.sys_mac_addr = bond->dev->dev_addr

line 60: ip link set veth1-bond down master fbond
given:
    params.ad_actor_system = 0
    params.mode = BOND_MODE_8023AD
    ad.system.sys_mac_addr == bond->dev->dev_addr
call stack:
    bond_enslave
    -> bond_3ad_initialize(); because first slave
       -> if ad.system.sys_mac_addr != bond->dev->dev_addr
          return
results:
     Nothing is run in bond_3ad_initialize() because dev_addr equals
     sys_mac_addr leaving the global ad_ticks_per_sec zero as it is
     never initialized anywhere else.

The if check around the contents of bond_3ad_initialize() is no longer
needed due to commit 5ee14e6d336f ("bonding: 3ad: apply ad_actor settings
changes immediately") which sets ad.system.sys_mac_addr if any one of
the bonding parameters whos set function calls
bond_3ad_update_ad_actor_settings(). This is because if
ad.system.sys_mac_addr is zero it will be set to the current bond mac
address, this causes the if check to never be true.

Fixes: 5ee14e6d336f ("bonding: 3ad: apply ad_actor settings changes immediately")
Signed-off-by: Jonathan Toppins <jtoppins@...hat.com>
---

Notes:
    v2:
     * split this fix from the reproducer
    v3:
     * rebased to latest net/master
    v4:
     * instead of setting ad_ticks_per_sec remove the if statement around the
       body of the function of bond_3ad_initialize().

 drivers/net/bonding/bond_3ad.c | 38 ++++++++++++++--------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index d7fb33c078e8..1f0120cbe9e8 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2007,30 +2007,24 @@ void bond_3ad_initiate_agg_selection(struct bonding *bond, int timeout)
  */
 void bond_3ad_initialize(struct bonding *bond, u16 tick_resolution)
 {
-	/* check that the bond is not initialized yet */
-	if (!MAC_ADDRESS_EQUAL(&(BOND_AD_INFO(bond).system.sys_mac_addr),
-				bond->dev->dev_addr)) {
-
-		BOND_AD_INFO(bond).aggregator_identifier = 0;
-
-		BOND_AD_INFO(bond).system.sys_priority =
-			bond->params.ad_actor_sys_prio;
-		if (is_zero_ether_addr(bond->params.ad_actor_system))
-			BOND_AD_INFO(bond).system.sys_mac_addr =
-			    *((struct mac_addr *)bond->dev->dev_addr);
-		else
-			BOND_AD_INFO(bond).system.sys_mac_addr =
-			    *((struct mac_addr *)bond->params.ad_actor_system);
+	BOND_AD_INFO(bond).aggregator_identifier = 0;
+	BOND_AD_INFO(bond).system.sys_priority =
+		bond->params.ad_actor_sys_prio;
+	if (is_zero_ether_addr(bond->params.ad_actor_system))
+		BOND_AD_INFO(bond).system.sys_mac_addr =
+		    *((struct mac_addr *)bond->dev->dev_addr);
+	else
+		BOND_AD_INFO(bond).system.sys_mac_addr =
+		    *((struct mac_addr *)bond->params.ad_actor_system);
 
-		/* initialize how many times this module is called in one
-		 * second (should be about every 100ms)
-		 */
-		ad_ticks_per_sec = tick_resolution;
+	/* initialize how many times this module is called in one
+	 * second (should be about every 100ms)
+	 */
+	ad_ticks_per_sec = tick_resolution;
 
-		bond_3ad_initiate_agg_selection(bond,
-						AD_AGGREGATOR_SELECTION_TIMER *
-						ad_ticks_per_sec);
-	}
+	bond_3ad_initiate_agg_selection(bond,
+					AD_AGGREGATOR_SELECTION_TIMER *
+					ad_ticks_per_sec);
 }
 
 /**
-- 
2.31.1