[PATCH net v2] bonding: disable arp and enable mii monitoring when bond change to no uses arp mode

[Ding Tianhong <dingtianhong@huawei.com>]

Because the ARP monitoring is not support for 802.3ad, but I still
could change the mode to 802.3ad from ab mode while ARP monitoring
is running, it is incorrect.

So add a check for 802.3ad in bonding_store_mode to fix the problem,
and make a new macro BOND_NO_USES_ARP() to simplify the code.

v2: according to the Dan Williams's suggestion, bond mode is the most
    important bond option, it should override any of the other sub-options.
    So when the mode is changed, the conficting values should be cleared
    or reset, otherwise the user has to duplicate more operations to modify
    the logic. I disable the arp and enable mii monitoring when the bond mode
    is changed to AB, TB and 8023AD if the arp interval is true.

Suggested-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
---
 drivers/net/bonding/bond_options.c | 13 +++++++++----
 drivers/net/bonding/bonding.h      |  5 +++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 9a5223c..04364f7a 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -45,10 +45,15 @@ int bond_option_mode_set(struct bonding *bond, int mode)
 		return -EPERM;
 	}
 
-	if (BOND_MODE_IS_LB(mode) && bond->params.arp_interval) {
-		pr_err("%s: %s mode is incompatible with arp monitoring.\n",
-		       bond->dev->name, bond_mode_tbl[mode].modename);
-		return -EINVAL;
+	if (BOND_NO_USES_ARP(mode) && bond->params.arp_interval) {
+		pr_info("%s: %s mode is incompatible with arp monitoring, start mii monitoring\n",
+			bond->dev->name, bond_mode_tbl[mode].modename);
+		/* disable arp monitoring */
+		bond->params.arp_interval = 0;
+		/* set miimon to default value */
+		bond->params.miimon = 100;
+		pr_info("%s: Setting MII monitoring interval to %d.\n",
+			bond->dev->name, bond->params.miimon);
 	}
 
 	/* don't cache arp_validate between modes */
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index ca31286..a310fb5 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -55,6 +55,11 @@
 		 ((mode) == BOND_MODE_TLB)          ||	\
 		 ((mode) == BOND_MODE_ALB))
 
+#define BOND_NO_USES_ARP(mode)				\
+		(((mode) == BOND_MODE_8023AD)	||	\
+		 ((mode) == BOND_MODE_TLB)	||	\
+		 ((mode) == BOND_MODE_ALB))
+
 #define TX_QUEUE_OVERRIDE(mode)				\
 			(((mode) == BOND_MODE_ACTIVEBACKUP) ||	\
 			 ((mode) == BOND_MODE_ROUNDROBIN))
-- 
1.8.0