Subject: Re: [PATCH net-next 2/8] bonding: Check return of dev_set_promiscuity/allmulti

From: Wang Chen <[email-masked]>
Date: Fri, 20 Jun 2008 10:56:07 +0800

David Miller said the following on 2008-6-20 10:07:
> From: Wang Chen <[email-masked]>
> Date: Fri, 20 Jun 2008 08:54:42 +0800
> 
>> @@ -419,8 +419,11 @@ static void rlb_teach_disabled_mac_on_primary(struct bonding *bond, u8 addr[])
>>  	}
>>  
>>  	if (!bond->alb_info.primary_is_promisc) {
>> -		bond->alb_info.primary_is_promisc = 1;
>> -		dev_set_promiscuity(bond->curr_active_slave->dev, 1);
>> +		/* dev_set_promiscuity might overflow, check it here */
>> +		if (!dev_set_promiscuity(bond->curr_active_slave->dev, 1))
> 
> Like the first patch, please don't add such comments.
> 
>> @@ -955,6 +965,9 @@ static void bond_mc_swap(struct bonding *bond, struct slave *new_active, struct
>>  	}
>>  
>>  	if (new_active) {
>> +		/* FIXME: promiscuity and allmulti might overflow,
>> +		 * but bond_mc_swap's caller likes quiet handle.
>> +		 */
>>  		if (bond->dev->flags & IFF_PROMISC) {
>>  			dev_set_promiscuity(new_active->dev, 1);
>>  		}
> 
> Please reword this comment.  The issue is that this code path has no
> mechanism to signal errors upstream.  It isn't about a specific type
> of error condition in particular, it's about error handling capabilites
> in general.
> 
>> @@ -3933,6 +3950,10 @@ static void bond_set_multicast_list(struct net_device *bond_dev)
>>  	 * Do promisc before checking multicast_mode
>>  	 */
>>  	if ((bond_dev->flags & IFF_PROMISC) && !(bond->flags & IFF_PROMISC)) {
>> +		/*
>> +		 * FIXME: If bond has multi slaves, how to handle the error
>> +		 * when one of the slaves encounters promiscuity overflow.
>> +		 */
>>  		bond_set_promiscuity(bond, 1);
>>  	}
>>  
> 
> Remove specific reference to promiscuity overflow, these are generic error
> handling issues here regardless of the types of errors that the down
> calls could encounter.
> 
>> @@ -3942,6 +3963,10 @@ static void bond_set_multicast_list(struct net_device *bond_dev)
>>  
>>  	/* set allmulti flag to slaves */
>>  	if ((bond_dev->flags & IFF_ALLMULTI) && !(bond->flags & IFF_ALLMULTI)) {
>> +		/*
>> +		 * FIXME: If bond has multi slaves, how to handle the error
>> +		 * when one of the slaves encounters allmulti overflow.
>> +		 */
>>  		bond_set_allmulti(bond, 1);
>>  	}
> 
> Likewise.
> 

dev_set_promiscuity/allmulti might overflow.
Commit: "netdevice: Fix promiscuity and allmulti overflow" in net-next makes
dev_set_promiscuity/allmulti return error number if overflow happened.

In bond_alb and bond_main, we check all positive increment for promiscuity
and allmulti to get error return.
But there are still two problems left.
1. Some code path has no mechanism to signal errors upstream.
2. If there are multi slaves, it's hard to tell which slaves increment
   promisc/allmulti successfully and which failed.
So I left these problems to be FIXME.
Fortunately, the overflow is very rare case.

Signed-off-by: Wang Chen <[email-masked]>
---
 drivers/net/bonding/bond_alb.c  |    6 ++++--
 drivers/net/bonding/bond_main.c |   39 +++++++++++++++++++++++++++++++--------
 2 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 5a67372..b211486 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -419,8 +419,10 @@ static void rlb_teach_disabled_mac_on_primary(struct bonding *bond, u8 addr[])
 	}
 
 	if (!bond->alb_info.primary_is_promisc) {
-		bond->alb_info.primary_is_promisc = 1;
-		dev_set_promiscuity(bond->curr_active_slave->dev, 1);
+		if (!dev_set_promiscuity(bond->curr_active_slave->dev, 1))
+			bond->alb_info.primary_is_promisc = 1;
+		else
+			bond->alb_info.primary_is_promisc = 0;
 	}
 
 	bond->alb_info.rlb_promisc_timeout_counter = 0;
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 50a40e4..fa3a06d 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -762,39 +762,49 @@ static struct dev_mc_list *bond_mc_list_find_dmi(struct dev_mc_list *dmi, struct
 /*
  * Push the promiscuity flag down to appropriate slaves
  */
-static void bond_set_promiscuity(struct bonding *bond, int inc)
+static int bond_set_promiscuity(struct bonding *bond, int inc)
 {
+	int err = 0;
 	if (USES_PRIMARY(bond->params.mode)) {
 		/* write lock already acquired */
 		if (bond->curr_active_slave) {
-			dev_set_promiscuity(bond->curr_active_slave->dev, inc);
+			err = dev_set_promiscuity(bond->curr_active_slave->dev,
+						  inc);
 		}
 	} else {
 		struct slave *slave;
 		int i;
 		bond_for_each_slave(bond, slave, i) {
-			dev_set_promiscuity(slave->dev, inc);
+			err = dev_set_promiscuity(slave->dev, inc);
+			if (err)
+				return err;
 		}
 	}
+	return err;
 }
 
 /*
  * Push the allmulti flag down to all slaves
  */
-static void bond_set_allmulti(struct bonding *bond, int inc)
+static int bond_set_allmulti(struct bonding *bond, int inc)
 {
+	int err = 0;
 	if (USES_PRIMARY(bond->params.mode)) {
 		/* write lock already acquired */
 		if (bond->curr_active_slave) {
-			dev_set_allmulti(bond->curr_active_slave->dev, inc);
+			err = dev_set_allmulti(bond->curr_active_slave->dev,
+					       inc);
 		}
 	} else {
 		struct slave *slave;
 		int i;
 		bond_for_each_slave(bond, slave, i) {
-			dev_set_allmulti(slave->dev, inc);
+			err = dev_set_allmulti(slave->dev, inc);
+			if (err)
+				return err;
 		}
 	}
+	return err;
 }
 
 /*
@@ -955,6 +965,7 @@ static void bond_mc_swap(struct bonding *bond, struct slave *new_active, struct
 	}
 
 	if (new_active) {
+		/* FIXME: Signal errors upstream. */
 		if (bond->dev->flags & IFF_PROMISC) {
 			dev_set_promiscuity(new_active->dev, 1);
 		}
@@ -1456,12 +1467,16 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	if (!USES_PRIMARY(bond->params.mode)) {
 		/* set promiscuity level to new slave */
 		if (bond_dev->flags & IFF_PROMISC) {
-			dev_set_promiscuity(slave_dev, 1);
+			res = dev_set_promiscuity(slave_dev, 1);
+			if (res)
+				goto err_close;
 		}
 
 		/* set allmulti level to new slave */
 		if (bond_dev->flags & IFF_ALLMULTI) {
-			dev_set_allmulti(slave_dev, 1);
+			res = dev_set_allmulti(slave_dev, 1);
+			if (res)
+				goto err_close;
 		}
 
 		netif_tx_lock_bh(bond_dev);
@@ -3933,6 +3948,10 @@ static void bond_set_multicast_list(struct net_device *bond_dev)
 	 * Do promisc before checking multicast_mode
 	 */
 	if ((bond_dev->flags & IFF_PROMISC) && !(bond->flags & IFF_PROMISC)) {
+		/*
+		 * FIXME: Need to handle the error when one of the multi-slaves
+		 * encounters error.
+		 */
 		bond_set_promiscuity(bond, 1);
 	}
 
@@ -3942,6 +3961,10 @@ static void bond_set_multicast_list(struct net_device *bond_dev)
 
 	/* set allmulti flag to slaves */
 	if ((bond_dev->flags & IFF_ALLMULTI) && !(bond->flags & IFF_ALLMULTI)) {
+		/*
+		 * FIXME: Need to handle the error when one of the multi-slaves
+		 * encounters error.
+		 */
 		bond_set_allmulti(bond, 1);
 	}
 
-- 
1.5.3.4