bonding: don't permit slaves to change their mtu independently

PATCH RESEND In review Ding Tianhong 2 participants 5 messages Jan 25, 2014 – Feb 7, 2014

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Networking Network drivers Bonding driver

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Ding Tianhong

author

2014-01-25 04:58 UTC #0 lore raw

PATCH RESEND 1/1 bonding: don't permit slaves to change their mtu independently

I have come to a conclusion by testing all modes for mtu changing:

1). If the slaves support changing mtu and no need to restart the device,
just like virtual nic, the master will not lost any packages for all mode.

2). If the slaves support changing mtu and need to restart the device,
just like Intel 82599, the AB, 802.3, ALB and TLB mode may lost packages, but other modes could work well.

The reason is that when the slave's mtu has been changed, the slave's hw will restart, if the slave is current active slave, the master may set the slave to backup state and reselect a new slave, after the reselect processing, the master could work again, but if in load-balance mode, the master could select another active slave to send and recv packages.

So the best way to fix the problem is don't permit slave to change their mtu independently.

Cc Jay Vosburgh <[email protected]>

Cc Veaceslav Falico <[email protected]>

Cc Andy Gospodarek <[email protected]>

Signed-off-by Ding Tianhong <[email protected]>

---
 drivers/net/bonding/bond_main.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

drivers/net/bonding/bond_main.c +5 ~~-13~~

index 2ca949f..e127031c 100644
@@ -2808,20 +2808,12 @@ static int bond_slave_netdev_event(unsigned long event,
 		 * ... Or is it this?
 		 */
 		break;
-	case NETDEV_CHANGEMTU:
-		/*
-		 * TODO: Should slaves be allowed to
-		 * independently alter their MTU?  For
-		 * an active-backup bond, slaves need
-		 * not be the same type of device, so
-		 * MTUs may vary.  For other modes,
-		 * slaves arguably should have the
-		 * same MTUs. To do this, we'd need to
-		 * take over the slave's change_mtu
-		 * function for the duration of their
-		 * servitude.
+	case NETDEV_PRECHANGEMTU:
+		/* The master and slaves should have the
+		 * same mtu, so don't permit slaves to
+		 * change their mtu independently.
 		 */
-		break;
+		return NOTIFY_BAD;
 	case NETDEV_CHANGENAME:
 		/* we don't care if we don't have primary set */
 		if (!USES_PRIMARY(bond->params.mode) ||

Signature · 1 line

1.8.0

David Miller

maintainer

2014-02-02 00:53 UTC #1 lore raw

From: Ding Tianhong <[email protected]>
Date: Sat, 25 Jan 2014 12:55:09 +0800

Quoted 16 lines

I have come to a conclusion by testing all modes for mtu changing:
1). If the slaves support changing mtu and no need to restart the device,
just like virtual nic, the master will not lost any packages for all mode.
2). If the slaves support changing mtu and need to restart the device,
just like Intel 82599, the AB, 802.3, ALB and TLB mode may lost packages, but other modes could work well.
The reason is that when the slave's mtu has been changed, the slave's hw will restart, if the slave is current active slave, the master may set the slave to backup state and reselect a new slave, after the reselect processing, the master could work again, but if in load-balance mode, the master could select another active slave to send and recv packages.

Quoted 7 lines

So the best way to fix the problem is don't permit slave to change their mtu independently.
Cc Jay Vosburgh <[email protected]>
Cc Veaceslav Falico <[email protected]>
Cc Andy Gospodarek <[email protected]>
Signed-off-by Ding Tianhong <[email protected]>

This has been rotting in patchwork for a week, and desperately needs someone to review it.

Ding Tianhong

author

2014-02-07 04:20 UTC #2 lore raw

Quoted 22 lines · David Miller

From: Ding Tianhong <[email protected]>
Date: Sat, 25 Jan 2014 12:55:09 +0800
Quoted 19 lines
I have come to a conclusion by testing all modes for mtu changing:
1). If the slaves support changing mtu and no need to restart the device,
just like virtual nic, the master will not lost any packages for all mode.
2). If the slaves support changing mtu and need to restart the device,
just like Intel 82599, the AB, 802.3, ALB and TLB mode may lost packages, but other modes could work well.
The reason is that when the slave's mtu has been changed, the slave's hw will restart, if the slave is current active slave, the master may set the slave to backup state and reselect a new slave, after the reselect processing, the master could work again, but if in load-balance mode, the master could select another active slave to send and recv packages.
So the best way to fix the problem is don't permit slave to change their mtu independently.

Quoted 9 lines

Quoted 4 lines
Cc Jay Vosburgh <[email protected]>
Cc Veaceslav Falico <[email protected]>
Cc Andy Gospodarek <[email protected]>
Signed-off-by Ding Tianhong <[email protected]>
This has been rotting in patchwork for a week, and desperately needs someone to review it.

Self Naked, this patch did not consider the bond dev MTU changing, because if I forbidden the slave to change mtu in any way, the bond will not change its own mtu anymore, so I should think more about this situation. Sorry for the noise.

Regards
Ding

David Miller

maintainer

2014-02-07 03:41 UTC #3 lore raw

In reply to Ding Tianhong

From: Ding Tianhong <[email protected]>
Date: Sat, 25 Jan 2014 12:55:09 +0800

Quoted 16 lines

I have come to a conclusion by testing all modes for mtu changing:
1). If the slaves support changing mtu and no need to restart the device,
just like virtual nic, the master will not lost any packages for all mode.
2). If the slaves support changing mtu and need to restart the device,
just like Intel 82599, the AB, 802.3, ALB and TLB mode may lost packages, but other modes could work well.
The reason is that when the slave's mtu has been changed, the slave's hw will restart, if the slave is current active slave, the master may set the slave to backup state and reselect a new slave, after the reselect processing, the master could work again, but if in load-balance mode, the master could select another active slave to send and recv packages.

Quoted 7 lines

So the best way to fix the problem is don't permit slave to change their mtu independently.
Cc Jay Vosburgh <[email protected]>
Cc Veaceslav Falico <[email protected]>
Cc Andy Gospodarek <[email protected]>
Signed-off-by Ding Tianhong <[email protected]>

Without any review, I'm not applying this patch, sorry.

Ding Tianhong

author

2014-02-07 03:57 UTC #4 lore raw

Quoted 22 lines · David Miller

From: Ding Tianhong <[email protected]>
Date: Sat, 25 Jan 2014 12:55:09 +0800
Quoted 19 lines
I have come to a conclusion by testing all modes for mtu changing:
1). If the slaves support changing mtu and no need to restart the device,
just like virtual nic, the master will not lost any packages for all mode.
2). If the slaves support changing mtu and need to restart the device,
just like Intel 82599, the AB, 802.3, ALB and TLB mode may lost packages, but other modes could work well.
The reason is that when the slave's mtu has been changed, the slave's hw will restart, if the slave is current active slave, the master may set the slave to backup state and reselect a new slave, after the reselect processing, the master could work again, but if in load-balance mode, the master could select another active slave to send and recv packages.
So the best way to fix the problem is don't permit slave to change their mtu independently.

Quoted 8 lines

Quoted 4 lines
Cc Jay Vosburgh <[email protected]>
Cc Veaceslav Falico <[email protected]>
Cc Andy Gospodarek <[email protected]>
Signed-off-by Ding Tianhong <[email protected]>
Without any review, I'm not applying this patch, sorry.

Ok, and I found some new issue for this patch, maybe need more discussion.

Regards
Ding