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Bug 742121

Summary: Increase mtu on a physics device,the mtu on vlan device cannot be changed
Product: Red Hat Enterprise Linux 6 Reporter: Liang Zheng <lzheng>
Component: kernelAssignee: Red Hat Kernel Manager <kernel-mgr>
Status: CLOSED NOTABUG QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.2CC: kzhang, wpan
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-11-14 07:02:42 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Liang Zheng 2011-09-29 06:56:48 UTC
Description of problem:
Default mtu on physics and vlan device are 1500,when change physics mtu to 1600,VLAN device's mtu is still 1500.
Certainly,you can change vlan device's mtu to 1600 manually,
but I think when you change physics device's mtu ,VLAN's mtu should be changed automatically instead of by manually. 

Version-Release number of selected component (if applicable):
kernel 2.6.32-202.el6

How reproducible:
100%

Steps to Reproduce:
1.vconfig add eth4 3
2.ifconfig eth4.3
3.ifconfig eth4 mtu 1600
4.check mtu on eth4.3
  
Actual results:


Expected results:


Additional info:

        case NETDEV_CHANGEMTU:
                for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) {
                        vlandev = vlan_group_get_device(grp, i);
                        if (!vlandev)
                                continue;

                        if (vlandev->mtu <= dev->mtu)
                                continue;

                        dev_set_mtu(vlandev, dev->mtu);
                }

Comment 2 RHEL Program Management 2011-10-07 15:51:40 UTC
Since RHEL 6.2 External Beta has begun, and this bug remains
unresolved, it has been rejected as it is not proposed as
exception or blocker.

Red Hat invites you to ask your support representative to
propose this request, if appropriate and relevant, in the
next release of Red Hat Enterprise Linux.

Comment 3 Weiping Pan 2011-11-14 06:56:38 UTC
Hi, Liang Zheng,

I've posted a patch to upstream, 
http://marc.info/?l=linux-netdev&m=131806865926989&w=2

But it is rejected, and the maintainers do not think this is a bug.

Since we can change vlan device's mtu manually, 
so the current behaviour is fine as it is.

So feel free to close this bug if you agree.

thanks
Weiping Pan