742121 – Increase mtu on a physics device,the mtu on vlan device cannot be changed

Bug 742121 - Increase mtu on a physics device,the mtu on vlan device cannot be changed

Summary: Increase mtu on a physics device,the mtu on vlan device cannot be changed

Keywords:
Status:	CLOSED NOTABUG
Alias:	None
Product:	Red Hat Enterprise Linux 6
Classification:	Red Hat
Component:	kernel
Sub Component:
Version:	6.2
Hardware:	All
OS:	Linux
Priority:	medium
Severity:	medium
Target Milestone:	rc
Target Release:	---
Assignee:	Red Hat Kernel Manager
QA Contact:	Red Hat Kernel QE team
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+	depends on / blocked

Reported:	2011-09-29 06:56 UTC by Liang Zheng
Modified:	2013-07-29 01:04 UTC (History)
CC List:	2 users (show)
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed:	2011-11-14 07:02:42 UTC
Target Upstream Version:

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Add an attachment (proposed patch, testcase, etc.)

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

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