netdev - Re: Should linux send netlink message as it is deleting that routing entry?

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Date:	Fri, 11 Apr 2014 17:15:48 +0800
From:	zhuyj <zyjzyj2000@...il.com>
To:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	ebiederm@...ssion.com, ja@....bg,
	"Yang, Zhangle (Eric)" <Zhangle.Yang@...driver.com>,
	"Tao, Yue" <Yue.Tao@...driver.com>,
	"Zadoyan, Grant" <Grant.Zadoyan@...driver.com>,
	eric.dumazet@...il.com, socketcan@...tkopp.net,
	hannes@...essinduktion.org, cwang@...pensource.com,
	zhuyj <zyjzyj2000@...il.com>
Subject: Re: Should linux send netlink message as it is deleting that routing
 entry?

Hi, all

Please help to look at this problem. And give us an official 
explanation. Should linux send netlink message as it is deleting that 
routing entry?

Thanks a lot.
Zhu Yanjun

On 04/10/2014 04:23 PM, zhuyj wrote:
> Hi, David
>
> With ubuntu 12.04, I run the following to reproduce this defect.
>
> 1) Configure an interface
> ifconfig eth1 150.0.0.1/24 up
>
> 2) Add routing entry via that interface address
> route add -net 200.0.0.0/24 gw 150.0.0.1
>
> 3) Change the ip address on that interface as shown below.
> ifconfig eth1 151.0.0.1/24 up
>
> 4) Check netlink messages with "ip monitor all". There is no route 
> delete netlink message.
>
> [ADDR]Deleted 3: eth1    inet 150.0.0.1/24 brd 150.0.0.255 scope 
> global eth1
> [ROUTE]Deleted 150.0.0.0/24 dev eth1  proto kernel  scope link src 
> 150.0.0.1
> [ROUTE]Deleted broadcast 150.0.0.255 dev eth1  table local  proto 
> kernel  scope link  src 150.0.0.1
> [ROUTE]Deleted broadcast 150.0.0.0 dev eth1  table local  proto 
> kernel  scope link  src 150.0.0.1
> [ROUTE]Deleted local 150.0.0.1 dev eth1  table local  proto kernel 
> scope host  src 150.0.0.1
> [NEIGH]224.0.0.251 dev eth1 lladdr 01:00:5e:00:00:fb NOARP
> [NEIGH]224.0.0.22 dev eth1 lladdr 01:00:5e:00:00:16 NOARP
> [ADDR]3: eth1    inet 151.0.0.1/16 brd 151.0.255.255 scope global eth1
> [ROUTE]local 151.0.0.1 dev eth1  table local  proto kernel  scope 
> host  src 151.0.0.1
> [ROUTE]broadcast 151.0.255.255 dev eth1  table local  proto kernel 
> scope link  src 151.0.0.1
> [ROUTE]151.0.0.0/16 dev eth1  proto kernel  scope link  src 151.0.0.1
> [ROUTE]broadcast 151.0.0.0 dev eth1  table local  proto kernel scope 
> link  src 151.0.0.1
> [ADDR]Deleted 3: eth1    inet 151.0.0.1/16 brd 151.0.255.255 scope 
> global eth1
> [ROUTE]Deleted 151.0.0.0/16 dev eth1  proto kernel  scope link src 
> 151.0.0.1
> [ROUTE]Deleted broadcast 151.0.255.255 dev eth1  table local proto 
> kernel  scope link  src 151.0.0.1
> [ROUTE]Deleted broadcast 151.0.0.0 dev eth1  table local  proto 
> kernel  scope link  src 151.0.0.1
> [ROUTE]Deleted local 151.0.0.1 dev eth1  table local  proto kernel 
> scope host  src 151.0.0.1
> [NEIGH]224.0.0.22 dev eth1 lladdr 01:00:5e:00:00:16 NOARP
> [ADDR]3: eth1    inet 151.0.0.1/24 brd 151.0.0.255 scope global eth1
> [ROUTE]local 151.0.0.1 dev eth1  table local  proto kernel  scope 
> host  src 151.0.0.1
> [ROUTE]broadcast 151.0.0.255 dev eth1  table local  proto kernel scope 
> link  src 151.0.0.1
> [ROUTE]151.0.0.0/24 dev eth1  proto kernel  scope link  src 151.0.0.1
> [ROUTE]broadcast 151.0.0.0 dev eth1  table local  proto kernel scope 
> link  src 151.0.0.1
>
> There is no netlink message to notify that 200.0.0.0/24 is deleted. 
> But in fact, this 200.0.0.0/24 route item disappears.
>
> I checked the source code, and I found the following is the process to 
> delete static routes when the attached interface is deleted.
>
>  1)               |  fib_netdev_event() {
>  1)               |    fib_disable_ip() {
>  1)   1.284 us    |      fib_sync_down_dev();
>  1)               |      fib_flush() {
>  1)               |        fib_table_flush() {
>  1)   0.129 us    |          fib_release_info();
>  1)   0.351 us    |          fib_release_info();
>  1)   4.605 us    |        }
>  1)               |        fib_table_flush() {
>  1)   0.096 us    |          fib_release_info();
>  1)   0.255 us    |          fib_release_info();
>  1)   4.770 us    |        }
>  1) + 11.787 us   |      }
>  1) ! 315.273 us  |    }
>  1) ! 315.888 us  |  }
>
> But there is no netlink message sent here.
>
> Should linux send netlink message as it is deleting that 200.0.0.0/24 
> routing entry?
>
> Best Regards!
> Zhu Yanjun
>
>

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