Re: netgraph modules won't unload after use
- From: Ermal Luçi <eri@xxxxxxxxxxx>
- Date: Sat, 28 Mar 2009 20:10:35 +0100
On Wed, Mar 18, 2009 at 5:16 PM, Julian Elischer <julian@xxxxxxxxxxxx> wrote:
Ash Gokhale wrote:Just saw the message.
I'm developing a kernel module that will be doing inspection and needed
access to raw network frames,
so I turned to netgraph as the solution.However it seems that netgraph
will not permit a module
to unload once it's participated in a mkpeer/connect operation. Rebooting
to remove a module is
angrymaking (not like mtx/sleep crashes).
This going into the kernel because my bpf based userland stuff is
probably not going to hold up to the packet rate.
Should I file a PR? Or is there magic in the documentation I havn't found?
I've observed the trouble in 7.0 release, and tonight's 7_RELENG, with
GENERIC + WITNESS/INVARIANTS
The module code ( cobbled together from netgraph/ng_sample.c / ng_echo.c)
http://pastebin.com/m31b6ece6
The module loads and unloads fine until connected to a netgraph hook:
hmm they are supposed to, and they did in the past..
let me check...
root@trafmon1:kldload ng_ether
root@trafmon1:ifconfig
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:11:43:30:fb:8a
inet 10.7.2.3 netmask 0xffffff00 broadcast 10.7.2.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
bge1: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:11:43:30:fb:8b
media: Ethernet autoselect (none)
status: no carrier
fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
ether 00:0e:0c:62:aa:14
inet 10.7.0.101 netmask 0xffffff00 broadcast 10.7.0.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
inet 127.0.0.1 netmask 0xff000000
root@trafmon1:ngctl
+ list
There are 4 total nodes:
Name: bge0 Type: ether ID: 00000002 Num hooks: 0
Name: bge1 Type: ether ID: 00000003 Num hooks: 0
Name: ngctl4252 Type: socket ID: 00000005 Num hooks: 0
Name: fxp0 Type: ether ID: 00000004 Num hooks: 0
+ mkpeer bge0: hole lower hook
+ list
There are 5 total nodes:
Name: <unnamed> Type: hole ID: 00000006 Num hooks: 1
Name: bge0 Type: ether ID: 00000002 Num hooks: 1
Name: bge1 Type: ether ID: 00000003 Num hooks: 0
Name: ngctl4252 Type: socket ID: 00000005 Num hooks: 0
Name: fxp0 Type: ether ID: 00000004 Num hooks: 0
+ shutdown [6]:
+ list
There are 4 total nodes:
Name: bge0 Type: ether ID: 00000002 Num hooks: 0
Name: bge1 Type: ether ID: 00000003 Num hooks: 0
Name: ngctl4252 Type: socket ID: 00000005 Num hooks: 0
Name: fxp0 Type: ether ID: 00000004 Num hooks: 0
+ quit
root@trafmon1:kldstat -v
Id Refs Address Size Name
1 36 0xc0400000 6a9c28 kernel (/boot/kernel/kernel)
[...]
7 1 0xccb16000 4000 ng_ether.ko (/boot/kernel/ng_ether.ko)
Contains modules:
Id Name
246 ng_ether
8 1 0xccb1b000 2000 ng_hole.ko (/boot/kernel/ng_hole.ko)
Contains modules:
Id Name
247 ng_hole
root@trafmon1:klunload ng_hole
klunload: Command not found.
root@trafmon1:kldunload ng_hole
root@trafmon1:kldunload ng_ether
kldunload: can't unload file: Device busy
root@trafmon1:kldstat -v
Id Refs Address Size Name
1 36 0xc0400000 6a9c28 kernel (/boot/kernel/kernel)
[...]
7 1 0xccb16000 4000 ng_ether.ko (/boot/kernel/ng_ether.ko)
Contains modules:
Id Name
246 ng_ether
root@trafmon1:
this is expected. ng-ether is not unloadable as the connections are too
complicated to unwind easily.. one day....
root@trafmon1:
Stop in /root/tmp/food.ko.
Exit 1
#Mar 18 03:14:31 kernel: quiesced
:ro:~/tmp/food.ko:3:14:31:32
Mar 18 03:14:31 kernel: foodmod unloaded
Seems that I can't unload some of the other netgraph types either ( it's
not just me):
#kldunload ng_ether
:ro:~/tmp/food.ko:3:24:07:41
kldunload: can't unload file: Device busy
Exit 1
try unloading a node that IS unloadable..
see the following comment in ng_ehter.c:
/*
* Note that the base code won't try to unload us until
* all nodes have been removed, and that can't happen
* until all Ethernet interfaces are removed. In any
* case, we know there are no nodes left if the action
* is MOD_UNLOAD, so there's no need to detach any nodes.
*/
so we can't run this unless you have removeable ethernet interfaces, and
have removed them.
Actually ng_ether can be unloaded but this is left at your own risk
and there is a comment in code about this.
for each $if in `ifconfig -l`
ngctl shutdown $if:
kldunload ng_ether
This brings the question that should ng_ether be taught about ifnet
events(arrival/departure)?!
--
Ermal
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