netgraph modules won't unload after use
Julian Elischer julian at elischer.org
Wed Mar 18 09:16:15 PDT 2009
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Ash Gokhale wrote:
> 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 at trafmon1:kldload ng_ether
root at 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 at 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 at 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 at trafmon1:klunload ng_hole
klunload: Command not found.
root at trafmon1:kldunload ng_hole
root at trafmon1:kldunload ng_ether
kldunload: can't unload file: Device busy
root at 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 at trafmon1:
this is expected. ng-ether is not unloadable as the connections are
too complicated to unwind easily.. one day....
root at 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.
>
>
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