building af_packet as a kernel module
Hello, I have tried to set CONFIG_PACKET=m in kernel 4.11 and rebuilt the kernel and rebooted. I am using Ubuntu 16.04. After reboot, the af_packet.ko kernel module is loaded: lsmod shows: af_packet 45056 2 But I cannot remove it: rmmod af_packet rmmod: ERROR: Module af_packet is in use I want to be able to rmmod it, for adding debug printing, etc. How can I find which applications uses it ? (So I will be able to stop them, rmmod af_packet, and then insmod it again)? Regards, Kevin
On Fri, Jun 30, 2017 at 12:06 AM, Kevin Wilson <wkevils@gmail.com> wrote: Hello, I have tried to set CONFIG_PACKET=m in kernel 4.11 and rebuilt the kernel and rebooted. I am using Ubuntu 16.04.
After reboot, the af_packet.ko kernel module is loaded: lsmod shows: af_packet 45056 2
But I cannot remove it: rmmod af_packet rmmod: ERROR: Module af_packet is in use
I want to be able to rmmod it, for adding debug printing, etc.
How can I find which applications uses it ? (So I will be able to stop them, rmmod af_packet, and then insmod it again)?
Regards, Kevin
Hello Kevin, Quick fix and short answer to your problem is to disable internet. run this in a shell/terminal: /sbin/ifconfig etho0 down Now check lsmod again, once internet is disabled the used by column which lsmod reports as af_packet being used by 2 devices/processes/whatever... will show 0. Now when you sbin/rmmod af-packet it will work and unload af_packet. Do whatever debug printing you have to.... sbin/insmod af_packet enable internet by running : /sbin/ifconfig etho0 down now check dmesg or what ever you use. Wash, rinse then repeat as needed. The answer to your question "How can I find which applications uses it ?" is something "I" have been trying to figure out for the last 9 odd years. Maybe folks with more experience can shed some light on how to go about doing this ? More experienced equates to = Valdis / Gregkh / DerRichard / Realtime localmodconfig Steve Rostedt and too many others to name.... :) Hope this helps - Aruna
On 03.07.2017 16:02, Aruna Hewapathirane wrote:
[...] enable internet by running : /sbin/ifconfig etho0 down
sudo /sbin/ifconfig eno1 up or eth0 or whatever your system names its ethernet devices
[...]
List net interfaces with: sudo /sbin/ifconfig -- Best regards, Kamil Konieczny Samsung R&D Institute Poland
Hi, On 30.06.2017 06:06, Kevin Wilson wrote:
[...] I am using Ubuntu 16.04.
After reboot, the af_packet.ko kernel module is loaded: lsmod
af_packet 45056 2
But I cannot remove it: rmmod af_packet rmmod: ERROR: Module af_packet is in use
I want to be able to rmmod it, for adding debug printing, etc. [...] I googled this:
https://stackoverflow.com/questions/448999/is-there-a-way-to-figure-out-what... and short answer is to use 'lsof' command (ls open files), if lsmod fails to give ref info -- Best regards, Kamil Konieczny Samsung R&D Institute Poland
On Mon, 03 Jul 2017 16:36:01 +0200, Kamil Konieczny said:
https://stackoverflow.com/questions/448999/is-there-a-way-to-figure-out-what...
and short answer is to use 'lsof' command (ls open files), if lsmod fails to give ref info
That's the short - and incorrect - answer. The long and *much* more correct answer is on that link, and talks about the kernel tracing facility. lsof only helps if the module is in use due to a direct reference on a filesystem object (something you can /bin/ls). So for instance, if you're trying to figure out why a serial driver won't unload, finding that somebody has /dev/ttyUSB0 open may help. But it *won't* help if it's a an indirect reference (a filesystem object is open, but it's a filesystem on a USB memory device, and the mount of /dev/sdb1 ends up taking a reference on the SCSI driver which ends up taking its own reference on the USB driver(s) involved), or a reference via a non-filesystem opbject. And on Linux, network interfaces aren't filesystem objects - there isn't a /dev/eth0 for your ethernet. That's why you have to use netlink to enumerate your interfaces. The *correct* short answer is, of course, "use trace-cmd or kernelshark to trace calls to module_get for the problem module". :)
participants (4)
-
Aruna Hewapathirane -
Kamil Konieczny -
Kevin Wilson -
valdis.kletnieks＠vt.edu