linux modules

nasarlinux · 09-13-2005, 06:30 AM

Hi,

lsmod gives me a "Used by" column which is a count. It represents the usage count of the module. Can anybody tell me how to find out which process uses this. I want unload a module like yenta_socket, but i could not do it becuase some process uses it and i could not get which process using this module.

thanks
Nasar

JCipriani · 09-13-2005, 11:16 PM

If it's yenta_socket, it's probably some program that's using a PCMCIA device.

If the module you are trying to unload is a device driver module, first do

Code:

cat /proc/devices

You'll see a list of module names and associated device numbers, for example:

Code:

Character devices:
  1 mem
  2 pty
  3 ttyp
  4 ttyS
  5 cua
  7 vcs
 10 misc
 13 input
 14 sound
 21 sg
 29 fb
 36 netlink

Then you can look in /dev and see which devices have that major number; in that pair of numbers just before the data, the first one is the major number. For example:

Code:

$ ls -la /dev | grep " 14,"
crw-------    1 root     root      14,   4 Aug 30  2002 audio
crw-------    1 root     root      14,  20 Aug 30  2002 audio1
crw-------    1 root     root      14,   7 Aug 30  2002 audioctl
crw-------    1 root     root      14,   3 Aug 30  2002 dsp
crw-------    1 root     root      14,  19 Aug 30  2002 dsp1
crw-------    1 root     root      14,   2 Aug 30  2002 midi00
crw-------    1 root     root      14,  18 Aug 30  2002 midi01
crw-------    1 root     root      14,  34 Aug 30  2002 midi02
crw-------    1 root     root      14,  50 Aug 30  2002 midi03
crw-------    1 root     root      14,   0 Aug 30  2002 mixer
crw-------    1 root     root      14,  16 Aug 30  2002 mixer1
crw-------    1 root     root      14,  17 Aug 30  2002 patmgr0
crw-------    1 root     root      14,  33 Aug 30  2002 patmgr1
crw-------    1 root     root      14,   1 Aug 30  2002 sequencer
crw-------    1 root     root      14,   8 Aug 30  2002 sequencer2
crw-------    1 root     root      14,   6 Aug 30  2002 sndstat

And that might give you a hint as to which program it is. I know there's a way to list all open files by all processes, and I'll be damned if I can remember what it is. You could use that to see which processes have the device in question open.

It's also possible that another module caused your module to load, indirectly. In that case, that other module will be listed in the "used by" column in lsmod, and you can look for that module instead.

There's probably a better way to do all of this, too. But I don't know it, although I'd like to. You could probably poke around in /proc/*/fd and write a script or use find or something to figure out which process has the device open. That's all assuming it's a device driver module that's actually associated with some device that a process is using, of course.

Sorry, that's the best I could come up with.

Jason

JCipriani · 09-13-2005, 11:23 PM

The command to list open files is lsof, which might be in /sbin or /usr/sbin. The man page is big but it does exist.

Oh, and, it's also possible, if the module itself is buggy or if something went wrong, that a process stopped using it but it's usage count wasn't decremented. In that case there's nothing you can do about it... but that's probably not the case at all. But it can happen.

nasarlinux · 09-14-2005, 08:04 AM

Hi,

Thanks you very much.

I'll see the man page of lsof.

--Nasar