linux-kernel - Re: network driver usage count

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Message-ID: <87myt7nt0k.fsf@szonett.ki.iif.hu>
Date:	Wed, 21 Nov 2007 23:16:59 +0100
From:	Wagner Ferenc <wferi@...f.hu>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: network driver usage count

Stephen Hemminger <shemminger@...ux-foundation.org> writes:

> On Wed, 21 Nov 2007 20:45:11 +0100
> Ferenc Wagner <wferi@...f.hu> wrote:
>
>> Under 2.6.23.1, my lsmod output shows this:
>> 
>> $ lsmod | grep tg3
>> tg3                   100580  0 
>> 
>> The usage count is zero, even though it drives my two physical
>> interfaces:
>> 
>> $ ls -l /sys/class/net/eth-gb?/device/driver
>> lrwxrwxrwx 1 root root 0 2007-11-21 19:58 /sys/class/net/eth-gb1/device/driver -> ../../../bus/pci/drivers/tg3
>> lrwxrwxrwx 1 root root 0 2007-11-21 19:58 /sys/class/net/eth-gb2/device/driver -> ../../../bus/pci/drivers/tg3
>> 
>> These interfaces are up and bonded together, but that doesn't seem to
>> matter at all.  I also checked other machines, the network driver
>> (tg3, e1000) usage counts are always zero under various recent 2.6
>> kernels, but nonzero under 2.4.21 for example.
>> 
>> And really, the module could be removed, cutting my ssh session. :)
>> 
>> Was this made possible intentionally?  If yes, why?
>
> Yes, so devices can be removed at anytime.

Hmm, that would warrant nuking all the reference counts on every
driver.  I must be missing something, since I really feel it goes
against common sense.  Can you point me to some discussion of this
change?  I mean, I couldn't remove the driver of a mounted filesystem.
So why can I remove a driver serving live network traffic?
-- 
Thanks,
Feri.
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