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From: David Brownell <david-b@pacbell.net>
To: linux-hotplug@vger.kernel.org
Subject: Re: unloading drivers and usage counters
Date: Mon, 22 Jan 2001 05:28:41 +0000	[thread overview]
Message-ID: <marc-linux-hotplug-98014110830019@msgid-missing> (raw)
In-Reply-To: <marc-linux-hotplug-98011145918383@msgid-missing>

> From: Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>
> Sent: Sunday, January 21, 2001 1:12 PM
> 
> going through the hotplugging scripts I noticed that there's no good way to 
> unload modules. A time based approach cannot be used due to race conditions.

No good way now, true; I'm not sure I'd call the reasons "races" though.
More like different models for why "kernel modules" get used.


> Unloading on device removal requires keeping a usage counter in user space.
> This seems to be a brittle approach.

I can imagine implementing a workable solution in userspace,
which may be the best that the 2.4 kernels can handle.  Yep,
brittle is a good word for that!


> Not increasing the module usage counters on connect seems to be the wrong 
> strategy.  The desire to keep the modules unloadable has come back to bite us
> into our behind.
> If the usage counters were increased for each connected device unloading would
> come natural.

Sounds like a substantial change in the model for what module use
counts should be.  Maybe the pcmcia_cs tools have a better model?

- Dave


>     A patch to disconnect drivers by an ioctl has been posted. It 
> would allow forced unload.





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  reply	other threads:[~2001-01-22  5:28 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-01-21 21:12 unloading drivers and usage counters Oliver Neukum
2001-01-22  5:28 ` David Brownell [this message]
2001-01-22  6:04 ` David Hinds
2001-01-22 16:26 ` David Brownell

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