Re: [PATCH] PPC64 iSeries: don't share request queues in viocd

From: Nick Piggin
Date: Mon Nov 15 2004 - 06:45:52 EST


Christoph Hellwig wrote:
On Mon, Nov 15, 2004 at 04:53:57PM +1100, Stephen Rothwell wrote:

Hi Andrew,

This patch fixes the virtual cdrom driver to not share a single request
queue. Sharing the queue causes an oops if you remove the module and more
than one cdrom exists.


Maybe you should fix that underlying bug? Queues are supposed to be
shareable.


I think shared queues are actually quite fundamentally broken at the
moment (as pointed out to me by Al). It stems from the refcounting /
conceptual relationship between a gendisk and a queue (I think - been
a while since I looked at the code).

I had something which just about fixed it up except that I couldn't
work out an appropriate place and name for the "queue" in the sysfs
hierarcy (IIRC I just had it as a sequentially increasing number, in
/sys/block/).

It is a relationship that I don't think sysfs can capture very well:
queues are shared between multiple other objects, but they have no
meaning outside the context of one of these objects.
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