Re: IDE locking problem

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> It only works with default/legacy io bases.

Which is all I care about in this specific situation. The "mediabay"
hotswap controller is driven by ide-pmac, which provides it's own
ide_init_hwif_ports() and ide_default_io_base() arch hooks. (In the
PPC arch, those arch functions can be themselves hooked in by the
actual platform code, on pmac, this goes to ide-pmac, though I also
deal with added PCI cards).

> > Also, look at my patch, we also _NEED_ to add some proper
> > device_unregister calls to ide_unregister() or this function will
> > leave dangling entries in the device list, and since those have the
> > same restrictions as the new blk_cleanup_queue(), we really need to
> > do that without the lock held.
> 
> Yes.

That reminds me that without this fix, even ide-cs will break things
when ejecting a CF card for example.

> > I'd suggest merging my patch for now, it won't make things much
> > worse than what they are today regarding racyness of IDE registration
> > and unregistration, we an look into sanitizing this as a 2.7 goal.
> 
> Okay :\.

Heh, thanks... Well... who else uses ide_unregister except ide-pmac and
ide-cs anyway ? If it's really that little used, it's quite under control
and we can try to clean it up a bit more then during early 2.6.0...

Right now, I'm waiting to see what we can come up to with Jens Axboe
regarding race-free teardown of the blk queue. Once that's agreed, we
can think about just removing the call to init_hwif_data and just reinit
the drive array ourselves. That would be a good thing anyway as the
current ide_unregister allocation of a full hwif_t on stack is causing
other problems (stack bloat typically, an issue with people trying to
shrink the kernel process stack to 1 page).

Ben.