Re: Patch for usb-storage in 2.4 [linux-usb-devel]

[Pete Zaitcev <zaitcev@redhat.com>]

On Sat, 10 Apr 2004 17:09:57 -0700
Matthew Dharm <mdharm-kernel@one-eyed-alien.net> wrote:

> I'm uncertain if your handling of the io_request_lock is right.... but
> getting information on how to handle that has been like pulling teeth, so
> I'm inclined to trust your wide-scale testing on this.

It's not wide-scale, unfortunately, that's why I need more review and
testing of it. Those "Enterprise" people are mostly interested in very
specific things, in particular Bladecenter and JS-20, Dell's OEMed CD-ROMs,
and Lexar memory key which Dell resells. Very likely not all transports
or protocols are tested, for instance UFI. But I think it's right to
call it "intensive" testing.

The main test is to put a CD and keyboard on a hub, and hub on a KVM, then
flip KVM several times quickly from one blade to another. All hell breaks
loose. IIRC, I had four different OOPS and lockup scenarios.

> Was there a reason to add more do-nothing code to host_reset?

Woopsie. I wanted to write it, but understood that if I return right
code from "bus" reset, it should never be called. Sorry about that...
I'll remove that part.

> Is it really safe to remove the irq_urb_sem?

The idea here is to have disconnect and resets locked against each other.
They happen on different threads, unfortunately (khubd and scsi_eh).
Initially I tried various orders, but then I thought, "Why am I making
it hard on myself?! Much better just to merge them". The dev_semaphore now
covers everything irq_urb_sem used to cover, except one path into
usb_stor_allocate_irq from initial probing.

Thanks for looking at it!

-- Pete