On 15-Nov-2002 Randy.Dunlap wrote:
> On Thu, 14 Nov 2002, Duncan Haldane wrote:
>|
>| any ideas?
>
> Hi,
>
> I think that the usb_bus_list_lock semaphore just isn't
> initialized yet.
> This can happen because we don't have much control over
> the order of initcalls in 2.4. There is more control
> over them in 2.5.
>
> So I think that the usb_cpia_init() is happening before usb_init().
Yes, I think you are right.
To test your idea, I moved the initialization
init_MUTEX(&usb_bus_list_lock);
from usb_init() to just before the call to usb_scan_devices()
in usb_register() and the oops went away and cpia worked.
I see that in the working code prior to 2.4.13, usb_init() doesnt handle
any usb_bus_list_lock initialization. Hmmm.
I believe that cpia_usb.c cannot be compiled into the kernel unless
usb is also compiled into the kernel. Is there any way to move the
initialization of cpia_usb to later in the boot sequence?
Or put some #ifndef module ... #endif code that moves the lock initialization
to before the call to usb_scan devices, and tests whether it is done
so it is only initialized the first time usb_register is called?
Duncan
> One thing that we could do is have usb_register() return an
> error code in this case, but that probably wouldn't help in
> the long term. If it were a module, the module could be
> reloaded, but in this case, it's built-into-kernel, so it
> would just be dead.
>
> Another thing that we could do is try to do some init inside
> usb_register(), but that looks unsafe (racy).
>
> Another thing that we might do is try to force (control) the
> init order. This might be the best fix overall.
>
> Other ideas out there?
>
> --
> ~Randy
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E-Mail: Duncan Haldane <[EMAIL PROTECTED]>
Date: 15-Nov-2002
Time: 03:16:47
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