Re: LiS ldl driver with 2.6 kernels

> > 1) Calling sap_create() under lock. The problem is that sap_create()
> > might invoke dev_add_pack() that can sleep, since kernel 2.5.70. I
> > choose to remove the call to dev_add_pack() from sap_create() and make

> dev_add_pack does not sleep.

I mixed up the reason for the change, because I've done several
changes at once. I still think the patch is right. dev_add_pack()
definitly does not sleep, but still, it cannot be called with IRQs
disabled, the reason is the following : dev_add_pack() uses bh-safe
spinlocks, spin_unlock_bh() in turn uses local_bh_enable() which
complains loudly when IRQs are disabled (At least in miy 2.6.7
kernel). And in ldl drivers IRQs are disabled after SPLSTR is done,
because LiS uses irq-safe spinlocks for it. So I still think that my
fixes for dev_add_pack apply.



> > 4) Doing spin_unlock_bh() while holding irq-disabling lock. I choose
> > to change the locking to be irq-safe, that does not have that problem.
> > Due to my limited understaing of Linux kernel locking rules, I'm not
> > completely sure it is correct. I thing that disabling local irqs
> > guarantees that no bh processing is done, but I might be wrong.

> irq locking is too severe.

I'm well aware of that. Still, the change to use IRQ safe locking is
donw for the same reason as the previous change. spin_unlock_bh()
complains when called with IRQs disabled. But the actual performance
hit of converting to spinlock_irqsafe will be minimal, because SPLSTR
had already disabled IRQs by the time we'd want to lock.

-- 
Zaar