Messages in this thread | | | Date | Wed, 31 May 2006 08:31:03 +0200 | From | Ingo Molnar <> | Subject | Re: 2.6.17-rc5-mm1 |
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* Andrew Morton <akpm@osdl.org> wrote:
> Without having looked at it very hard, I'd venture that this is a > false positive - that driver uses disable_irq() to prevent reentry > onto that lock.
correct.
> It does that because it knows it's about to spend a long time talking > with the mii registers and it doesn't want to do that with interrupts > disabled.
i still consider it a 'quirky' locking construct, because disabling interrupts for a long time also disables all other devices sharing the same IRQ line - not nice.
Also, this is a really hard case for lockdep to detect automatically. (fortunately it's also relatively rare)
OTOH, the straightforward lockdep workaround would be to take the spinlock and thus disable all local interrupts - not too nice either.
Albeit in some ways it's still a bit nicer conceptually than disabling the irq line, because other CPUs are still operational, and under certain locking designs [preempt-rt] spin_lock_irq() does not disable local interrupts.
Steve, can you think of any better solution? I dont have this card.
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