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On Wed, 2006-05-31 at 08:31 +0200, Ingo Molnar wrote: > * 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) What's the standard way to teach lockdep about this? > > 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. Until this popped up, I didn't know I had this card either ;) (the last time we dealt with this card was to help someone else) Anyway, I'll look into the way this card works and start to play with it when I get some time. Andrew, do you have any docs that I can read to understand the card a little better? Thanks, -- Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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