Messages in this thread | | | Date | Thu, 10 Jul 2008 12:47:49 +0200 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] uio: uio_pdrv_genirq V2 |
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Hello Alan,
Alan Cox wrote: > On Thu, 10 Jul 2008 12:30:36 +0200 > Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com> wrote: > > > Alan Cox wrote: > > > > > > > > + else if (!irq_on && !priv->irq_disabled) > > > > > + disable_irq(dev_info->irq); > > > > I'm not sure if this is a problem on SMP. Should you use > > > > disable_irq_nosync here, too? Probably it's OK. > > > > > > That one will also deadlock. > > Can you explain why? I think irqcontrol is only called in task context. > > I only see one possible deadlock and that's disable_irq being called > > while the irq is IRQ_INPROGRESS on the same cpu. I'm always willing to > > learn. > > CPU0 (UIO IRQ) CPU1 (irqcontrol) > take IRQ > take spin lock > spin on spinlock > disable_irq (blocks) Ah, OK, that's because uio_pdrv_genirq_handler and uio_pdrv_genirq_irqcontrol share the lock.
Is this something that lockdep can detect?
Best regards and thanks for clearifying Uwe
-- Uwe Kleine-König, Software Engineer Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962 -- 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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