Re: [PATCH] uio: User IRQ Mode

From: "Magnus Damm" <magnus.damm@xxxxxxxxx>
Date: Thu, 3 Jul 2008 14:11:22 +0900

On Wed, Jul 2, 2008 at 8:31 PM, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

Note that the irq is disabled instead of acked. So this should not be a
problem. The userspace part then is responsible to ack (first) and
unmask the irq.

That still doesn't make sense.

If you call disable_irq in the IRQ handler you will deadlock because it
waits until the IRQ handler has completed.

Right, the uio_userirq_handler() function should use
disable_irq_nosync() instead of disable_irq(). Otherwise we'll end up
waiting forever for IRQ_INPROGRESS to be cleared in synchronize_irq()
in the case of CONFIG_SMP.

Thanks!

/ magnus
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References:
- [PATCH] uio: User IRQ Mode
  - From: Magnus Damm
- Re: [PATCH] uio: User IRQ Mode
  - From: Alan Cox
- Re: [PATCH] uio: User IRQ Mode
  - From: Uwe Kleine-König
- Re: [PATCH] uio: User IRQ Mode
  - From: Alan Cox

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