Re: [PATCH] uio: uio_pdrv_genirq V2

[Alan Cox]

> > +       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.

The easiest fix is probably to use test_and_set and friends for each I/O
operation. You would then not need the lock to protect ->irq_disabled.
Propogating that throughout means your user space has to handle the case
of an IRQ arriving after disable returns but would be a fair bit saner I
think ?
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