Subject: Re: linux-next: User Mode Linux broken

From: Thomas Gleixner <[email-masked]>
Date: Thu, 21 Oct 2010 18:09:22 +0200 (CEST)

On Thu, 21 Oct 2010, Richard Weinberger wrote:

> Thomas,
> 
> Your commit c5f7563 ("genirq: Provide compat handling for chip->enable()") 
> breaks UML.
> It does not start anymore.
> 
> When I apply this patch it works fine again.
> http://userweb.kernel.org/~akpm/mmotm/broken-out/um-migrate-from-__do_irq-to-
> generic_handle_irq.patch
> 
> Maybe your patch breaks all users of __do_IRQ()?

Not intentionally :)

The irq_chip of um has it's own dummy enable function, so the compat
code uses it.

+static void compat_irq_enable(struct irq_data *data)
+{
+	data->chip->enable(data->irq);
+}
+

...

+	if (chip->enable)
+		chip->irq_enable = compat_irq_enable;
+
+	/*
+	 * The real defaults
+	 */
+	if (!chip->irq_enable)
+		chip->irq_enable = default_enable;

So I really can't see how's that supposed to break UM

Thanks,

	tglx