On Fri, 19 Oct 2007, Jarek Poplawski wrote:

quoted text
> But then... your patch seems to make it possible, because it enables
> irq to the initial state of the counter. Of course, this could happen
> on closing only.

 That's because free_irq() does not disable the interrupt in the correct 
manner.  The scenario is more or less like this:

phy_interrupt()				[depth == 0]
	disable_irq()
		depth++; status |= IRQ_DISABLED;
...
free_irq()				[depth == 1]
	status |= IRQ_DISABLED;
...
phy_change()				[depth == 1]
	enable_irq()
		depth--; status &= ~IRQ_DISABLED;
		oops!

Now if free_irq() correctly incremented the depth counter, then the last
enable_irq() would still decrement it, but with its initial value of 2 it 
would not change the status to reenable the line.

  Maciej
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