Re: [PATCH] PHYLIB: IRQ event workqueue handling fixes

Maciej W. Rozycki
2007-10-19T12:57:59Z

On Fri, 19 Oct 2007, Jarek Poplawski wrote:

> 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