[Jaunty] [Karmic] Fix hostap interrupt handler oops on bootup

[Colin Ian King]

https://bugs.launchpad.net/ubuntu/+bug/254837

SRU Justification:

Impact: Booting with the Senao NL-2511CD (PRISM II compatible) wireless
card can generate a kernel oops in the hostap interrupt handler.

Spurious shared interrupts or early probing interrupts can cause the
hostap interrupt handler to oops before the driver has fully configured
the IO base port addresses. In some cases the oops can be because
the hardware shares an interrupt line, on other cases it is due to a
race condition between probing for the hardware and configuring
the IO base port. The latter occurs because the probing is required to
determine the hardware port address which is only determined when the
probe can interrupt the hardware (catch 22).

Fix: This patch catches this pre-configured condition in the interrupt
handler to avoid the oops.

Testcase: Without the patch a kernel oops occurs on boot when the card
is installed. With the patch, there is no kernel oops and the wireless
card works.

I originally started debugging this with a user on a Jaunty kernel, and
now they have moved to Karmic. This patch will has been tested on Karmic
by Dan Taylor Jr. and the patch will fix the problem for Jaunty too,
c.f. https://bugs.launchpad.net/ubuntu/+bug/254837/comments/56

Attached: The patch.

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