RHEL5: irqbalance does not honors IRQBALANCE_BANNED_INTERRUPTS clause

Issue

irqbalance touches a IRQ CPU mask, even if configured explicitly to not be managed.

If you have declared the following clauses at /etc/sysconfig/irqbalance:

IRQBALANCE_BANNED_INTERRUPTS="59"
IRQBALANCE_BANNED_CPUS="aaaa"

And start irqbalance. Immediately after starting irqbalance, define a custom CPU mask for that IRQ:

    # echo aaaa > /proc/irq/59/smp_affinity

After a minute, irqbalance rewrites irq59 CPU mask.