Philippe Gerum via Xenomai authored Apr 24, 2019 and Jan Kiszka committed Apr 25, 2019

The implementation does not iterate fully over all CPU slots for every
handler, leaving some of them uncollected. In addition, if maxcpus= is
used to restrict the number of available CPUs to a subset of the
present ones, with the highest numbered CPU marked offline, the
iterator rescans the first valid IRQ slot indefinitely, eventually
leading to memory corruption due to out-of-bound writes.

Rewrite the iterator in order to implement the following loop as
expected:

for_each_irq(irq)
    for_each_handler_of_irq(handler, irq)
    	for_each_online_cpu(cpu)
	    collect_stats(irq, handler, cpu);

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>