x86: revert irq number limitation

Impact: fix MSIx not enough irq numbers available regression

The manual revert of the sparse_irq patches missed to bring the number
of possible irqs back to the .27 status. This resulted in a regression
when two multichannel network cards were placed in a system with only
one IO_APIC - causing the networking driver to not have the right
IRQ and the device not coming up.

Remove the dynamic allocation logic leftovers and simply return
NR_IRQS in probe_nr_irqs() for now.

   Fixes: http://lkml.org/lkml/2008/11/19/354Reported-by: NJesper Dangaard Brouer <hawk@diku.dk>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NJesper Dangaard Brouer <hawk@diku.dk>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/io_apic.c

@@ -3608,27 +3608,7 @@ int __init io_apic_get_redir_entries (int ioapic)
 
 int __init probe_nr_irqs(void)
 {
-	int idx;
-	int nr = 0;
-#ifndef CONFIG_XEN
-	int nr_min = 32;
-#else
-	int nr_min = NR_IRQS;
-#endif
-
-	for (idx = 0; idx < nr_ioapics; idx++)
-		nr += io_apic_get_redir_entries(idx) + 1;
-
-	/* double it for hotplug and msi and nmi */
-	nr <<= 1;
-
-	/* something wrong ? */
-	if (nr < nr_min)
-		nr = nr_min;
-	if (WARN_ON(nr > NR_IRQS))
-		nr = NR_IRQS;
-
-	return nr;
+	return NR_IRQS;
 }
 
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