x86, ioapic: Fix potential resume deadlock

Fix a potential deadlock when resuming; here the calling
function has disabled interrupts, so we cannot sleep.

Change the memory allocation flag from GFP_KERNEL to GFP_ATOMIC.

TODO: We can do away with this memory allocation during resume
      by reusing the ioapic suspend/resume code that uses boot time
      allocated buffers, but we want to keep this -stable patch
      simple.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org> # v2.6.38/39
Link: http://lkml.kernel.org/r/20110518233157.385970138@sbsiddha-MOBL3.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/apic/io_apic.c

@@ -621,14 +621,14 @@ struct IO_APIC_route_entry **alloc_ioapic_entries(void)
 	struct IO_APIC_route_entry **ioapic_entries;
 
 	ioapic_entries = kzalloc(sizeof(*ioapic_entries) * nr_ioapics,
-				GFP_KERNEL);
+				GFP_ATOMIC);
 	if (!ioapic_entries)
 		return 0;
 
 	for (apic = 0; apic < nr_ioapics; apic++) {
 		ioapic_entries[apic] =
 			kzalloc(sizeof(struct IO_APIC_route_entry) *
-				nr_ioapic_registers[apic], GFP_KERNEL);
+				nr_ioapic_registers[apic], GFP_ATOMIC);
 		if (!ioapic_entries[apic])
 			goto nomem;
 	}