ACPI: avoid irqrouter_resume might_sleep oops on resume from S4

__might_sleep+0x8e/0x93
acpi_os_wait_semaphore+0x50/0xa3
acpi_ut_acquire_mutex+0x28/0x6a
acpi_ns_get_node+0x46/0x88
acpi_ns_evaluate+0x2d/0xfc
acpi_rs_set_srs_method_data+0xc5/0xe1
acpi_set_current_resources+0x31/0x3f
acpi_pci_link_set+0xfc/0x1a5
irqrouter_resume+0x48/0x5f

and

__might_sleep+0x8e/0x93
kmem_cache_alloc+0x2a/0x8f
acpi_evaluate_integer+0x32/0x96
acpi_bus_get_status+0x30/0x84
acpi_pci_link_set+0x12a/0x1a5
irqrouter_resume+0x48/0x5f

http://bugzilla.kernel.org/show_bug.cgi?id=6810

Signed-off-by: Len Brown <[e-mail]>

drivers/acpi/osl.c

···
 	ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "Waiting for semaphore[%p|%d|%d]\n",
 			  handle, units, timeout));
 
+	/*
+	 * This can be called during resume with interrupts off.
+	 * Like boot-time, we should be single threaded and will
+	 * always get the lock if we try -- timeout or not.
+	 * If this doesn't succeed, then we will oops courtesy of
+	 * might_sleep() in down().
+	 */
+	if (!down_trylock(sem))
+		return AE_OK;
+
 	switch (timeout) {
 		/*
 		 * No Wait:

drivers/acpi/utils.c

···
 	if (!data)
 		return AE_BAD_PARAMETER;
 
-	element = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
+	element = kmalloc(sizeof(union acpi_object), irqs_disabled() ? GFP_ATOMIC: GFP_KERNEL);
 	if (!element)
 		return AE_NO_MEMORY;