powerpc/pseries: Auto-online hotplugged memory

A recent update (commit id 31bc3858ea3) allows for automatically
onlining memory that is added. This patch sets the config option
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y for pseries and updates the
pseries memory hotplug code so that DLPAR added memory can be
automatically onlined instead of explicitly onlining the memory.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/pseries_defconfig

@@ -53,6 +53,7 @@ CONFIG_KEXEC=y
 CONFIG_IRQ_ALL_CPUS=y
 CONFIG_MEMORY_HOTPLUG=y
 CONFIG_MEMORY_HOTREMOVE=y
+CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
 CONFIG_KSM=y
 CONFIG_TRANSPARENT_HUGEPAGE=y
 CONFIG_PPC_64K_PAGES=y

arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -590,7 +590,6 @@ static int dlpar_memory_remove_by_index(u32 drc_index, struct property *prop)
 
 static int dlpar_add_lmb_memory(struct of_drconf_cell *lmb)
 {
-	struct memory_block *mem_block;
 	unsigned long block_sz;
 	int nid, rc;
 
@@ -611,19 +610,6 @@ static int dlpar_add_lmb_memory(struct of_drconf_cell *lmb)
 		return rc;
 	}
 
-	mem_block = lmb_to_memblock(lmb);
-	if (!mem_block) {
-		remove_memory(nid, lmb->base_addr, block_sz);
-		return -EINVAL;
-	}
-
-	rc = device_online(&mem_block->dev);
-	put_device(&mem_block->dev);
-	if (rc) {
-		remove_memory(nid, lmb->base_addr, block_sz);
-		return rc;
-	}
-
 	lmb->flags |= DRCONF_MEM_ASSIGNED;
 	return 0;
 }