[PATCH 1/2] powerpc/pseries: Introduce memory hotplug READD operation

[John Allen]

Currently, memory must be hot removed and subsequently re-added in order
to dynamically update the affinity of LMBs specified by a PRRN event.
Earlier implementations of the PRRN event handler ran into issues in which
the hot remove would occur successfully, but a hotplug event would be
initiated from another source and grab the hotplug lock preventing the hot
add from occurring. To prevent this situation, this patch introduces the
notion of a hot "readd" action for memory which atomizes a hot remove and
a hot add into a single, serialized operation on the hotplug queue.

Signed-off-by: John Allen <jallen at linux.vnet.ibm.com>
---
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 9c23baa..076b892 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -318,6 +318,7 @@ struct pseries_hp_errorlog {

 #define PSERIES_HP_ELOG_ACTION_ADD	1
 #define PSERIES_HP_ELOG_ACTION_REMOVE	2
+#define PSERIES_HP_ELOG_ACTION_READD	3

 #define PSERIES_HP_ELOG_ID_DRC_NAME	1
 #define PSERIES_HP_ELOG_ID_DRC_INDEX	2
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 76ec104..291d49b 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -766,6 +766,11 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
 		else
 			rc = -EINVAL;
 		break;
+	case PSERIES_HP_ELOG_ACTION_READD:
+		rc = dlpar_memory_remove_by_index(drc_index, prop);
+		if (!rc)
+			dlpar_memory_add_by_index(drc_index, prop);
+		break;
 	default:
 		pr_err("Invalid action (%d) specified\n", hp_elog->action);
 		rc = -EINVAL;