[SCSI] megaraid_sas: Fix synchronization problem between sysPD IO path and AEN path

There is syncronization problem between sysPD IO path and AEN path. Driver
maintains instance->pd_list[] array, which will get updated(by calling
function megasas_get_pd_list[]), whenever any of below events occurs-

MR_EVT_PD_INSERTED
MR_EVT_PD_REMOVED
MR_EVT_CTRL_HOST_BUS_SCAN_REQUESTED
MR_EVT_FOREIGN_CFG_IMPORTED

At same time running sysPD IO will be accessing the same array
instance->pd_list[], which is getting updated in AEN path, because of this IO
may not get correct PD info from instance->pd_list[] array.
Signed-off-by: NAdam Radford <adam.radford@lsi.com>
Signed-off-by: NSumit Saxena <sumit.saxena@lsi.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/megaraid/megaraid_sas.h

@@ -1531,6 +1531,7 @@ struct megasas_instance {
 	struct megasas_register_set __iomem *reg_set;
 	u32 *reply_post_host_index_addr[MR_MAX_MSIX_REG_ARRAY];
 	struct megasas_pd_list          pd_list[MEGASAS_MAX_PD];
+	struct megasas_pd_list          local_pd_list[MEGASAS_MAX_PD];
 	u8     ld_ids[MEGASAS_MAX_LD_IDS];
 	s8 init_id;
 

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -3194,19 +3194,21 @@ megasas_get_pd_list(struct megasas_instance *instance)
 	     (le32_to_cpu(ci->count) <
 		  (MEGASAS_MAX_PD_CHANNELS * MEGASAS_MAX_DEV_PER_CHANNEL))) {
 
-		memset(instance->pd_list, 0,
+		memset(instance->local_pd_list, 0,
 			MEGASAS_MAX_PD * sizeof(struct megasas_pd_list));
 
 		for (pd_index = 0; pd_index < le32_to_cpu(ci->count); pd_index++) {
 
-			instance->pd_list[le16_to_cpu(pd_addr->deviceId)].tid	=
+			instance->local_pd_list[le16_to_cpu(pd_addr->deviceId)].tid	=
 				le16_to_cpu(pd_addr->deviceId);
-			instance->pd_list[le16_to_cpu(pd_addr->deviceId)].driveType	=
+			instance->local_pd_list[le16_to_cpu(pd_addr->deviceId)].driveType	=
 							pd_addr->scsiDevType;
-			instance->pd_list[le16_to_cpu(pd_addr->deviceId)].driveState	=
+			instance->local_pd_list[le16_to_cpu(pd_addr->deviceId)].driveState	=
 							MR_PD_STATE_SYSTEM;
 			pd_addr++;
 		}
+		memcpy(instance->pd_list, instance->local_pd_list,
+			sizeof(instance->pd_list));
 	}
 
 	pci_free_consistent(instance->pdev,