[SCSI] mpt2sas: Fix for deadlock between hot plug worker threads and host reset context

This is due to driver reporting a device missing to the OS then the OS sending
a SYNC_CACHE request to driver while the IO queues are locked due to host reset.

To fix the issue, the driver will be waking up the port enable context
immediately when the driver receives the reply message, instead of waiting
on the hot plug worker threads.

Signed-off-by: Nagalakshmi Nandigama <nagalakshmi.nandigama@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/mpt2sas/mpt2sas_scsih.c b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
index f9ce3195..1f28988 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_scsih.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
@@ -3059,6 +3059,7 @@
 		"handle(0x%04x), sas_addr(0x%016llx)\n", ioc->name, handle,
 			(unsigned long long)sas_address));
 		_scsih_ublock_io_device(ioc, handle);
+		sas_target_priv_data->handle = MPT2SAS_INVALID_DEVICE_HANDLE;
 	}
 
 	smid = mpt2sas_base_get_smid_hpr(ioc, ioc->tm_tr_cb_idx);
@@ -5201,6 +5202,9 @@
 	if (sas_device_backup.starget && sas_device_backup.starget->hostdata) {
 		sas_target_priv_data = sas_device_backup.starget->hostdata;
 		sas_target_priv_data->deleted = 1;
+		_scsih_ublock_io_device(ioc, sas_device_backup.handle);
+		sas_target_priv_data->handle =
+		     MPT2SAS_INVALID_DEVICE_HANDLE;
 	}
 
 	_scsih_ublock_io_device(ioc, sas_device_backup.handle);
@@ -5354,7 +5358,7 @@
 		_scsih_sas_topology_change_event_debug(ioc, event_data);
 #endif
 
-	if (ioc->shost_recovery || ioc->remove_host || ioc->pci_error_recovery)
+	if (ioc->remove_host || ioc->pci_error_recovery)
 		return;
 
 	if (!ioc->sas_hba.num_phys)
@@ -5415,6 +5419,9 @@
 		switch (reason_code) {
 		case MPI2_EVENT_SAS_TOPO_RC_PHY_CHANGED:
 
+			if (ioc->shost_recovery)
+				break;
+
 			if (link_rate == prev_link_rate)
 				break;
 
@@ -5428,6 +5435,9 @@
 			break;
 		case MPI2_EVENT_SAS_TOPO_RC_TARG_ADDED:
 
+			if (ioc->shost_recovery)
+				break;
+
 			mpt2sas_transport_update_links(ioc, sas_address,
 			    handle, phy_number, link_rate);
 
@@ -7091,7 +7101,13 @@
 		_scsih_search_responding_sas_devices(ioc);
 		_scsih_search_responding_raid_devices(ioc);
 		_scsih_search_responding_expanders(ioc);
+		if (!ioc->is_driver_loading) {
+			_scsih_prep_device_scan(ioc);
+			_scsih_search_responding_sas_devices(ioc);
+			_scsih_search_responding_raid_devices(ioc);
+			_scsih_search_responding_expanders(ioc);
 			_scsih_error_recovery_delete_devices(ioc);
+		}
 		break;
 	}
 }
@@ -7126,17 +7142,7 @@
 		_scsih_scan_for_devices_after_reset(ioc);
 		break;
 	case MPT2SAS_PORT_ENABLE_COMPLETE:
-		if (!ioc->is_driver_loading && ioc->shost_recovery) {
-			_scsih_prep_device_scan(ioc);
-			_scsih_search_responding_sas_devices(ioc);
-			_scsih_search_responding_raid_devices(ioc);
-			_scsih_search_responding_expanders(ioc);
-		}
-
-		if (ioc->start_scan)
-			ioc->start_scan = 0;
-		else
-			complete(&ioc->port_enable_done);
+		ioc->start_scan = 0;