[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>

drivers/scsi/mpt2sas/mpt2sas_scsih.c

@@ -3059,6 +3059,7 @@ _scsih_tm_tr_send(struct MPT2SAS_ADAPTER *ioc, u16 handle)
 		"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 @@ _scsih_remove_device(struct MPT2SAS_ADAPTER *ioc,
 	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(struct MPT2SAS_ADAPTER *ioc,
 		_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 @@ _scsih_sas_topology_change_event(struct MPT2SAS_ADAPTER *ioc,
 		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 @@ _scsih_sas_topology_change_event(struct MPT2SAS_ADAPTER *ioc,
 			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 @@ mpt2sas_scsih_reset_handler(struct MPT2SAS_ADAPTER *ioc, int reset_phase)
 		_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 @@ _firmware_event_work(struct work_struct *work)
 		_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;