scsi: mpt3sas: Fix Sync cache command failure during driver unload

This is to fix SYNC CACHE and START STOP command failures with
DID_NO_CONNECT during driver unload.

In driver's IO submission patch (i.e. in driver's .queuecommand()) driver
won't allow any SCSI commands to the IOC when ioc->remove_host flag is set
and hence SYNC CACHE commands which are issued to the target drives (where
write cache is enabled) during driver unload time is failed with
DID_NO_CONNECT status.

Now modified the driver to allow SYNC CACHE and START STOP commands to IOC,
even when remove_host flag is set.
Signed-off-by: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_scsih.c

@@ -3748,6 +3748,40 @@ _scsih_tm_tr_complete(struct MPT3SAS_ADAPTER *ioc, u16 smid, u8 msix_index,
 	return _scsih_check_for_pending_tm(ioc, smid);
 }
 
+/** _scsih_allow_scmd_to_device - check whether scmd needs to
+ *				 issue to IOC or not.
+ * @ioc: per adapter object
+ * @scmd: pointer to scsi command object
+ *
+ * Returns true if scmd can be issued to IOC otherwise returns false.
+ */
+inline bool _scsih_allow_scmd_to_device(struct MPT3SAS_ADAPTER *ioc,
+	struct scsi_cmnd *scmd)
+{
+
+	if (ioc->pci_error_recovery)
+		return false;
+
+	if (ioc->hba_mpi_version_belonged == MPI2_VERSION) {
+		if (ioc->remove_host)
+			return false;
+
+		return true;
+	}
+
+	if (ioc->remove_host) {
+
+		switch (scmd->cmnd[0]) {
+		case SYNCHRONIZE_CACHE:
+		case START_STOP:
+			return true;
+		default:
+			return false;
+		}
+	}
+
+	return true;
+}
 
 /**
  * _scsih_sas_control_complete - completion routine
@@ -4571,7 +4605,7 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 		return 0;
 	}
 
-	if (ioc->pci_error_recovery || ioc->remove_host) {
+	if (!(_scsih_allow_scmd_to_device(ioc, scmd))) {
 		scmd->result = DID_NO_CONNECT << 16;
 		scmd->scsi_done(scmd);
 		return 0;