scsi: mpt3sas: Cancel the running work during host reset

It is not recommended to issue back-to-back host reset without any delay.
However, if someone issues back-to-back host reset then we observe that
target devices get unregistered and re-register with SML.  And if OS drive
is behind the HBA when it gets unregistered, then file-system goes into
read-only mode.

Normally during host reset, driver marks accessible target devices as
responding and triggers the event MPT3SAS_REMOVE_UNRESPONDING_DEVICES to
remove any non-responding devices through FW worker thread. While
processing this event, driver unregisters the non-responding devices and
clears the responding flag for all the devices.

Currently, during host reset, driver is cancelling only those Firmware
event works which are pending in Firmware event workqueue. It is not
cancelling work which is currently running. Change the driver to cancel all
events.

Link: https://lore.kernel.org/r/1596096229-3341-4-git-send-email-suganath-prabu.subramani@broadcom.comSigned-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.h

@@ -1036,6 +1036,8 @@ typedef void (*MPT3SAS_FLUSH_RUNNING_CMDS)(struct MPT3SAS_ADAPTER *ioc);
  * @firmware_event_thread: ""
  * @fw_event_lock:
  * @fw_event_list: list of fw events
+ * @current_evet: current processing firmware event
+ * @fw_event_cleanup: set to one while cleaning up the fw events
  * @aen_event_read_flag: event log was read
  * @broadcast_aen_busy: broadcast aen waiting to be serviced
  * @shost_recovery: host reset in progress
@@ -1217,6 +1219,8 @@ struct MPT3SAS_ADAPTER {
 	struct workqueue_struct	*firmware_event_thread;
 	spinlock_t	fw_event_lock;
 	struct list_head fw_event_list;
+	struct fw_event_work	*current_event;
+	u8		fw_events_cleanup;
 
 	 /* misc flags */
 	int		aen_event_read_flag;

drivers/scsi/mpt3sas/mpt3sas_scsih.c

@@ -3323,11 +3323,13 @@ _scsih_fw_event_cleanup_queue(struct MPT3SAS_ADAPTER *ioc)
 {
 	struct fw_event_work *fw_event;
 
-	if (list_empty(&ioc->fw_event_list) ||
+	if ((list_empty(&ioc->fw_event_list) && !ioc->current_event) ||
 	     !ioc->firmware_event_thread || in_interrupt())
 		return;
 
-	while ((fw_event = dequeue_next_fw_event(ioc))) {
+	ioc->fw_events_cleanup = 1;
+	while ((fw_event = dequeue_next_fw_event(ioc)) ||
+	     (fw_event = ioc->current_event)) {
 		/*
 		 * Wait on the fw_event to complete. If this returns 1, then
 		 * the event was never executed, and we need a put for the
@@ -3341,6 +3343,7 @@ _scsih_fw_event_cleanup_queue(struct MPT3SAS_ADAPTER *ioc)
 
 		fw_event_work_put(fw_event);
 	}
+	ioc->fw_events_cleanup = 0;
 }
 
 /**
@@ -9421,11 +9424,13 @@ mpt3sas_scsih_reset_done_handler(struct MPT3SAS_ADAPTER *ioc)
 static void
 _mpt3sas_fw_work(struct MPT3SAS_ADAPTER *ioc, struct fw_event_work *fw_event)
 {
+	ioc->current_event = fw_event;
 	_scsih_fw_event_del_from_list(ioc, fw_event);
 
 	/* the queue is being flushed so ignore this event */
 	if (ioc->remove_host || ioc->pci_error_recovery) {
 		fw_event_work_put(fw_event);
+		ioc->current_event = NULL;
 		return;
 	}
 
@@ -9439,10 +9444,10 @@ _mpt3sas_fw_work(struct MPT3SAS_ADAPTER *ioc, struct fw_event_work *fw_event)
 		while (scsi_host_in_recovery(ioc->shost) ||
 					 ioc->shost_recovery) {
 			/*
-			 * If we're unloading, bail. Otherwise, this can become
-			 * an infinite loop.
+			 * If we're unloading or cancelling the work, bail.
+			 * Otherwise, this can become an infinite loop.
 			 */
-			if (ioc->remove_host)
+			if (ioc->remove_host || ioc->fw_events_cleanup)
 				goto out;
 			ssleep(1);
 		}
@@ -9503,11 +9508,13 @@ _mpt3sas_fw_work(struct MPT3SAS_ADAPTER *ioc, struct fw_event_work *fw_event)
 		break;
 	case MPI2_EVENT_PCIE_TOPOLOGY_CHANGE_LIST:
 		_scsih_pcie_topology_change_event(ioc, fw_event);
+		ioc->current_event = NULL;
 			return;
 	break;
 	}
 out:
 	fw_event_work_put(fw_event);
+	ioc->current_event = NULL;
 }
 
 /**