BUG_ON(ev >= DISC_NUM_EVENTS);
 
        sas_queue_event(ev, &disc->disc_event_lock, &disc->pending,
-                       &disc->disc_work[ev].work, port->ha->core.shost);
+                       &disc->disc_work[ev].work, port->ha);
 
        return 0;
 }
 
        BUG_ON(event >= HA_NUM_EVENTS);
 
        sas_queue_event(event, &sas_ha->event_lock, &sas_ha->pending,
-                       &sas_ha->ha_events[event].work, sas_ha->core.shost);
+                       &sas_ha->ha_events[event].work, sas_ha);
 }
 
 static void notify_port_event(struct asd_sas_phy *phy, enum port_event event)
        BUG_ON(event >= PORT_NUM_EVENTS);
 
        sas_queue_event(event, &ha->event_lock, &phy->port_events_pending,
-                       &phy->port_events[event].work, ha->core.shost);
+                       &phy->port_events[event].work, ha);
 }
 
 static void notify_phy_event(struct asd_sas_phy *phy, enum phy_event event)
        BUG_ON(event >= PHY_NUM_EVENTS);
 
        sas_queue_event(event, &ha->event_lock, &phy->phy_events_pending,
-                       &phy->phy_events[event].work, ha->core.shost);
+                       &phy->phy_events[event].work, ha);
 }
 
 int sas_init_events(struct sas_ha_struct *sas_ha)
 
        else if (sas_ha->lldd_queue_size == -1)
                sas_ha->lldd_queue_size = 128; /* Sanity */
 
+       sas_ha->state = SAS_HA_REGISTERED;
+       spin_lock_init(&sas_ha->state_lock);
+
        error = sas_register_phys(sas_ha);
        if (error) {
                printk(KERN_NOTICE "couldn't register sas phys:%d\n", error);
 
 int sas_unregister_ha(struct sas_ha_struct *sas_ha)
 {
+       unsigned long flags;
+
+       /* Set the state to unregistered to avoid further
+        * events to be queued */
+       spin_lock_irqsave(&sas_ha->state_lock, flags);
+       sas_ha->state = SAS_HA_UNREGISTERED;
+       spin_unlock_irqrestore(&sas_ha->state_lock, flags);
+       scsi_flush_work(sas_ha->core.shost);
+
        sas_unregister_ports(sas_ha);
 
        if (sas_ha->lldd_max_execute_num > 1) {
 
 static inline void sas_queue_event(int event, spinlock_t *lock,
                                   unsigned long *pending,
                                   struct work_struct *work,
-                                  struct Scsi_Host *shost)
+                                  struct sas_ha_struct *sas_ha)
 {
        unsigned long flags;
 
        }
        __set_bit(event, pending);
        spin_unlock_irqrestore(lock, flags);
-       scsi_queue_work(shost, work);
+
+       spin_lock_irqsave(&sas_ha->state_lock, flags);
+       if (sas_ha->state != SAS_HA_UNREGISTERED) {
+               scsi_queue_work(sas_ha->core.shost, work);
+       }
+       spin_unlock_irqrestore(&sas_ha->state_lock, flags);
 }
 
 static inline void sas_begin_event(int event, spinlock_t *lock,
 
        struct sas_ha_struct *ha;
 };
 
+enum sas_ha_state {
+       SAS_HA_REGISTERED,
+       SAS_HA_UNREGISTERED
+};
+
 struct sas_ha_struct {
 /* private: */
        spinlock_t       event_lock;
        struct sas_ha_event ha_events[HA_NUM_EVENTS];
        unsigned long    pending;
 
+       enum sas_ha_state state;
+       spinlock_t        state_lock;
+
        struct scsi_core core;
 
 /* public: */