[SCSI] zfcp: Allow running unit/LUN shutdown without acquiring reference
Christof Schmitt [Wed, 8 Sep 2010 12:39:54 +0000 (14:39 +0200)]
With the change for the LUN data to be part of the scsi_device, the
slave_destroy callback will be the final call to the
zfcp_erp_unit_shutdown function. The erp tries to acquire a reference
to run the action asynchronously and fail, if it cannot get the
reference. But calling scsi_device_get from slave_destroy will fail,
because the scsi_device is already in the state SDEV_DEL.

Introduce a new call into the zfcp erp to solve this: The function
zfcp_erp_unit_shutdown_wait will close the LUN and wait for the erp to
finish without acquiring an additional reference. The wait allows to
omit the reference; the caller waiting for the erp to finish already
has a reference that holds the struct in place.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/s390/scsi/zfcp_erp.c
drivers/s390/scsi/zfcp_ext.h

index 160b432..50514b4 100644 (file)
@@ -21,6 +21,7 @@ enum zfcp_erp_act_flags {
        ZFCP_STATUS_ERP_DISMISSING      = 0x00100000,
        ZFCP_STATUS_ERP_DISMISSED       = 0x00200000,
        ZFCP_STATUS_ERP_LOWMEM          = 0x00400000,
+       ZFCP_STATUS_ERP_NO_REF          = 0x00800000,
 };
 
 enum zfcp_erp_steps {
@@ -169,22 +170,22 @@ static int zfcp_erp_required_act(int want, struct zfcp_adapter *adapter,
        return need;
 }
 
-static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
+static struct zfcp_erp_action *zfcp_erp_setup_act(int need, u32 act_status,
                                                  struct zfcp_adapter *adapter,
                                                  struct zfcp_port *port,
                                                  struct zfcp_unit *unit)
 {
        struct zfcp_erp_action *erp_action;
-       u32 status = 0;
 
        switch (need) {
        case ZFCP_ERP_ACTION_REOPEN_UNIT:
-               if (!get_device(&unit->dev))
-                       return NULL;
+               if (!(act_status & ZFCP_STATUS_ERP_NO_REF))
+                       if (!get_device(&unit->dev))
+                               return NULL;
                atomic_set_mask(ZFCP_STATUS_COMMON_ERP_INUSE, &unit->status);
                erp_action = &unit->erp_action;
                if (!(atomic_read(&unit->status) & ZFCP_STATUS_COMMON_RUNNING))
-                       status = ZFCP_STATUS_ERP_CLOSE_ONLY;
+                       act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;
 
        case ZFCP_ERP_ACTION_REOPEN_PORT:
@@ -195,7 +196,7 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
                atomic_set_mask(ZFCP_STATUS_COMMON_ERP_INUSE, &port->status);
                erp_action = &port->erp_action;
                if (!(atomic_read(&port->status) & ZFCP_STATUS_COMMON_RUNNING))
-                       status = ZFCP_STATUS_ERP_CLOSE_ONLY;
+                       act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;
 
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
@@ -205,7 +206,7 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
                erp_action = &adapter->erp_action;
                if (!(atomic_read(&adapter->status) &
                      ZFCP_STATUS_COMMON_RUNNING))
-                       status = ZFCP_STATUS_ERP_CLOSE_ONLY;
+                       act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;
 
        default:
@@ -217,14 +218,15 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
        erp_action->port = port;
        erp_action->unit = unit;
        erp_action->action = need;
-       erp_action->status = status;
+       erp_action->status = act_status;
 
        return erp_action;
 }
 
 static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
                                   struct zfcp_port *port,
-                                  struct zfcp_unit *unit, char *id, void *ref)
+                                  struct zfcp_unit *unit, char *id, void *ref,
+                                  u32 act_status)
 {
        int retval = 1, need;
        struct zfcp_erp_action *act = NULL;
@@ -236,10 +238,10 @@ static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
        if (!need)
                goto out;
 
-       atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_PENDING, &adapter->status);
-       act = zfcp_erp_setup_act(need, adapter, port, unit);
+       act = zfcp_erp_setup_act(need, act_status, adapter, port, unit);
        if (!act)
                goto out;
+       atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_PENDING, &adapter->status);
        ++adapter->erp_total_count;
        list_add_tail(&act->list, &adapter->erp_ready_head);
        wake_up(&adapter->erp_ready_wq);
@@ -262,7 +264,7 @@ static int _zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter,
                return -EIO;
        }
        return zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER,
-                                      adapter, NULL, NULL, id, ref);
+                                      adapter, NULL, NULL, id, ref, 0);
 }
 
 /**
@@ -285,7 +287,7 @@ void zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter, int clear,
                zfcp_erp_adapter_failed(adapter, "erareo1", NULL);
        else
                zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER, adapter,
-                                       NULL, NULL, id, ref);
+                                       NULL, NULL, id, ref, 0);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
 }
 
@@ -317,20 +319,6 @@ void zfcp_erp_port_shutdown(struct zfcp_port *port, int clear, char *id,
        zfcp_erp_port_reopen(port, clear | flags, id, ref);
 }
 
-/**
- * zfcp_erp_unit_shutdown - Shutdown unit
- * @unit: Unit to shut down.
- * @clear: Status flags to clear.
- * @id: Id for debug trace event.
- * @ref: Reference for debug trace event.
- */
-void zfcp_erp_unit_shutdown(struct zfcp_unit *unit, int clear, char *id,
-                           void *ref)
-{
-       int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
-       zfcp_erp_unit_reopen(unit, clear | flags, id, ref);
-}
-
 static void zfcp_erp_port_block(struct zfcp_port *port, int clear)
 {
        zfcp_erp_modify_port_status(port, "erpblk1", NULL,
@@ -348,7 +336,7 @@ static void _zfcp_erp_port_forced_reopen(struct zfcp_port *port,
                return;
 
        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT_FORCED,
-                               port->adapter, port, NULL, id, ref);
+                               port->adapter, port, NULL, id, ref, 0);
 }
 
 /**
@@ -381,7 +369,7 @@ static int _zfcp_erp_port_reopen(struct zfcp_port *port, int clear, char *id,
        }
 
        return zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT,
-                                      port->adapter, port, NULL, id, ref);
+                                      port->adapter, port, NULL, id, ref, 0);
 }
 
 /**
@@ -412,7 +400,7 @@ static void zfcp_erp_unit_block(struct zfcp_unit *unit, int clear_mask)
 }
 
 static void _zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
-                                 void *ref)
+                                 void *ref, u32 act_status)
 {
        struct zfcp_adapter *adapter = unit->port->adapter;
 
@@ -422,7 +410,7 @@ static void _zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
                return;
 
        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_UNIT,
-                               adapter, unit->port, unit, id, ref);
+                               adapter, unit->port, unit, id, ref, act_status);
 }
 
 /**
@@ -439,8 +427,45 @@ void zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
        struct zfcp_adapter *adapter = port->adapter;
 
        write_lock_irqsave(&adapter->erp_lock, flags);
-       _zfcp_erp_unit_reopen(unit, clear, id, ref);
+       _zfcp_erp_unit_reopen(unit, clear, id, ref, 0);
+       write_unlock_irqrestore(&adapter->erp_lock, flags);
+}
+
+/**
+ * zfcp_erp_unit_shutdown - Shutdown unit
+ * @unit: Unit to shut down.
+ * @clear: Status flags to clear.
+ * @id: Id for debug trace event.
+ * @ref: Reference for debug trace event.
+ */
+void zfcp_erp_unit_shutdown(struct zfcp_unit *unit, int clear, char *id,
+                           void *ref)
+{
+       int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
+       zfcp_erp_unit_reopen(unit, clear | flags, id, ref);
+}
+
+/**
+ * zfcp_erp_unit_shutdown_wait - Shutdown unit and wait for erp completion
+ * @unit: Unit to shut down.
+ * @id: Id for debug trace event.
+ *
+ * Do not acquire a reference for the unit when creating the ERP
+ * action. It is safe, because this function waits for the ERP to
+ * complete first.
+ */
+void zfcp_erp_unit_shutdown_wait(struct zfcp_unit *unit, char *id)
+{
+       unsigned long flags;
+       struct zfcp_port *port = unit->port;
+       struct zfcp_adapter *adapter = port->adapter;
+       int clear = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
+
+       write_lock_irqsave(&adapter->erp_lock, flags);
+       _zfcp_erp_unit_reopen(unit, clear, id, NULL, ZFCP_STATUS_ERP_NO_REF);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
+
+       zfcp_erp_wait(adapter);
 }
 
 static int status_change_set(unsigned long mask, atomic_t *status)
@@ -566,7 +591,7 @@ static void _zfcp_erp_unit_reopen_all(struct zfcp_port *port, int clear,
 
        read_lock(&port->unit_list_lock);
        list_for_each_entry(unit, &port->unit_list, list)
-               _zfcp_erp_unit_reopen(unit, clear, id, ref);
+               _zfcp_erp_unit_reopen(unit, clear, id, ref, 0);
        read_unlock(&port->unit_list_lock);
 }
 
@@ -583,7 +608,7 @@ static void zfcp_erp_strategy_followup_failed(struct zfcp_erp_action *act)
                _zfcp_erp_port_reopen(act->port, 0, "ersff_3", NULL);
                break;
        case ZFCP_ERP_ACTION_REOPEN_UNIT:
-               _zfcp_erp_unit_reopen(act->unit, 0, "ersff_4", NULL);
+               _zfcp_erp_unit_reopen(act->unit, 0, "ersff_4", NULL, 0);
                break;
        }
 }
@@ -1143,7 +1168,7 @@ static int zfcp_erp_strategy_statechange(struct zfcp_erp_action *act, int ret)
                if (zfcp_erp_strat_change_det(&unit->status, erp_status)) {
                        _zfcp_erp_unit_reopen(unit,
                                              ZFCP_STATUS_COMMON_ERP_FAILED,
-                                             "ersscg3", NULL);
+                                             "ersscg3", NULL, 0);
                        return ZFCP_ERP_EXIT;
                }
                break;
@@ -1191,7 +1216,8 @@ static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result)
 
        switch (act->action) {
        case ZFCP_ERP_ACTION_REOPEN_UNIT:
-               put_device(&unit->dev);
+               if (!(act->status & ZFCP_STATUS_ERP_NO_REF))
+                       put_device(&unit->dev);
                break;
 
        case ZFCP_ERP_ACTION_REOPEN_PORT:
index 5c3966e..3c90604 100644 (file)
@@ -80,6 +80,7 @@ extern void zfcp_erp_modify_unit_status(struct zfcp_unit *, char *, void *, u32,
                                        int);
 extern void zfcp_erp_unit_reopen(struct zfcp_unit *, int, char *, void *);
 extern void zfcp_erp_unit_shutdown(struct zfcp_unit *, int, char *, void *);
+extern void zfcp_erp_unit_shutdown_wait(struct zfcp_unit *, char *);
 extern void zfcp_erp_unit_failed(struct zfcp_unit *, char *, void *);
 extern int  zfcp_erp_thread_setup(struct zfcp_adapter *);
 extern void zfcp_erp_thread_kill(struct zfcp_adapter *);