[SCSI] zfcp: Dont block zfcp_wq with scan

When running the scsi_scan from the zfcp workqueue and the target
device does not respond, the zfcp workqueue can block until the
scsi_scan hits a timeout. Move the work to the scsi host workqueue,
since this one is also used for the scan from the SCSI midlayer.

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

5 files changed, 25 insertions, 50 deletions

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 616c60ffcf2c..5a01ef9aeb66 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -97,9 +97,7 @@ static void __init zfcp_init_device_configure(char *busid, u64 wwpn, u64 lun)
         ccw_device_set_online(adapter->ccw_device);
 
         zfcp_erp_wait(adapter);
-        wait_event(adapter->erp_done_wqh,
-                   !(atomic_read(&unit->status) &
-                                ZFCP_STATUS_UNIT_SCSI_WORK_PENDING));
+        flush_work(&unit->scsi_work);
 
         down(&zfcp_data.config_sema);
         zfcp_unit_put(unit);
@@ -279,6 +277,7 @@ struct zfcp_unit *zfcp_unit_enqueue(struct zfcp_port *port, u64 fcp_lun)
 
         atomic_set(&unit->refcount, 0);
         init_waitqueue_head(&unit->remove_wq);
+        INIT_WORK(&unit->scsi_work, zfcp_scsi_scan);
 
         unit->port = port;
         unit->fcp_lun = fcp_lun;
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index a0318630f047..4c362a9069f0 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -255,7 +255,6 @@ enum zfcp_wka_status {
 /* logical unit status */
 #define ZFCP_STATUS_UNIT_SHARED                 0x00000004
 #define ZFCP_STATUS_UNIT_READONLY               0x00000008
-#define ZFCP_STATUS_UNIT_SCSI_WORK_PENDING      0x00000020
 
 /* FSF request status (this does not have a common part) */
 #define ZFCP_STATUS_FSFREQ_TASK_MANAGEMENT      0x00000002
@@ -530,6 +529,7 @@ struct zfcp_unit {
         struct zfcp_erp_action erp_action;     /* pending error recovery */
         atomic_t               erp_counter;
         struct zfcp_latencies   latencies;
+        struct work_struct      scsi_work;
 };
 
 /* FSF request */
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 631bdb1dfd6c..4e160523c31b 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -1176,48 +1176,6 @@ static void zfcp_erp_action_dequeue(struct zfcp_erp_action *erp_action)
         }
 }
 
-struct zfcp_erp_add_work {
-        struct zfcp_unit  *unit;
-        struct work_struct work;
-};
-
-static void zfcp_erp_scsi_scan(struct work_struct *work)
-{
-        struct zfcp_erp_add_work *p =
-                container_of(work, struct zfcp_erp_add_work, work);
-        struct zfcp_unit *unit = p->unit;
-        struct fc_rport *rport = unit->port->rport;
-
-        if (rport && rport->port_state == FC_PORTSTATE_ONLINE)
-                scsi_scan_target(&rport->dev, 0, rport->scsi_target_id,
-                         scsilun_to_int((struct scsi_lun *)&unit->fcp_lun), 0);
-        atomic_clear_mask(ZFCP_STATUS_UNIT_SCSI_WORK_PENDING, &unit->status);
-        zfcp_unit_put(unit);
-        wake_up(&unit->port->adapter->erp_done_wqh);
-        kfree(p);
-}
-
-static void zfcp_erp_schedule_work(struct zfcp_unit *unit)
-{
-        struct zfcp_erp_add_work *p;
-
-        p = kzalloc(sizeof(*p), GFP_KERNEL);
-        if (!p) {
-                dev_err(&unit->port->adapter->ccw_device->dev,
-                        "Registering unit 0x%016Lx on port 0x%016Lx failed\n",
-                        (unsigned long long)unit->fcp_lun,
-                        (unsigned long long)unit->port->wwpn);
-                return;
-        }
-
-        zfcp_unit_get(unit);
-        atomic_set_mask(ZFCP_STATUS_UNIT_SCSI_WORK_PENDING, &unit->status);
-        INIT_WORK(&p->work, zfcp_erp_scsi_scan);
-        p->unit = unit;
-        if (!queue_work(zfcp_data.work_queue, &p->work))
-                zfcp_unit_put(unit);
-}
-
 static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result)
 {
         struct zfcp_adapter *adapter = act->adapter;
@@ -1226,11 +1184,11 @@ static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result)
 
         switch (act->action) {
         case ZFCP_ERP_ACTION_REOPEN_UNIT:
-                flush_work(&port->rport_work);
                 if ((result == ZFCP_ERP_SUCCEEDED) && !unit->device) {
-                        if (!(atomic_read(&unit->status) &
-                              ZFCP_STATUS_UNIT_SCSI_WORK_PENDING))
-                                zfcp_erp_schedule_work(unit);
+                        zfcp_unit_get(unit);
+                        if (scsi_queue_work(unit->port->adapter->scsi_host,
+                                            &unit->scsi_work) <= 0)
+                                zfcp_unit_put(unit);
                 }
                 zfcp_unit_put(unit);
                 break;
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index f6399ca97bcb..df740f10d26a 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -158,6 +158,7 @@ extern void zfcp_scsi_rport_work(struct work_struct *);
 extern void zfcp_scsi_schedule_rport_register(struct zfcp_port *);
 extern void zfcp_scsi_schedule_rport_block(struct zfcp_port *);
 extern void zfcp_scsi_schedule_rports_block(struct zfcp_adapter *);
+extern void zfcp_scsi_scan(struct work_struct *);
 
 /* zfcp_sysfs.c */
 extern struct attribute_group zfcp_sysfs_unit_attrs;
diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index 58201e1ae478..5b11386d70bb 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -583,6 +583,23 @@ void zfcp_scsi_rport_work(struct work_struct *work)
 }
 
 
+void zfcp_scsi_scan(struct work_struct *work)
+{
+        struct zfcp_unit *unit = container_of(work, struct zfcp_unit,
+                                              scsi_work);
+        struct fc_rport *rport;
+
+        flush_work(&unit->port->rport_work);
+        rport = unit->port->rport;
+
+        if (rport && rport->port_state == FC_PORTSTATE_ONLINE)
+                scsi_scan_target(&rport->dev, 0, rport->scsi_target_id,
+                                 scsilun_to_int((struct scsi_lun *)
+                                                &unit->fcp_lun), 0);
+
+        zfcp_unit_put(unit);
+}
+
 struct fc_function_template zfcp_transport_functions = {
         .show_starget_port_id = 1,
         .show_starget_port_name = 1,