[SCSI] zfcp: Send ELS ADISC from workqueue

Issue ELS ADISC requests from workqueue. This allows the link test
request to be sent when the request queue is full due to I/O load for
other remote ports. It also simplifies request queue locking,
zfcp_fsf_send_fcp_command_task is now the only function that has
interrupts disabled from the caller. This is also a prereq for the FC
passthrough support that issues ELS requests from userspace.

Acked-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, 27 insertions, 22 deletions

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 969a3f093037..1e16ab58b242 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -604,6 +604,7 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
         init_waitqueue_head(&port->remove_wq);
         INIT_LIST_HEAD(&port->unit_list_head);
         INIT_WORK(&port->gid_pn_work, zfcp_erp_port_strategy_open_lookup);
+        INIT_WORK(&port->test_link_work, zfcp_fc_link_test_work);
 
         port->adapter = adapter;
         port->d_id = d_id;
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index ff15f11923e9..8412bb992ea1 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -513,6 +513,7 @@ struct zfcp_port {
         u32                    maxframe_size;
         u32                    supported_classes;
         struct work_struct     gid_pn_work;
+        struct work_struct     test_link_work;
 };
 
 struct zfcp_unit {
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index 799ce1db1f56..a2b4987ac652 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -101,6 +101,7 @@ extern void zfcp_fc_incoming_els(struct zfcp_fsf_req *);
 extern int zfcp_fc_ns_gid_pn(struct zfcp_erp_action *);
 extern void zfcp_fc_plogi_evaluate(struct zfcp_port *, struct fsf_plogi *);
 extern void zfcp_test_link(struct zfcp_port *);
+extern void zfcp_fc_link_test_work(struct work_struct *);
 extern void zfcp_fc_nameserver_init(struct zfcp_adapter *);
 
 /* zfcp_fsf.c */
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 67e6b7177870..0f435ed9d1a0 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -421,19 +421,12 @@ static int zfcp_fc_adisc(struct zfcp_port *port)
         return zfcp_fsf_send_els(&adisc->els);
 }
 
-/**
- * zfcp_test_link - lightweight link test procedure
- * @port: port to be tested
- *
- * Test status of a link to a remote port using the ELS command ADISC.
- * If there is a problem with the remote port, error recovery steps
- * will be triggered.
- */
-void zfcp_test_link(struct zfcp_port *port)
+void zfcp_fc_link_test_work(struct work_struct *work)
 {
+        struct zfcp_port *port =
+                container_of(work, struct zfcp_port, test_link_work);
         int retval;
 
-        zfcp_port_get(port);
         retval = zfcp_fc_adisc(port);
         if (retval == 0)
                 return;
@@ -444,6 +437,21 @@ void zfcp_test_link(struct zfcp_port *port)
                 zfcp_erp_port_forced_reopen(port, 0, 65, NULL);
 }
 
+/**
+ * zfcp_test_link - lightweight link test procedure
+ * @port: port to be tested
+ *
+ * Test status of a link to a remote port using the ELS command ADISC.
+ * If there is a problem with the remote port, error recovery steps
+ * will be triggered.
+ */
+void zfcp_test_link(struct zfcp_port *port)
+{
+        zfcp_port_get(port);
+        if (!queue_work(zfcp_data.work_queue, &port->test_link_work))
+                zfcp_port_put(port);
+}
+
 static void zfcp_free_sg_env(struct zfcp_gpn_ft *gpn_ft, int buf_num)
 {
         struct scatterlist *sg = &gpn_ft->sg_req;
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index cc69db3b71e7..9c3f91a343f3 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -647,14 +647,6 @@ static void zfcp_fsf_exchange_port_data_handler(struct zfcp_fsf_req *req)
         }
 }
 
-static int zfcp_fsf_sbal_available(struct zfcp_adapter *adapter)
-{
-        if (atomic_read(&adapter->req_q.count) > 0)
-                return 1;
-        atomic_inc(&adapter->qdio_outb_full);
-        return 0;
-}
-
 static int zfcp_fsf_req_sbal_get(struct zfcp_adapter *adapter)
         __releases(&adapter->req_q_lock)
         __acquires(&adapter->req_q_lock)
@@ -1177,8 +1169,8 @@ int zfcp_fsf_send_els(struct zfcp_send_els *els)
                        ZFCP_STATUS_COMMON_UNBLOCKED)))
                 return -EBUSY;
 
-        spin_lock(&adapter->req_q_lock);
-        if (!zfcp_fsf_sbal_available(adapter))
+        spin_lock_bh(&adapter->req_q_lock);
+        if (zfcp_fsf_req_sbal_get(adapter))
                 goto out;
         req = zfcp_fsf_req_create(adapter, FSF_QTCB_SEND_ELS,
                                   ZFCP_REQ_AUTO_CLEANUP, NULL);
@@ -1211,7 +1203,7 @@ int zfcp_fsf_send_els(struct zfcp_send_els *els)
 failed_send:
         zfcp_fsf_req_free(req);
 out:
-        spin_unlock(&adapter->req_q_lock);
+        spin_unlock_bh(&adapter->req_q_lock);
         return ret;
 }
 
@@ -2324,8 +2316,10 @@ int zfcp_fsf_send_fcp_command_task(struct zfcp_unit *unit,
                 return -EBUSY;
 
         spin_lock(&adapter->req_q_lock);
-        if (!zfcp_fsf_sbal_available(adapter))
+        if (atomic_read(&adapter->req_q.count) <= 0) {
+                atomic_inc(&adapter->qdio_outb_full);
                 goto out;
+        }
         req = zfcp_fsf_req_create(adapter, FSF_QTCB_FCP_CMND,
                                   ZFCP_REQ_AUTO_CLEANUP,
                                   adapter->pool.fsf_req_scsi);