[SCSI] zfcp: Remove global config_mutex

The global config_mutex was required for the serialization of a
configuration change within the zfcp driver.  This global locking is
now obsolete and can be removed.  The requirement of serializing the
access to a zfcp_adapter reference via a ccw_device is realized wth a
static spinlock.

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@suse.de>

1 files changed, 76 insertions, 62 deletions

diff --git a/drivers/s390/scsi/zfcp_ccw.c b/drivers/s390/scsi/zfcp_ccw.c
index c89dbe250377..2433eaced20c 100644
--- a/drivers/s390/scsi/zfcp_ccw.c
+++ b/drivers/s390/scsi/zfcp_ccw.c
@@ -13,20 +13,42 @@
 
 #define ZFCP_MODEL_PRIV 0x4
 
+static DEFINE_SPINLOCK(zfcp_ccw_adapter_ref_lock);
+
+struct zfcp_adapter *zfcp_ccw_adapter_by_cdev(struct ccw_device *cdev)
+{
+        struct zfcp_adapter *adapter;
+        unsigned long flags;
+
+        spin_lock_irqsave(&zfcp_ccw_adapter_ref_lock, flags);
+        adapter = dev_get_drvdata(&cdev->dev);
+        if (adapter)
+                kref_get(&adapter->ref);
+        spin_unlock_irqrestore(&zfcp_ccw_adapter_ref_lock, flags);
+        return adapter;
+}
+
+void zfcp_ccw_adapter_put(struct zfcp_adapter *adapter)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&zfcp_ccw_adapter_ref_lock, flags);
+        kref_put(&adapter->ref, zfcp_adapter_release);
+        spin_unlock_irqrestore(&zfcp_ccw_adapter_ref_lock, flags);
+}
+
 static int zfcp_ccw_suspend(struct ccw_device *cdev)
 
 {
-        struct zfcp_adapter *adapter = dev_get_drvdata(&cdev->dev);
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
 
         if (!adapter)
                 return 0;
 
-        mutex_lock(&zfcp_data.config_mutex);
-
         zfcp_erp_adapter_shutdown(adapter, 0, "ccsusp1", NULL);
         zfcp_erp_wait(adapter);
 
-        mutex_unlock(&zfcp_data.config_mutex);
+        zfcp_ccw_adapter_put(adapter);
 
         return 0;
 }
@@ -34,7 +56,7 @@ static int zfcp_ccw_suspend(struct ccw_device *cdev)
 static int zfcp_ccw_activate(struct ccw_device *cdev)
 
 {
-        struct zfcp_adapter *adapter = dev_get_drvdata(&cdev->dev);
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
 
         if (!adapter)
                 return 0;
@@ -46,6 +68,8 @@ static int zfcp_ccw_activate(struct ccw_device *cdev)
         zfcp_erp_wait(adapter);
         flush_work(&adapter->scan_work);
 
+        zfcp_ccw_adapter_put(adapter);
+
         return 0;
 }
 
@@ -67,28 +91,28 @@ int zfcp_ccw_priv_sch(struct zfcp_adapter *adapter)
 
 /**
  * zfcp_ccw_probe - probe function of zfcp driver
- * @ccw_device: pointer to belonging ccw device
+ * @cdev: pointer to belonging ccw device
  *
  * This function gets called by the common i/o layer for each FCP
  * device found on the current system. This is only a stub to make cio
  * work: To only allocate adapter resources for devices actually used,
  * the allocation is deferred to the first call to ccw_set_online.
  */
-static int zfcp_ccw_probe(struct ccw_device *ccw_device)
+static int zfcp_ccw_probe(struct ccw_device *cdev)
 {
         return 0;
 }
 
 /**
  * zfcp_ccw_remove - remove function of zfcp driver
- * @ccw_device: pointer to belonging ccw device
+ * @cdev: pointer to belonging ccw device
  *
  * This function gets called by the common i/o layer and removes an adapter
  * from the system. Task of this function is to get rid of all units and
  * ports that belong to this adapter. And in addition all resources of this
  * adapter will be freed too.
  */
-static void zfcp_ccw_remove(struct ccw_device *ccw_device)
+static void zfcp_ccw_remove(struct ccw_device *cdev)
 {
         struct zfcp_adapter *adapter;
         struct zfcp_port *port, *p;
@@ -96,22 +120,12 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
         LIST_HEAD(unit_remove_lh);
         LIST_HEAD(port_remove_lh);
 
-        ccw_device_set_offline(ccw_device);
-
-        mutex_lock(&zfcp_data.config_mutex);
-        adapter = dev_get_drvdata(&ccw_device->dev);
-        mutex_unlock(&zfcp_data.config_mutex);
+        ccw_device_set_offline(cdev);
 
+        adapter = zfcp_ccw_adapter_by_cdev(cdev);
         if (!adapter)
                 return;
 
-        cancel_work_sync(&adapter->scan_work);
-
-        mutex_lock(&zfcp_data.config_mutex);
-
-        /* this also removes the scsi devices, so call it first */
-        zfcp_adapter_scsi_unregister(adapter);
-
         write_lock_irq(&adapter->port_list_lock);
         list_for_each_entry_safe(port, p, &adapter->port_list, list) {
                 write_lock(&port->unit_list_lock);
@@ -126,7 +140,7 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
         }
         atomic_set_mask(ZFCP_STATUS_COMMON_REMOVE, &adapter->status);
         write_unlock_irq(&adapter->port_list_lock);
-        mutex_unlock(&zfcp_data.config_mutex);
+        zfcp_ccw_adapter_put(adapter); /* put from zfcp_ccw_adapter_by_cdev */
 
         list_for_each_entry_safe(unit, u, &unit_remove_lh, list)
                 zfcp_device_unregister(&unit->sysfs_device,
@@ -136,12 +150,12 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
                 zfcp_device_unregister(&port->sysfs_device,
                                        &zfcp_sysfs_port_attrs);
 
-        kref_put(&adapter->ref, zfcp_adapter_release);
+        zfcp_adapter_unregister(adapter);
 }
 
 /**
  * zfcp_ccw_set_online - set_online function of zfcp driver
- * @ccw_device: pointer to belonging ccw device
+ * @cdev: pointer to belonging ccw device
  *
  * This function gets called by the common i/o layer and sets an
  * adapter into state online.  The first call will allocate all
@@ -152,23 +166,20 @@ static void zfcp_ccw_remove(struct ccw_device *ccw_device)
  * the SCSI stack, that the QDIO queues will be set up and that the
  * adapter will be opened.
  */
-static int zfcp_ccw_set_online(struct ccw_device *ccw_device)
+static int zfcp_ccw_set_online(struct ccw_device *cdev)
 {
-        struct zfcp_adapter *adapter;
-        int ret = 0;
-
-        mutex_lock(&zfcp_data.config_mutex);
-        adapter = dev_get_drvdata(&ccw_device->dev);
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
 
         if (!adapter) {
-                ret = zfcp_adapter_enqueue(ccw_device);
-                if (ret) {
-                        dev_err(&ccw_device->dev,
+                adapter = zfcp_adapter_enqueue(cdev);
+
+                if (IS_ERR(adapter)) {
+                        dev_err(&cdev->dev,
                                 "Setting up data structures for the "
                                 "FCP adapter failed\n");
-                        goto out;
+                        return PTR_ERR(adapter);
                 }
-                adapter = dev_get_drvdata(&ccw_device->dev);
+                kref_get(&adapter->ref);
         }
 
         /* initialize request counter */
@@ -180,58 +191,61 @@ static int zfcp_ccw_set_online(struct ccw_device *ccw_device)
         zfcp_erp_adapter_reopen(adapter, ZFCP_STATUS_COMMON_ERP_FAILED,
                                 "ccsonl2", NULL);
         zfcp_erp_wait(adapter);
-out:
-        mutex_unlock(&zfcp_data.config_mutex);
-        if (!ret)
-                flush_work(&adapter->scan_work);
-        return ret;
+
+        flush_work(&adapter->scan_work);
+
+        zfcp_ccw_adapter_put(adapter);
+        return 0;
 }
 
 /**
  * zfcp_ccw_set_offline - set_offline function of zfcp driver
- * @ccw_device: pointer to belonging ccw device
+ * @cdev: pointer to belonging ccw device
  *
  * This function gets called by the common i/o layer and sets an adapter
  * into state offline.
  */
-static int zfcp_ccw_set_offline(struct ccw_device *ccw_device)
+static int zfcp_ccw_set_offline(struct ccw_device *cdev)
 {
-        struct zfcp_adapter *adapter;
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
+
+        if (!adapter)
+                return 0;
 
-        mutex_lock(&zfcp_data.config_mutex);
-        adapter = dev_get_drvdata(&ccw_device->dev);
         zfcp_erp_adapter_shutdown(adapter, 0, "ccsoff1", NULL);
         zfcp_erp_wait(adapter);
-        mutex_unlock(&zfcp_data.config_mutex);
+
+        zfcp_ccw_adapter_put(adapter);
         return 0;
 }
 
 /**
  * zfcp_ccw_notify - ccw notify function
- * @ccw_device: pointer to belonging ccw device
+ * @cdev: pointer to belonging ccw device
  * @event: indicates if adapter was detached or attached
  *
  * This function gets called by the common i/o layer if an adapter has gone
  * or reappeared.
  */
-static int zfcp_ccw_notify(struct ccw_device *ccw_device, int event)
+static int zfcp_ccw_notify(struct ccw_device *cdev, int event)
 {
-        struct zfcp_adapter *adapter = dev_get_drvdata(&ccw_device->dev);
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
+
+        if (!adapter)
+                return 1;
 
         switch (event) {
         case CIO_GONE:
-                dev_warn(&adapter->ccw_device->dev,
-                         "The FCP device has been detached\n");
+                dev_warn(&cdev->dev, "The FCP device has been detached\n");
                 zfcp_erp_adapter_shutdown(adapter, 0, "ccnoti1", NULL);
                 break;
         case CIO_NO_PATH:
-                dev_warn(&adapter->ccw_device->dev,
+                dev_warn(&cdev->dev,
                          "The CHPID for the FCP device is offline\n");
                 zfcp_erp_adapter_shutdown(adapter, 0, "ccnoti2", NULL);
                 break;
         case CIO_OPER:
-                dev_info(&adapter->ccw_device->dev,
-                         "The FCP device is operational again\n");
+                dev_info(&cdev->dev, "The FCP device is operational again\n");
                 zfcp_erp_modify_adapter_status(adapter, "ccnoti3", NULL,
                                                ZFCP_STATUS_COMMON_RUNNING,
                                                ZFCP_SET);
@@ -239,11 +253,13 @@ static int zfcp_ccw_notify(struct ccw_device *ccw_device, int event)
                                         "ccnoti4", NULL);
                 break;
         case CIO_BOXED:
-                dev_warn(&adapter->ccw_device->dev, "The FCP device "
-                         "did not respond within the specified time\n");
+                dev_warn(&cdev->dev, "The FCP device did not respond within "
+                                     "the specified time\n");
                 zfcp_erp_adapter_shutdown(adapter, 0, "ccnoti5", NULL);
                 break;
         }
+
+        zfcp_ccw_adapter_put(adapter);
         return 1;
 }
 
@@ -253,18 +269,16 @@ static int zfcp_ccw_notify(struct ccw_device *ccw_device, int event)
  */
 static void zfcp_ccw_shutdown(struct ccw_device *cdev)
 {
-        struct zfcp_adapter *adapter;
+        struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(cdev);
 
-        mutex_lock(&zfcp_data.config_mutex);
-        adapter = dev_get_drvdata(&cdev->dev);
         if (!adapter)
-                goto out;
+                return;
 
         zfcp_erp_adapter_shutdown(adapter, 0, "ccshut1", NULL);
         zfcp_erp_wait(adapter);
         zfcp_erp_thread_kill(adapter);
-out:
-        mutex_unlock(&zfcp_data.config_mutex);
+
+        zfcp_ccw_adapter_put(adapter);
 }
 
 struct ccw_driver zfcp_ccw_driver = {