[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 c89dbe25037..2433eaced20 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 = {