xen/pciback: miscellaneous adjustments

This is a minor bugfix and a set of small cleanups; as it is not clear
whether this needs splitting into pieces (and if so, at what
granularity), it is a single combined patch.
- add a missing return statement to an error path in
  kill_domain_by_device()
- use pci_is_enabled() rather than raw atomic_read()
- remove a bogus attempt to zero-terminate an already zero-terminated
  string
- #define DRV_NAME once uniformly in the shared local header
- make DRIVER_ATTR() variables static
- eliminate a pointless use of list_for_each_entry_safe()
- add MODULE_ALIAS()
- a little bit of constification
- adjust a few messages
- remove stray semicolons from inline function definitions

Signed-off-by: Jan Beulich <jbeulich@suse.com>
[v1: Dropped the resource_size fix, altered the description]
[v2: Fixed cleanpatch.pl comments]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index a0e131a..d095acd 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -15,6 +15,8 @@
 #include <linux/atomic.h>
 #include <xen/interface/io/pciif.h>
 
+#define DRV_NAME	"xen-pciback"
+
 struct pci_dev_entry {
 	struct list_head list;
 	struct pci_dev *dev;
@@ -89,7 +91,7 @@
  *  passthrough - BDFs are exactly like in the host.
  */
 struct xen_pcibk_backend {
-	char *name;
+	const char *name;
 	int (*init)(struct xen_pcibk_device *pdev);
 	void (*free)(struct xen_pcibk_device *pdev);
 	int (*find)(struct pci_dev *pcidev, struct xen_pcibk_device *pdev,
@@ -104,9 +106,9 @@
 			       unsigned int devfn);
 };
 
-extern struct xen_pcibk_backend xen_pcibk_vpci_backend;
-extern struct xen_pcibk_backend xen_pcibk_passthrough_backend;
-extern struct xen_pcibk_backend *xen_pcibk_backend;
+extern const struct xen_pcibk_backend xen_pcibk_vpci_backend;
+extern const struct xen_pcibk_backend xen_pcibk_passthrough_backend;
+extern const struct xen_pcibk_backend *xen_pcibk_backend;
 
 static inline int xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 					struct pci_dev *dev,
@@ -116,13 +118,14 @@
 	if (xen_pcibk_backend && xen_pcibk_backend->add)
 		return xen_pcibk_backend->add(pdev, dev, devid, publish_cb);
 	return -1;
-};
+}
+
 static inline void xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
 					     struct pci_dev *dev)
 {
 	if (xen_pcibk_backend && xen_pcibk_backend->free)
 		return xen_pcibk_backend->release(pdev, dev);
-};
+}
 
 static inline struct pci_dev *
 xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, unsigned int domain,
@@ -131,7 +134,8 @@
 	if (xen_pcibk_backend && xen_pcibk_backend->get)
 		return xen_pcibk_backend->get(pdev, domain, bus, devfn);
 	return NULL;
-};
+}
+
 /**
 * Add for domain0 PCIE-AER handling. Get guest domain/bus/devfn in xen_pcibk
 * before sending aer request to pcifront, so that guest could identify
@@ -148,25 +152,29 @@
 		return xen_pcibk_backend->find(pcidev, pdev, domain, bus,
 					       devfn);
 	return -1;
-};
+}
+
 static inline int xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
 {
 	if (xen_pcibk_backend && xen_pcibk_backend->init)
 		return xen_pcibk_backend->init(pdev);
 	return -1;
-};
+}
+
 static inline int xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
 					      publish_pci_root_cb cb)
 {
 	if (xen_pcibk_backend && xen_pcibk_backend->publish)
 		return xen_pcibk_backend->publish(pdev, cb);
 	return -1;
-};
+}
+
 static inline void xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
 {
 	if (xen_pcibk_backend && xen_pcibk_backend->free)
 		return xen_pcibk_backend->free(pdev);
-};
+}
+
 /* Handles events from front-end */
 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id);
 void xen_pcibk_do_op(struct work_struct *data);