xen: Add __attribute__((format(printf... where appropriate

Use the compiler to verify printf formats and arguments.

Fix fallout.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkback/xenbus.c

@@ -684,7 +684,7 @@ again:
 
 	err = xenbus_switch_state(dev, XenbusStateConnected);
 	if (err)
-		xenbus_dev_fatal(dev, err, "switching to Connected state",
+		xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
 				 dev->nodename);
 
 	return;

include/xen/hvc-console.h

@@ -6,11 +6,13 @@ extern struct console xenboot_console;
 #ifdef CONFIG_HVC_XEN
 void xen_console_resume(void);
 void xen_raw_console_write(const char *str);
+__attribute__((format(printf, 1, 2)))
 void xen_raw_printk(const char *fmt, ...);
 #else
 static inline void xen_console_resume(void) { }
 static inline void xen_raw_console_write(const char *str) { }
-static inline void xen_raw_printk(const char *fmt, ...) { }
+static inline __attribute__((format(printf, 1, 2)))
+void xen_raw_printk(const char *fmt, ...) { }
 #endif
 
 #endif	/* XEN_HVC_CONSOLE_H */

include/xen/xenbus.h

@@ -223,7 +223,9 @@ int xenbus_free_evtchn(struct xenbus_device *dev, int port);
 
 enum xenbus_state xenbus_read_driver_state(const char *path);
 
+__attribute__((format(printf, 3, 4)))
 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...);
+__attribute__((format(printf, 3, 4)))
 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...);
 
 const char *xenbus_strstate(enum xenbus_state state);