9p: Reduce object size with CONFIG_NET_9P_DEBUG

Reduce object size by deduplicating formats.

Use vsprintf extension %pV.
Rename P9_DPRINTK uses to p9_debug, align arguments.
Add function for _p9_debug and macro to add __func__.
Add missing "\n"s to p9_debug uses.
Remove embedded function names as p9_debug adds it.
Remove P9_EPRINTK macro and convert use to pr_<level>.
Add and use pr_fmt and pr_<level>.

$ size fs/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  62133	    984	  16000	  79117	  1350d	fs/9p/built-in.o.new
  67342	    984	  16928	  85254	  14d06	fs/9p/built-in.o.old
$ size net/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  88792	   4148	  22024	 114964	  1c114	net/9p/built-in.o.new
  94072	   4148	  23232	 121452	  1da6c	net/9p/built-in.o.old

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
index 2d70b95..7184853 100644
--- a/include/net/9p/9p.h
+++ b/include/net/9p/9p.h
@@ -63,30 +63,16 @@
 
 #ifdef CONFIG_NET_9P_DEBUG
 extern unsigned int p9_debug_level;
-
-#define P9_DPRINTK(level, format, arg...) \
-do {  \
-	if ((p9_debug_level & level) == level) {\
-		if (level == P9_DEBUG_9P) \
-			printk(KERN_NOTICE "(%8.8d) " \
-			format , task_pid_nr(current) , ## arg); \
-		else \
-			printk(KERN_NOTICE "-- %s (%d): " \
-			format , __func__, task_pid_nr(current) , ## arg); \
-	} \
-} while (0)
-
+__printf(3, 4)
+void _p9_debug(enum p9_debug_flags level, const char *func,
+	       const char *fmt, ...);
+#define p9_debug(level, fmt, ...)			\
+	_p9_debug(level, __func__, fmt, ##__VA_ARGS__)
 #else
-#define P9_DPRINTK(level, format, arg...)  do { } while (0)
+#define p9_debug(level, fmt, ...)			\
+	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
-
-#define P9_EPRINTK(level, format, arg...) \
-do { \
-	printk(level "9p: %s (%d): " \
-		format , __func__, task_pid_nr(current), ## arg); \
-} while (0)
-
 /**
  * enum p9_msg_t - 9P message types
  * @P9_TLERROR: not used