tipc: Elimination of print buffer chaining

This patch revamps TIPC's print buffer subsystem to eliminate
support for arbitrary chains of print buffers, which were
rarely needed and difficult to use safely.

In its place, print buffers can now be configured to echo their
output to the system console.  This provides an equivalent for
the only chaining currently utilized by TIPC, in a faster and
more compact manner.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/dbg.h

@@ -42,14 +42,14 @@
  * @buf: pointer to character array containing print buffer contents
  * @size: size of character array
  * @crs: pointer to first unused space in character array (i.e. final NUL)
- * @next: used to link print buffers when printing to more than one at a time
+ * @echo: echo output to system console if non-zero
  */
 
 struct print_buf {
 	char *buf;
 	u32 size;
 	char *crs;
-	struct print_buf *next;
+	int echo;
 };
 
 #define TIPC_PB_MIN_SIZE 64	/* minimum size for a print buffer's array */