[DCCP]: Simplified conditions due to use of enum:8 states

This reaps the benefit of the earlier patch, which changed the type of
CCID 3 states to use enums, in that many conditions are now simplified
and the number of possible (unexpected) values is greatly reduced.

In a few instances, this also allowed to simplify pre-conditions; where
care has been taken to retain logical equivalence.

[DCCP]: Introduce a consistent BUG/WARN message scheme

This refines the existing set of DCCP messages so that
 * BUG(), BUG_ON(), WARN_ON() have meaningful DCCP-specific counterparts
 * DCCP_CRIT (for severe warnings) is not rate-limited
 * DCCP_WARN() is introduced as rate-limited wrapper

Using these allows a faster and cleaner transition to their original
counterparts once the code has matured into a full DCCP implementation.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c
index 44076e0..2601012 100644
--- a/net/dccp/ccids/lib/tfrc_equation.c
+++ b/net/dccp/ccids/lib/tfrc_equation.c
@@ -13,9 +13,8 @@
  */
 
 #include <linux/module.h>
-
 #include <asm/div64.h>
-
+#include "../../dccp.h"
 #include "tfrc.h"
 
 #define TFRC_CALC_X_ARRSIZE 500
@@ -588,8 +587,10 @@
 		/* p should be 0 unless there is a bug in my code */
 		index = 0;
 
-	if (R == 0)
+	if (R == 0) {
+		DCCP_WARN("RTT==0, setting to 1\n");
 		R = 1; /* RTT can't be zero or else divide by zero */
+	}
 
 	BUG_ON(index >= TFRC_CALC_X_ARRSIZE);