[NET] fib_rules: Add no-operation action

The use of nop rules simplifies the usage of goto rules
and adds more flexibility as they allow targets to remain
while the actual content of the branches can change easly.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/fib_rules.h

@@ -54,7 +54,7 @@ enum
 	FR_ACT_UNSPEC,
 	FR_ACT_TO_TBL,		/* Pass to fixed table */
 	FR_ACT_GOTO,		/* Jump to another rule */
-	FR_ACT_RES2,
+	FR_ACT_NOP,		/* No operation */
 	FR_ACT_RES3,
 	FR_ACT_RES4,
 	FR_ACT_BLACKHOLE,	/* Drop without notification */

net/core/fib_rules.c

@@ -146,7 +146,9 @@ jumped:
 				rule = target;
 				goto jumped;
 			}
-		} else
+		} else if (rule->action == FR_ACT_NOP)
+			continue;
+		else
 			err = ops->action(rule, fl, flags, arg);
 
 		if (err != -EAGAIN) {