net: rds: add option for GCOV profiling

To better our unit tests we need code coverage to be part of the kernel.
This patch borrows heavily from how CONFIG_GCOV_PROFILE_FTRACE is
implemented

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/Kconfig

@@ -26,3 +26,12 @@ config RDS_DEBUG
 	bool "RDS debugging messages"
 	depends on RDS
 	default n
+
+config GCOV_PROFILE_RDS
+	bool "Enable GCOV profiling on RDS"
+	depends on GCOV_KERNEL
+	help
+	  Enable GCOV profiling on RDS for checking which functions/lines
+	  are executed.
+
+	  If unsure, say N.

net/rds/Makefile

@@ -15,3 +15,8 @@ rds_tcp-y :=		tcp.o tcp_connect.o tcp_listen.o tcp_recv.o \
 			tcp_send.o tcp_stats.o
 
 ccflags-$(CONFIG_RDS_DEBUG)	:=	-DRDS_DEBUG
+
+# for GCOV coverage profiling
+ifdef CONFIG_GCOV_PROFILE_RDS
+GCOV_PROFILE := y
+endif