eal: add internal ABI tag definition

Introduce the __rte_internal tag to mark internal ABI function which is
used only by the drivers or other libraries.
Like for __rte_experimental, this tag must be on a separate line before
function proprotypes.

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>

devtools/checkpatches.sh

@@ -111,6 +111,37 @@ check_experimental_tags() { # <patch>
 	return $res
 }
 
+check_internal_tags() { # <patch>
+	res=0
+
+	cat "$1" |awk '
+	BEGIN {
+		current_file = "";
+		ret = 0;
+	}
+	/^+++ b\// {
+		current_file = $2;
+	}
+	/^+.*__rte_internal/ {
+		if (current_file ~ ".c$" ) {
+			print "Please only put __rte_internal tags in " \
+				"headers ("current_file")";
+			ret = 1;
+		}
+		if ($1 != "+__rte_internal" || $2 != "") {
+			print "__rte_internal must appear alone on the line" \
+				" immediately preceding the return type of" \
+				" a function."
+			ret = 1;
+		}
+	}
+	END {
+		exit ret;
+	}' || res=1
+
+	return $res
+}
+
 number=0
 range='origin/master..'
 quiet=false
@@ -194,6 +225,14 @@ check () { # <patch> <commit> <title>
 		ret=1
 	fi
 
+	! $verbose || printf '\nChecking __rte_internal tags:\n'
+	report=$(check_internal_tags "$tmpinput")
+	if [ $? -ne 0 ] ; then
+		$headline_printed || print_headline "$3"
+		printf '%s\n' "$report"
+		ret=1
+	fi
+
 	if [ "$tmpinput" != "$1" ]; then
 		rm -f "$tmpinput"
 		trap - INT

lib/librte_eal/include/rte_compat.h

@@ -19,4 +19,17 @@ __attribute__((section(".text.experimental")))
 
 #endif
 
+#ifndef ALLOW_INTERNAL_API
+
+#define __rte_internal \
+__attribute__((error("Symbol is not public ABI"), \
+section(".text.internal")))
+
+#else
+
+#define __rte_internal \
+__attribute__((section(".text.internal")))
+
+#endif
+
 #endif /* _RTE_COMPAT_H_ */