coredump: introduce cn_vprintf()

Turn cn_printf(...) into cn_vprintf(va_list args), reintroduce
cn_printf() as a trivial wrapper.

This simplifies the next change and cn_vprintf() will have more
callers.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/coredump.c

@@ -69,17 +69,13 @@ static int expand_corename(struct core_name *cn)
 	return 0;
 }
 
-static int cn_printf(struct core_name *cn, const char *fmt, ...)
+static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
 {
 	char *cur;
 	int need;
 	int ret;
-	va_list arg;
 
-	va_start(arg, fmt);
 	need = vsnprintf(NULL, 0, fmt, arg);
-	va_end(arg);
-
 	if (likely(need < cn->size - cn->used - 1))
 		goto out_printf;
 
@@ -89,16 +85,26 @@ static int cn_printf(struct core_name *cn, const char *fmt, ...)
 
 out_printf:
 	cur = cn->corename + cn->used;
-	va_start(arg, fmt);
 	vsnprintf(cur, need + 1, fmt, arg);
-	va_end(arg);
 	cn->used += need;
 	return 0;
 
 expand_fail:
 	return ret;
 }
 
+static int cn_printf(struct core_name *cn, const char *fmt, ...)
+{
+	va_list arg;
+	int ret;
+
+	va_start(arg, fmt);
+	ret = cn_vprintf(cn, fmt, arg);
+	va_end(arg);
+
+	return ret;
+}
+
 static void cn_escape(char *str)
 {
 	for (; *str; str++)