Commit 700c48b4 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

modpost: use null string instead of NULL pointer for default namespace 



The default namespace is the null string, "".

When set, the null string "" is converted to NULL:

  s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;

When printed, the NULL pointer is get back to the null string:

  sym->namespace ?: ""

This saves 1 byte memory allocated for "", but loses the readability.

In kernel-space, we strive to save memory, but modpost is a userspace
tool used to build the kernel. On modern systems, such small piece of
memory is not a big deal.

Handle the namespace string as is.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
parent 6e7611c4

scripts/mod/modpost.c

+11 −6
Original line number Diff line number Diff line
@@ -300,6 +300,13 @@ static bool contains_namespace(struct list_head *head, const char *namespace) 
{

	struct namespace_list *list;



	/*

	 * The default namespace is null string "", which is always implicitly

	 * contained.

	 */

	if (!namespace[0])

		return true;



	list_for_each_entry(list, head, list) {

		if (!strcmp(list->namespace, namespace))

			return true;
@@ -369,7 +376,7 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod, 
	s = alloc_symbol(name);

	s->module = mod;

	s->is_gpl_only = gpl_only;

	s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;

	s->namespace = NOFAIL(strdup(namespace));

	list_add_tail(&s->list, &mod->exported_symbols);

	hash_add_symbol(s);
@@ -1829,8 +1836,7 @@ static void check_exports(struct module *mod) 
		else

			basename = mod->name;



		if (exp->namespace &&

		    !contains_namespace(&mod->imported_namespaces, exp->namespace)) {

		if (!contains_namespace(&mod->imported_namespaces, exp->namespace)) {

			modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,

				    "module %s uses symbol %s from namespace %s, but does not import it.\n",

				    basename, exp->name, exp->namespace);
@@ -1916,8 +1922,7 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod) 
	list_for_each_entry(sym, &mod->exported_symbols, list)

		buf_printf(buf, "KSYMTAB_%s(%s, \"%s\", \"%s\");\n",

			   sym->is_func ? "FUNC" : "DATA", sym->name,

			   sym->is_gpl_only ? "_gpl" : "",

			   sym->namespace ?: "");

			   sym->is_gpl_only ? "_gpl" : "", sym->namespace);



	if (!modversions)

		return;
@@ -2185,7 +2190,7 @@ static void write_dump(const char *fname) 
			buf_printf(&buf, "0x%08x\t%s\t%s\tEXPORT_SYMBOL%s\t%s\n",

				   sym->crc, sym->name, mod->name,

				   sym->is_gpl_only ? "_GPL" : "",

				   sym->namespace ?: "");

				   sym->namespace);

		}

	}

	write_buf(&buf, fname);