[PATCH v2 04/26] modpost: traverse modules in order

Masahiro Yamada
2022-05-01T08:44:08Z

Currently, modpost manages modules in a singly linked list; it adds
a new node to the head, and traverses the list from new to old.

It works, but the error messages are shown in the reverse order.

If you have a Makefile like this:

obj-m += foo.o bar.o

then, modpost shows error messages in bar.o, foo.o, in this order.

Use a doubly linked list to keep the order in modules.order; use
list_add_tail() for the node addition and list_for_each_entry() for
the list traverse.

Now that the kernel's list macros have been imported to modpost, I will
use them actively going forward.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---

(no changes since v1)

scripts/mod/modpost.c | 17 ++++++++---------
scripts/mod/modpost.h | 3 ++-
2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index f2d6c152cd3f..553e5cf88fee 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -165,16 +165,17 @@ char *get_line(char **stringp)
}

/* A list of all modules we processed */
-static struct module *modules;
+LIST_HEAD(modules);

static struct module *find_module(const char *modname)
{
struct module *mod;

- for (mod = modules; mod; mod = mod->next)
+ list_for_each_entry(mod, &modules, list) {
if (strcmp(mod->name, modname) == 0)
- break;
- return mod;
+ return mod;
+ }
+ return NULL;
}

static struct module *new_module(const char *modname)
@@ -184,7 +185,6 @@ static struct module *new_module(const char *modname)
mod = NOFAIL(malloc(sizeof(*mod) + strlen(modname) + 1));
memset(mod, 0, sizeof(*mod));

- /* add to list */
strcpy(mod->name, modname);
mod->is_vmlinux = (strcmp(modname, "vmlinux") == 0);

@@ -195,8 +195,7 @@ static struct module *new_module(const char *modname)
*/
mod->is_gpl_compatible = true;

- mod->next = modules;
- modules = mod;
+ list_add_tail(&mod->list, &modules);

return mod;
}
@@ -2477,7 +2476,7 @@ static void write_namespace_deps_files(const char *fname)
struct namespace_list *ns;
struct buffer ns_deps_buf = {};

- for (mod = modules; mod; mod = mod->next) {
+ list_for_each_entry(mod, &modules, list) {

if (mod->from_dump || !mod->missing_namespaces)
continue;
@@ -2568,7 +2567,7 @@ int main(int argc, char **argv)
if (files_source)
read_symbols_from_files(files_source);

- for (mod = modules; mod; mod = mod->next) {
+ list_for_each_entry(mod, &modules, list) {
char fname[PATH_MAX];
int ret;

diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index f21a3782885b..d0a8ab60f413 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -11,6 +11,7 @@
#include <unistd.h>
#include <elf.h>

+#include "list.h"
#include "elfconfig.h"

/* On BSD-alike OSes elf.h defines these according to host's word size */
@@ -109,7 +110,7 @@ void
buf_write(struct buffer *buf, const char *s, int len);

struct module {
- struct module *next;
+ struct list_head list;
bool is_gpl_compatible;
struct symbol *unres;
bool from_dump; /* true if module was loaded from *.symvers */
--
2.32.0