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[v2,11/26] modpost: make multiple export error

Message ID 20220501084032.1025918-12-masahiroy@kernel.org (mailing list archive)
State New
Headers show
Series kbuild: yet another series of cleanups (modpost and LTO) | expand

Commit Message

Masahiro Yamada May 1, 2022, 8:40 a.m. UTC
This is currently a warning, but I think modpost should stop building
in this case.

If the same symbol is exported multiple times and we let it keep going,
the sanity check becomes difficult.

Only the legitimate case is that an external module overrides the
corresponding in-tree module to provide a different implementation
with the same interface.

Also, there exists an upstream example that exploits this feature.

  $ make M=tools/testing/nvdimm

... builds tools/testing/nvdimm/libnvdimm.ko. This is a mocked module
that overrides the symbols from drivers/nvdimm/libnvdimm.ko.

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

Changes in v2:
  - Add more commit description

 scripts/mod/modpost.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 4ce8d164b8e0..1f01fc942f94 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -417,9 +417,9 @@  static struct symbol *sym_add_exported(const char *name, struct module *mod,
 		list_add_tail(&s->list, &mod->exported_symbols);
 	} else if (!external_module || s->module->is_vmlinux ||
 		   s->module == mod) {
-		warn("%s: '%s' exported twice. Previous export was in %s%s\n",
-		     mod->name, name, s->module->name,
-		     s->module->is_vmlinux ? "" : ".ko");
+		error("%s: '%s' exported twice. Previous export was in %s%s\n",
+		      mod->name, name, s->module->name,
+		      s->module->is_vmlinux ? "" : ".ko");
 		return s;
 	}