kbuild: check license compatibility when building modules

Modules that uses GPL symbols can no longer be build with kbuild,
the build will fail during the modpost step.
When a GPL-incompatible module uses a EXPORT_SYMBOL_GPL_FUTURE symbol
then warn during modpost so author are actually notified.

The actual license compatibility check is shared with the kernel
to make sure it is in sync.

Patch originally from: Andreas Gruenbacher <agruen@suse.de> and
Ram Pai <linuxram@us.ibm.com>

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/license.h b/include/linux/license.h
new file mode 100644
index 000000000000..decdbf43cb5c
--- /dev/null
+++ b/include/linux/license.h
@@ -0,0 +1,14 @@
+#ifndef __LICENSE_H
+#define __LICENSE_H
+
+static inline int license_is_gpl_compatible(const char *license)
+{
+        return (strcmp(license, "GPL") == 0
+                || strcmp(license, "GPL v2") == 0
+                || strcmp(license, "GPL and additional rights") == 0
+                || strcmp(license, "Dual BSD/GPL") == 0
+                || strcmp(license, "Dual MIT/GPL") == 0
+                || strcmp(license, "Dual MPL/GPL") == 0);
+}
+
+#endif