export: fix string handling of namespace in EXPORT_SYMBOL_NS

Commit c3a6cf1 ("export: avoid code duplication in
include/linux/export.h") broke the ability for a defined string to be
used as a namespace value.  Fix this up by using stringify to properly
encode the namespace name.

Fixes: c3a6cf1 ("export: avoid code duplication in include/linux/export.h")
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Cc: Matthias Maennich <maennich@google.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20220427090442.2105905-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/export.h

@@ -2,6 +2,8 @@
 #ifndef _LINUX_EXPORT_H
 #define _LINUX_EXPORT_H
 
+#include <linux/stringify.h>
+
 /*
  * Export symbols from the kernel to modules.  Forked from module.h
  * to reduce the amount of pointless cruft we feed to gcc when only
@@ -154,16 +156,15 @@ struct kernel_symbol {
 #endif /* CONFIG_MODULES */
 
 #ifdef DEFAULT_SYMBOL_NAMESPACE
-#include <linux/stringify.h>
 #define _EXPORT_SYMBOL(sym, sec)	__EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE))
 #else
 #define _EXPORT_SYMBOL(sym, sec)	__EXPORT_SYMBOL(sym, sec, "")
 #endif
 
 #define EXPORT_SYMBOL(sym)		_EXPORT_SYMBOL(sym, "")
 #define EXPORT_SYMBOL_GPL(sym)		_EXPORT_SYMBOL(sym, "_gpl")
-#define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL(sym, "", #ns)
-#define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL(sym, "_gpl", #ns)
+#define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL(sym, "", __stringify(ns))
+#define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL(sym, "_gpl", __stringify(ns))
 
 #endif /* !__ASSEMBLY__ */