Messages in this thread Patch in this message | | | From | Masahiro Yamada <> | Date | Wed, 12 Jan 2022 04:14:00 +0900 | Subject | Re: [PATCH] export: fix string handling of namespace in EXPORT_SYMBOL_NS |
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On Sat, Jan 8, 2022 at 11:04 PM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > Commit c3a6cf19e695 ("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 adding another layer of > indirection to preserve the previous functionality. > > Fixes: c3a6cf19e695 ("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: Masahiro Yamada <yamada.masahiro@socionext.com> > Cc: Matthias Maennich <maennich@google.com> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > --- > Note, I found this while forward porting an out-of-tree Android kernel > patch from 5.4 to 5.10 that used module namespaces to help wall-off vfs > symbols from being used by non-filesystem modules. This issue does not > affect any in-kernel code, so I am not so sure if it really is needed > here, but it does restore the previous functionality that was being used > in older kernels so it might be good to put back in case others want to > do much the same thing. > > include/linux/export.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/export.h b/include/linux/export.h > index 27d848712b90..9a992809f57d 100644 > --- a/include/linux/export.h > +++ b/include/linux/export.h > @@ -162,8 +162,10 @@ struct kernel_symbol { > > #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, "", #ns) > +#define _EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", #ns) > +#define EXPORT_SYMBOL_NS(sym, ns) _EXPORT_SYMBOL_NS(sym, ns) > +#define EXPORT_SYMBOL_NS_GPL(sym, ns) _EXPORT_SYMBOL_NS_GPL(sym, ns) > > #endif /* !__ASSEMBLY__ */ > > -- > 2.34.1 >
I see __stringify() a few files above. So, you can use it here as well.
Does the following code work? (untested)
diff --git a/include/linux/export.h b/include/linux/export.h index 27d848712b90..5910ccb66ca2 100644 --- a/include/linux/export.h +++ b/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 @@ -154,7 +156,6 @@ 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, "") @@ -162,8 +163,8 @@ struct kernel_symbol {
#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__ */
-- Best Regards Masahiro Yamada
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