Patch "ceph: fix symbol versioning for ceph_monc_do_statfs" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

ceph: fix symbol versioning for ceph_monc_do_statfs

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ceph-fix-symbol-versioning-for-ceph_monc_do_statfs.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Arnd Bergmann <[email protected]>
Date: Mon, 13 Jun 2016 15:04:56 +0200
Subject: ceph: fix symbol versioning for ceph_monc_do_statfs

From: Arnd Bergmann <[email protected]>

commit a0f2b65275413b3438e9f55b1427273cd893c3b2 upstream.

The genksyms helper in the kernel cannot parse a type definition like "typeof(((type *)0)->keyfld)" that is used in the DEFINE_RB_FUNCS helper, causing the following EXPORT_SYMBOL() statement to be ignored when computing the crcs, and triggering a warning about this:

WARNING: "ceph_monc_do_statfs" [fs/ceph/ceph.ko] has no CRC

To work around the problem, we can rewrite the type to reference an undefined 'extern' symbol instead of a NULL pointer. This is evidently ok for genksyms, and it no longer complains about the line when calling it with 'genksyms -w'.

I've looked briefly into extending genksyms instead, but it seems really hard to do. Jan Beulich introduced basic support for 'typeof' a while ago in dc53324060f3 ("genksyms: fix typeof() handling"), but that is not sufficient for the expression we have here.

---
 include/linux/ceph/libceph.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -214,8 +214,9 @@ static void erase_##name(struct rb_root
 }
 
 #define DEFINE_RB_LOOKUP_FUNC(name, type, keyfld, nodefld)		\
+extern type __lookup_##name##_key;					\
 static type *lookup_##name(struct rb_root *root,			\
-			   typeof(((type *)0)->keyfld) key)		\
+			   typeof(__lookup_##name##_key.keyfld) key)	\
 {									\
 	struct rb_node *n = root->rb_node;				\
 									\

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/ceph-fix-symbol-versioning-for-ceph_monc_do_statfs.patch queue-4.7/x86-efi-only-map-ram-into-efi-page-tables-if-in-mixed-mode.patch queue-4.7/x86-mm-pat-prevent-hang-during-boot-when-mapping-pages.patch queue-4.7/reiserfs-fix-new_insert_key-may-be-used-uninitialized.patch