niu: Silence randstruct warnings

Clang randstruct gets upset when it sees struct addresspace (which is
randomized) being assigned to a struct page (which is not randomized):

drivers/net/ethernet/sun/niu.c:3385:12: error: casting from randomized structure pointer type 'struct address_space *' to 'struct page *'
                        *link = (struct page *) page->mapping;
                                ^

It looks like niu.c is looking for an in-line place to chain its allocated
pages together and is overloading the "mapping" member, as it is unused.
This is very non-standard, and is expected to be cleaned up in the
future[1], but there is no "correct" way to handle it today.

No meaningful machine code changes result after this change, and source
readability is improved.

Drop the randstruct exception now that there is no "confusing" cross-type
assignment.

[1] https://lore.kernel.org/lkml/[email protected]/

Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Du Cheng <[email protected]>
Cc: Christophe JAILLET <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Acked-by: Jakub Kicinski <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]
Signed-off-by: Kees Cook <[email protected]>

1 files changed, 0 insertions, 2 deletions

diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index 5836a7fc7532..c9d345a91c41 100644
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -46,8 +46,6 @@ struct whitelist_entry {
 };
 
 static const struct whitelist_entry whitelist[] = {
-	/* NIU overloads mapping with page struct */
-	{ "drivers/net/ethernet/sun/niu.c", "page", "address_space" },
 	/* unix_skb_parms via UNIXCB() buffer */
 	{ "net/unix/af_unix.c", "unix_skb_parms", "char" },
 	{ }