People are inclined to stuff random things into cb->args[n] because it
looks like an array of integers. Sometimes people even put u64s in there
with comments noting that a certain member takes up two slots. The
horror! Really this should mirror the usage of skb->cb, which are just
48 opaque bytes suitable for casting a struct. Then people can create
their usual casting macros for accessing strongly typed members of a
struct.
As a plus, this also gives us the same amount of space on 32bit and 64bit.
Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>
Cc: Johannes Berg <johan...@sipsolutions.net>
---
include/linux/netlink.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 593d1b9c33a8..205fa7b1f07a 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -192,7 +192,14 @@ struct netlink_callback {
bool strict_check;
u16 answer_flags;
unsigned int prev_seq, seq;
- long args[6];
+ union {
+ u8 ctx[48];
+
+ /* args is deprecated. Cast a struct over ctx instead
+ * for proper type safety.
+ */
+ long args[6];
+ };
};
struct netlink_notify {
--
2.21.0
