2.4.0 struct sock contains a member
which is currently only used for pointing to an in-kernel RPC layer
Is it o.k. to use this pointer for alternative upper layer or would that
be a bad idea?
I have implemented a framework that allows tunneling of PPP and IP over
PF_X25 socket connections. For this I need a pointer to a socket tunnel
structure which I currently maintain in the private x25 protocol block.
As this code is generic (it is not x25 specific and aims at being
re-usable for tunneling over other linux network protocol stacks), it
makes sense to maintain the pointer in a protocol-independent area of
RPC already uses the sk->user_data field to point to an upper layer
control structure. My tunnel scenario is similar: it is also an alternative
(not a struct socket) in-kernel upper layer.
As the type is void*, it seems to me that it was intended for such use.
And there won't be any conflicts with RPC because a socket attached to
in-kernel RPC won't be simultaneously used for tunneling.
Thus, if it's o.k to re-use sk->user_data, I'd like to document this in
the source by means of the following patch.
--- sktn/include/net/sock.h.old Mon Nov 20 22:45:24 2000
+++ sktn/include/net/sock.h Tue Nov 21 22:38:14 2000
@@ -651,7 +651,7 @@
/* Identd and reporting IO signals */
struct socket *socket;
- /* RPC layer private data */
+ /* Private data for non-socket upper layer (e.g. in-kernel RPC) */
/* Callbacks */