dccp: Lockless integration of CCID congestion-control plugins

Based on Arnaldo's earlier patch, this patch integrates the standardised
CCID congestion control plugins (CCID-2 and CCID-3) of DCCP with dccp.ko:

 * enables a faster connection path by eliminating the need to always go 
   through the CCID registration lock;

 * updates the implementation to use only a single array whose size equals
   the number of configured CCIDs instead of the maximum (256);

 * since the CCIDs are now fixed array elements, synchronization is no
   longer needed, simplifying use and implementation.

CCID-2 is suggested as minimum for a basic DCCP implementation (RFC 4340, 10);
CCID-3 is a standards-track CCID supported by RFC 4342 and RFC 5348.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
index 18f69423a708..75c21c52ed7a 100644
--- a/net/dccp/ccid.h
+++ b/net/dccp/ccid.h
@@ -29,7 +29,6 @@ struct tcp_info;
  *  @ccid_id: numerical CCID ID (up to %CCID_MAX, cf. table 5 in RFC 4340, 10.)
  *  @ccid_ccmps: the CCMPS including network/transport headers (0 when disabled)
  *  @ccid_name: alphabetical identifier string for @ccid_id
- *  @ccid_owner: module which implements/owns this CCID
  *  @ccid_hc_{r,t}x_slab: memory pool for the receiver/sender half-connection
  *  @ccid_hc_{r,t}x_obj_size: size of the receiver/sender half-connection socket
  *
@@ -48,7 +47,6 @@ struct ccid_operations {
         unsigned char           ccid_id;
         __u32                   ccid_ccmps;
         const char              *ccid_name;
-        struct module           *ccid_owner;
         struct kmem_cache       *ccid_hc_rx_slab,
                                 *ccid_hc_tx_slab;
         __u32                   ccid_hc_rx_obj_size,
@@ -90,8 +88,13 @@ struct ccid_operations {
                                                  int __user *optlen);
 };
 
-extern int ccid_register(struct ccid_operations *ccid_ops);
-extern int ccid_unregister(struct ccid_operations *ccid_ops);
+extern struct ccid_operations ccid2_ops;
+#ifdef CONFIG_IP_DCCP_CCID3
+extern struct ccid_operations ccid3_ops;
+#endif
+
+extern int  ccid_initialize_builtins(void);
+extern void ccid_cleanup_builtins(void);
 
 struct ccid {
         struct ccid_operations *ccid_ops;