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, 0 deletions

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 1747ccae8e8d..945b4d5d23b3 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -1118,9 +1118,15 @@ static int __init dccp_init(void)
         if (rc)
                 goto out_ackvec_exit;
 
+        rc = ccid_initialize_builtins();
+        if (rc)
+                goto out_sysctl_exit;
+
         dccp_timestamping_init();
 out:
         return rc;
+out_sysctl_exit:
+        dccp_sysctl_exit();
 out_ackvec_exit:
         dccp_ackvec_exit();
 out_free_dccp_mib:
@@ -1143,6 +1149,7 @@ out_free_percpu:
 
 static void __exit dccp_fini(void)
 {
+        ccid_cleanup_builtins();
         dccp_mib_exit();
         free_pages((unsigned long)dccp_hashinfo.bhash,
                    get_order(dccp_hashinfo.bhash_size *