net: sctp: refactor active path selection

This patch just refactors and moves the code for the active
path selection into its own helper function outside of
sctp_assoc_control_transport() which is already big enough.
No functional changes here.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 39579c3..9f1cc6f 100644 (file)
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -55,6 +55,7 @@
 #include <net/sctp/sm.h>
 
 /* Forward declarations for internal functions. */
+static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
 static void sctp_assoc_bh_rcv(struct work_struct *work);
 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
@@ -774,9 +775,6 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
                                  sctp_transport_cmd_t command,
                                  sctp_sn_error_t error)
 {
-       struct sctp_transport *t = NULL;
-       struct sctp_transport *first;
-       struct sctp_transport *second;
        struct sctp_ulpevent *event;
        struct sockaddr_storage addr;
        int spc_state = 0;
@@ -829,13 +827,14 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
                return;
        }
 
-       /* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
-        * user.
+       /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
+        * to the user.
         */
        if (ulp_notify) {
                memset(&addr, 0, sizeof(struct sockaddr_storage));
                memcpy(&addr, &transport->ipaddr,
                       transport->af_specific->sockaddr_len);
+
                event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
                                        0, spc_state, error, GFP_ATOMIC);
                if (event)
@@ -843,60 +842,7 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
        }
 
        /* Select new active and retran paths. */
-
-       /* Look for the two most recently used active transports.
-        *
-        * This code produces the wrong ordering whenever jiffies
-        * rolls over, but we still get usable transports, so we don't
-        * worry about it.
-        */
-       first = NULL; second = NULL;
-
-       list_for_each_entry(t, &asoc->peer.transport_addr_list,
-                       transports) {
-
-               if ((t->state == SCTP_INACTIVE) ||
-                   (t->state == SCTP_UNCONFIRMED) ||
-                   (t->state == SCTP_PF))
-                       continue;
-               if (!first || t->last_time_heard > first->last_time_heard) {
-                       second = first;
-                       first = t;
-               } else if (!second ||
-                          t->last_time_heard > second->last_time_heard)
-                       second = t;
-       }
-
-       /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
-        *
-        * By default, an endpoint should always transmit to the
-        * primary path, unless the SCTP user explicitly specifies the
-        * destination transport address (and possibly source
-        * transport address) to use.
-        *
-        * [If the primary is active but not most recent, bump the most
-        * recently used transport.]
-        */
-       if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
-            (asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
-           first != asoc->peer.primary_path) {
-               second = first;
-               first = asoc->peer.primary_path;
-       }
-
-       if (!second)
-               second = first;
-       /* If we failed to find a usable transport, just camp on the
-        * primary, even if it is inactive.
-        */
-       if (!first) {
-               first = asoc->peer.primary_path;
-               second = asoc->peer.primary_path;
-       }
-
-       /* Set the active and retran transports.  */
-       asoc->peer.active_path = first;
-       asoc->peer.retran_path = second;
+       sctp_select_active_and_retran_path(asoc);
 }
 
 /* Hold a reference to an association. */
@@ -1325,6 +1271,62 @@ void sctp_assoc_update_retran_path(struct sctp_association *asoc)
                 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
 }
 
+static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
+{
+       struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
+
+       /* Look for the two most recently used active transports. */
+       list_for_each_entry(trans, &asoc->peer.transport_addr_list,
+                           transports) {
+               if (trans->state == SCTP_INACTIVE ||
+                   trans->state == SCTP_UNCONFIRMED ||
+                   trans->state == SCTP_PF)
+                       continue;
+               if (trans_pri == NULL ||
+                   trans->last_time_heard > trans_pri->last_time_heard) {
+                       trans_sec = trans_pri;
+                       trans_pri = trans;
+               } else if (trans_sec == NULL ||
+                          trans->last_time_heard > trans_sec->last_time_heard) {
+                       trans_sec = trans;
+               }
+       }
+
+       /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
+        *
+        * By default, an endpoint should always transmit to the primary
+        * path, unless the SCTP user explicitly specifies the
+        * destination transport address (and possibly source transport
+        * address) to use. [If the primary is active but not most recent,
+        * bump the most recently used transport.]
+        */
+       if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
+            asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
+            asoc->peer.primary_path != trans_pri) {
+               trans_sec = trans_pri;
+               trans_pri = asoc->peer.primary_path;
+       }
+
+       /* We did not find anything useful for a possible retransmission
+        * path; either primary path that we found is the the same as
+        * the current one, or we didn't generally find an active one.
+        */
+       if (trans_sec == NULL)
+               trans_sec = trans_pri;
+
+       /* If we failed to find a usable transport, just camp on the
+        * primary, even if they are inactive.
+        */
+       if (trans_pri == NULL) {
+               trans_pri = asoc->peer.primary_path;
+               trans_sec = asoc->peer.primary_path;
+       }
+
+       /* Set the active and retran transports. */
+       asoc->peer.active_path = trans_pri;
+       asoc->peer.retran_path = trans_sec;
+}
+
 struct sctp_transport *
 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
                                  struct sctp_transport *last_sent_to)