tipc: simplify endianness handling in topology subscriber

Because of the requirement for total distribution transparency, users
send subscriptions and receive topology events in their own host format.
It is up to the topology server to determine this format and do the
correct conversions to and from its own host format when needed.

Until now, this has been handled in a rather non-transparent way inside
the topology server and subscriber code, leading to unnecessary
complexity when creating subscriptions and issuing events.

We now improve this situation by adding two new macros, tipc_sub_read()
and tipc_evt_write(). Both those functions calculate the need for
conversion internally before performing their respective operations.
Hence, all handling of such conversions become transparent to the rest
of the code.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 23 deletions

diff --git a/net/tipc/server.c b/net/tipc/server.c
index 7933fb92d852..5d231fa8e4b5 100644
--- a/net/tipc/server.c
+++ b/net/tipc/server.c
@@ -98,18 +98,6 @@ static bool connected(struct tipc_conn *con)
         return con && test_bit(CF_CONNECTED, &con->flags);
 }
 
-/**
- * htohl - convert value to endianness used by destination
- * @in: value to convert
- * @swap: non-zero if endianness must be reversed
- *
- * Returns converted value
- */
-static u32 htohl(u32 in, int swap)
-{
-        return swap ? swab32(in) : in;
-}
-
 static void tipc_conn_kref_release(struct kref *kref)
 {
         struct tipc_conn *con = container_of(kref, struct tipc_conn, kref);
@@ -285,21 +273,12 @@ static int tipc_con_rcv_sub(struct tipc_server *srv,
                             struct tipc_subscr *s)
 {
         struct tipc_subscription *sub;
-        bool status;
-        int swap;
-
-        /* Determine subscriber's endianness */
-        swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE |
-                              TIPC_SUB_CANCEL));
 
-        /* Detect & process a subscription cancellation request */
-        if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
-                s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
+        if (tipc_sub_read(s, filter) & TIPC_SUB_CANCEL) {
                 tipc_con_delete_sub(con, s);
                 return 0;
         }
-        status = !(s->filter & htohl(TIPC_SUB_NO_STATUS, swap));
-        sub = tipc_subscrp_subscribe(srv, s, con->conid, swap, status);
+        sub = tipc_subscrp_subscribe(srv, s, con->conid);
         if (!sub)
                 return -1;