rxrpc: Fix client call queueing, waiting for channel

[ Upstream commit 69ffaebb90369ce08657b5aea4896777b9d6e8fc ]

rxrpc_get_client_conn() adds a new call to the front of the waiting_calls
queue if the connection it's going to use already exists.  This is bad as
it allows calls to get starved out.

Fix this by adding to the tail instead.

Also change the other enqueue point in the same function to put it on the
front (ie. when we have a new connection).  This makes the point that in
the case of a new connection the new call goes at the front (though it
doesn't actually matter since the queue should be unoccupied).

Fixes: 45025bceef17 ("rxrpc: Improve management and caching of client connection objects")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 521189f4b6667fee627bf27fb0742882227a51b3..6e419b15a9f835d7d060b54b07ce5ef8c6c6d41e 100644 (file)
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -353,7 +353,7 @@ static int rxrpc_get_client_conn(struct rxrpc_sock *rx,
         * normally have to take channel_lock but we do this before anyone else
         * can see the connection.
         */
-       list_add_tail(&call->chan_wait_link, &candidate->waiting_calls);
+       list_add(&call->chan_wait_link, &candidate->waiting_calls);
 
        if (cp->exclusive) {
                call->conn = candidate;
@@ -432,7 +432,7 @@ found_extant_conn:
        call->conn = conn;
        call->security_ix = conn->security_ix;
        call->service_id = conn->service_id;
-       list_add(&call->chan_wait_link, &conn->waiting_calls);
+       list_add_tail(&call->chan_wait_link, &conn->waiting_calls);
        spin_unlock(&conn->channel_lock);
        _leave(" = 0 [extant %d]", conn->debug_id);
        return 0;