svc: Move connection limit checking to its own function

Move the code that poaches connections when the connection limit is hit
to a subroutine to make the accept logic path easier to follow. Since this
is in the new connection path, it should not be a performance issue.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 962dbf4..6e9dc8f 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1105,17 +1105,30 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
 
        svc_sock_received(newsvsk);
 
-       /* make sure that we don't have too many active connections.
-        * If we have, something must be dropped.
-        *
-        * There's no point in trying to do random drop here for
-        * DoS prevention. The NFS clients does 1 reconnect in 15
-        * seconds. An attacker can easily beat that.
-        *
-        * The only somewhat efficient mechanism would be if drop
-        * old connections from the same IP first. But right now
-        * we don't even record the client IP in svc_sock.
-        */
+       if (serv->sv_stats)
+               serv->sv_stats->nettcpconn++;
+
+       return &newsvsk->sk_xprt;
+
+failed:
+       sock_release(newsock);
+       return NULL;
+}
+
+/*
+ * Make sure that we don't have too many active connections.  If we
+ * have, something must be dropped.
+ *
+ * There's no point in trying to do random drop here for DoS
+ * prevention. The NFS clients does 1 reconnect in 15 seconds. An
+ * attacker can easily beat that.
+ *
+ * The only somewhat efficient mechanism would be if drop old
+ * connections from the same IP first. But right now we don't even
+ * record the client IP in svc_sock.
+ */
+static void svc_check_conn_limits(struct svc_serv *serv)
+{
        if (serv->sv_tmpcnt > (serv->sv_nrthreads+3)*20) {
                struct svc_sock *svsk = NULL;
                spin_lock_bh(&serv->sv_lock);
@@ -1123,13 +1136,9 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
                        if (net_ratelimit()) {
                                /* Try to help the admin */
                                printk(KERN_NOTICE "%s: too many open TCP "
-                                       "sockets, consider increasing the "
-                                       "number of nfsd threads\n",
-                                                  serv->sv_name);
-                               printk(KERN_NOTICE
-                                      "%s: last TCP connect from %s\n",
-                                      serv->sv_name, __svc_print_addr(sin,
-                                                       buf, sizeof(buf)));
+                                      "sockets, consider increasing the "
+                                      "number of nfsd threads\n",
+                                      serv->sv_name);
                        }
                        /*
                         * Always select the oldest socket. It's not fair,
@@ -1147,17 +1156,7 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
                        svc_sock_enqueue(svsk);
                        svc_sock_put(svsk);
                }
-
        }
-
-       if (serv->sv_stats)
-               serv->sv_stats->nettcpconn++;
-
-       return &newsvsk->sk_xprt;
-
-failed:
-       sock_release(newsock);
-       return NULL;
 }
 
 /*
@@ -1574,6 +1573,8 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
        } else if (test_bit(SK_LISTENER, &svsk->sk_flags)) {
                struct svc_xprt *newxpt;
                newxpt = svsk->sk_xprt.xpt_ops->xpo_accept(&svsk->sk_xprt);
+               if (newxpt)
+                       svc_check_conn_limits(svsk->sk_server);
                svc_sock_received(svsk);
        } else {
                dprintk("svc: server %p, pool %u, socket %p, inuse=%d\n",