RDMA/cma: Increment port number after close to avoid re-use

Randomize the starting port number and avoid re-using port values
immediately after they are closed.  Instead keep track of the last
port value used and increment it every time a new port number is
assigned, to better replicate other port spaces.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 9e0ab048c878eba5b07d57501762f83c3f1f2356..bc31b54e9cac4f590cdd793e4abab994ddc1686c 100644 (file)
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -71,6 +71,7 @@ static struct workqueue_struct *cma_wq;
 static DEFINE_IDR(sdp_ps);
 static DEFINE_IDR(tcp_ps);
 static DEFINE_IDR(udp_ps);
+static int next_port;
 
 struct cma_device {
        struct list_head        list;
@@ -1722,33 +1723,74 @@ static int cma_alloc_port(struct idr *ps, struct rdma_id_private *id_priv,
                          unsigned short snum)
 {
        struct rdma_bind_list *bind_list;
-       int port, start, ret;
+       int port, ret;
 
        bind_list = kzalloc(sizeof *bind_list, GFP_KERNEL);
        if (!bind_list)
                return -ENOMEM;
 
-       start = snum ? snum : sysctl_local_port_range[0];
+       do {
+               ret = idr_get_new_above(ps, bind_list, snum, &port);
+       } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL));
+
+       if (ret)
+               goto err1;
+
+       if (port != snum) {
+               ret = -EADDRNOTAVAIL;
+               goto err2;
+       }
+
+       bind_list->ps = ps;
+       bind_list->port = (unsigned short) port;
+       cma_bind_port(bind_list, id_priv);
+       return 0;
+err2:
+       idr_remove(ps, port);
+err1:
+       kfree(bind_list);
+       return ret;
+}
 
+static int cma_alloc_any_port(struct idr *ps, struct rdma_id_private *id_priv)
+{
+       struct rdma_bind_list *bind_list;
+       int port, ret;
+
+       bind_list = kzalloc(sizeof *bind_list, GFP_KERNEL);
+       if (!bind_list)
+               return -ENOMEM;
+
+retry:
        do {
-               ret = idr_get_new_above(ps, bind_list, start, &port);
+               ret = idr_get_new_above(ps, bind_list, next_port, &port);
        } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL));
 
        if (ret)
-               goto err;
+               goto err1;
 
-       if ((snum && port != snum) ||
-           (!snum && port > sysctl_local_port_range[1])) {
-               idr_remove(ps, port);
+       if (port > sysctl_local_port_range[1]) {
+               if (next_port != sysctl_local_port_range[0]) {
+                       idr_remove(ps, port);
+                       next_port = sysctl_local_port_range[0];
+                       goto retry;
+               }
                ret = -EADDRNOTAVAIL;
-               goto err;
+               goto err2;
        }
 
+       if (port == sysctl_local_port_range[1])
+               next_port = sysctl_local_port_range[0];
+       else
+               next_port = port + 1;
+
        bind_list->ps = ps;
        bind_list->port = (unsigned short) port;
        cma_bind_port(bind_list, id_priv);
        return 0;
-err:
+err2:
+       idr_remove(ps, port);
+err1:
        kfree(bind_list);
        return ret;
 }
@@ -1811,7 +1853,7 @@ static int cma_get_port(struct rdma_id_private *id_priv)
 
        mutex_lock(&lock);
        if (cma_any_port(&id_priv->id.route.addr.src_addr))
-               ret = cma_alloc_port(ps, id_priv, 0);
+               ret = cma_alloc_any_port(ps, id_priv);
        else
                ret = cma_use_port(ps, id_priv);
        mutex_unlock(&lock);
@@ -2448,6 +2490,10 @@ static int cma_init(void)
 {
        int ret;
 
+       get_random_bytes(&next_port, sizeof next_port);
+       next_port = (next_port % (sysctl_local_port_range[1] -
+                                 sysctl_local_port_range[0])) +
+                   sysctl_local_port_range[0];
        cma_wq = create_singlethread_workqueue("rdma_cm_wq");
        if (!cma_wq)
                return -ENOMEM;