datapath: Fix race in datapath creation.

Before we create the local port, we should allocate and assign the table.
Otherwise packets sent on the local port before we do so will cause an
OOPS.

This is a theoretical race that has not been observed in practice.

diff --git a/datapath/datapath.c b/datapath/datapath.c
index fb23977..eb3f2d2 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -217,28 +217,30 @@ static int create_dp(int dp_idx, const char __user *devnamep)
        dp = kzalloc(sizeof *dp, GFP_KERNEL);
        if (dp == NULL)
                goto err_put_module;
-
+       INIT_LIST_HEAD(&dp->port_list);
        mutex_init(&dp->mutex);
        dp->dp_idx = dp_idx;
        for (i = 0; i < DP_N_QUEUES; i++)
                skb_queue_head_init(&dp->queues[i]);
        init_waitqueue_head(&dp->waitqueue);
 
+       /* Allocate table. */
+       err = -ENOMEM;
+       rcu_assign_pointer(dp->table, dp_table_create(DP_L1_SIZE));
+       if (!dp->table)
+               goto err_free_dp;
+
        /* Setup our datapath device */
        dp_dev = dp_dev_create(dp, devname, ODPP_LOCAL);
        err = PTR_ERR(dp_dev);
        if (IS_ERR(dp_dev))
-               goto err_free_dp;
-
-       err = -ENOMEM;
-       rcu_assign_pointer(dp->table, dp_table_create(DP_L1_SIZE));
-       if (!dp->table)
-               goto err_destroy_dp_dev;
-       INIT_LIST_HEAD(&dp->port_list);
+               goto err_destroy_table;
 
        err = new_nbp(dp, dp_dev, ODPP_LOCAL);
-       if (err)
+       if (err) {
+               dp_dev_destroy(dp_dev);
                goto err_destroy_table;
+       }
 
        dp->drop_frags = 0;
        dp->stats_percpu = alloc_percpu(struct dp_stats_percpu);
@@ -258,8 +260,6 @@ err_destroy_local_port:
        dp_del_port(dp->ports[ODPP_LOCAL]);
 err_destroy_table:
        dp_table_destroy(dp->table, 0);
-err_destroy_dp_dev:
-       dp_dev_destroy(dp_dev);
 err_free_dp:
        kfree(dp);
 err_put_module: