datapath: Add get_vport_protected().

In some places we access the array of datapath ports without
RCU protection.  This introduces a new function to check that in
these case the dp mutex is held for protection.

Found with sparse.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index bf9fc82..4df7e9f 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -94,9 +94,17 @@ static struct datapath *get_dp_locked(int dp_idx)
        return dp;
 }
 
-static struct tbl *get_table_protected(struct datapath *dp)
+static struct tbl *get_table_protected(const struct datapath *dp)
 {
-       return rcu_dereference_protected(dp->table, lockdep_is_held(&dp->mutex));
+       return rcu_dereference_protected(dp->table,
+                                        lockdep_is_held(&dp->mutex));
+}
+
+static struct vport *get_vport_protected(const struct datapath *dp,
+                                        u16 port_no)
+{
+       return rcu_dereference_protected(dp->ports[port_no],
+                                        lockdep_is_held(&dp->mutex));
 }
 
 /* Must be called with rcu_read_lock or RTNL lock. */
@@ -146,7 +154,7 @@ static int dp_fill_ifinfo(struct sk_buff *skb,
 
        NLA_PUT_STRING(skb, IFLA_IFNAME, vport_get_name(port));
        NLA_PUT_U32(skb, IFLA_MASTER,
-               vport_get_ifindex(rtnl_dereference(dp->ports[ODPP_LOCAL])));
+               vport_get_ifindex(get_vport_protected(dp, ODPP_LOCAL)));
        NLA_PUT_U32(skb, IFLA_MTU, vport_get_mtu(port));
 #ifdef IFLA_OPERSTATE
        NLA_PUT_U8(skb, IFLA_OPERSTATE,
@@ -284,7 +292,7 @@ static int create_dp(int dp_idx, const char __user *devnamep)
        return 0;
 
 err_destroy_local_port:
-       dp_detach_port(dp->ports[ODPP_LOCAL]);
+       dp_detach_port(get_vport_protected(dp, ODPP_LOCAL));
 err_destroy_table:
        tbl_destroy(get_table_protected(dp), NULL);
 err_free_dp:
@@ -311,7 +319,7 @@ static void do_destroy_dp(struct datapath *dp)
 
        rcu_assign_pointer(dps[dp->dp_idx], NULL);
 
-       dp_detach_port(dp->ports[ODPP_LOCAL]);
+       dp_detach_port(get_vport_protected(dp, ODPP_LOCAL));
        tbl_destroy(get_table_protected(dp), flow_free_tbl);
 
        for (i = 0; i < DP_N_QUEUES; i++)
@@ -401,7 +409,7 @@ got_port_no:
                goto out_unlock_dp;
 
        set_internal_devs_mtu(dp);
-       dp_sysfs_add_if(dp->ports[port_no]);
+       dp_sysfs_add_if(get_vport_protected(dp, port_no));
 
        err = put_user(port_no, &portp->port);
 
@@ -452,7 +460,7 @@ static int detach_port(int dp_idx, int port_no)
        if (!dp)
                goto out_unlock_rtnl;
 
-       p = dp->ports[port_no];
+       p = get_vport_protected(dp, port_no);
        err = -ENOENT;
        if (!p)
                goto out_unlock_dp;