Merge branch 'locking'

[openvswitch] / datapath / datapath.c

diff --git a/datapath/datapath.c b/datapath/datapath.c
index f81388d6156a7c6f283d0c46fdac1d9cc4ec602c..a303f5008282fb6885b7aecb6fac4053bf48caf7 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -28,6 +28,7 @@
 #include <linux/netfilter_bridge.h>
 #include <linux/inetdevice.h>
 #include <linux/list.h>
+#include <linux/rculist.h>
 
 #include "openflow-netlink.h"
 #include "datapath.h"
@@ -63,15 +64,16 @@ static struct genl_multicast_group mc_group;
 /* It's hard to imagine wanting more than one datapath, but... */
 #define DP_MAX 32
 
-/* datapaths.  Protected on the read side by rcu_read_lock, on the write side
- * by dp_mutex.
+/* Datapaths.  Protected on the read side by rcu_read_lock, on the write side
+ * by dp_mutex.  dp_mutex is almost completely redundant with genl_mutex
+ * maintained by the Generic Netlink code, but the timeout path needs mutual
+ * exclusion too.
  *
  * It is safe to access the datapath and net_bridge_port structures with just
- * the dp_mutex, but to access the chain you need to take the rcu_read_lock
- * also (because dp_mutex doesn't prevent flows from being destroyed).
+ * dp_mutex.
  */
 static struct datapath *dps[DP_MAX];
-static DEFINE_MUTEX(dp_mutex);
+DEFINE_MUTEX(dp_mutex);
 
 static int dp_maint_func(void *data);
 static int send_port_status(struct net_bridge_port *p, uint8_t status);
@@ -241,9 +243,7 @@ uint64_t gen_datapath_id(uint16_t dp_idx)
 }
 
 /* Creates a new datapath numbered 'dp_idx'.  Returns 0 for success or a
- * negative error code.
- *
- * Not called with any locks. */
+ * negative error code. */
 static int new_dp(int dp_idx)
 {
        struct datapath *dp;
@@ -255,9 +255,8 @@ static int new_dp(int dp_idx)
        if (!try_module_get(THIS_MODULE))
                return -ENODEV;
 
-       mutex_lock(&dp_mutex);
-       dp = rcu_dereference(dps[dp_idx]);
-       if (dp != NULL) {
+       /* Exit early if a datapath with that number already exists. */
+       if (dps[dp_idx]) {
                err = -EEXIST;
                goto err_unlock;
        }
@@ -292,8 +291,7 @@ static int new_dp(int dp_idx)
        if (IS_ERR(dp->dp_task))
                goto err_destroy_chain;
 
-       rcu_assign_pointer(dps[dp_idx], dp);
-       mutex_unlock(&dp_mutex);
+       dps[dp_idx] = dp;
 
        return 0;
 
@@ -306,12 +304,11 @@ err_destroy_dp_dev:
 err_free_dp:
        kfree(dp);
 err_unlock:
-       mutex_unlock(&dp_mutex);
        module_put(THIS_MODULE);
                return err;
 }
 
-/* Find and return a free port number under 'dp'.  Called under dp_mutex. */
+/* Find and return a free port number under 'dp'. */
 static int find_portno(struct datapath *dp)
 {
        int i;
@@ -349,7 +346,6 @@ static struct net_bridge_port *new_nbp(struct datapath *dp,
        return p;
 }
 
-/* Called with dp_mutex. */
 int add_switch_port(struct datapath *dp, struct net_device *dev)
 {
        struct net_bridge_port *p;
@@ -373,8 +369,7 @@ int add_switch_port(struct datapath *dp, struct net_device *dev)
        return 0;
 }
 
-/* Delete 'p' from switch.
- * Called with dp_mutex. */
+/* Delete 'p' from switch. */
 static int del_switch_port(struct net_bridge_port *p)
 {
        /* First drop references to device. */
@@ -398,7 +393,6 @@ static int del_switch_port(struct net_bridge_port *p)
        return 0;
 }
 
-/* Called with dp_mutex. */
 static void del_dp(struct datapath *dp)
 {
        struct net_bridge_port *p, *n;
@@ -466,8 +460,6 @@ static int dp_frame_hook(struct net_bridge_port *p, struct sk_buff **pskb)
 }
 #else
 /* NB: This has only been tested on 2.4.35 */
-
-/* Called without any locks (?) */
 static void dp_frame_hook(struct sk_buff *skb)
 {
        struct net_bridge_port *p = skb->dev->br_port;
@@ -881,7 +873,6 @@ static int dp_genl_del(struct sk_buff *skb, struct genl_info *info)
        if (!info->attrs[DP_GENL_A_DP_IDX])
                return -EINVAL;
 
-       mutex_lock(&dp_mutex);
        dp = dp_get(nla_get_u32((info->attrs[DP_GENL_A_DP_IDX])));
        if (!dp)
                err = -ENOENT;
@@ -889,7 +880,6 @@ static int dp_genl_del(struct sk_buff *skb, struct genl_info *info)
                del_dp(dp);
                err = 0;
        }
-       mutex_unlock(&dp_mutex);
        return err;
 }
 
@@ -973,7 +963,6 @@ static int dp_genl_add_del_port(struct sk_buff *skb, struct genl_info *info)
                return -EINVAL;
 
        /* Get datapath. */
-       mutex_lock(&dp_mutex);
        dp = dp_get(nla_get_u32(info->attrs[DP_GENL_A_DP_IDX]));
        if (!dp) {
                err = -ENOENT;
@@ -1002,7 +991,6 @@ static int dp_genl_add_del_port(struct sk_buff *skb, struct genl_info *info)
 out_put:
        dev_put(port);
 out:
-       mutex_unlock(&dp_mutex);
        return err;
 }
 
@@ -1028,6 +1016,7 @@ static int dp_genl_openflow(struct sk_buff *skb, struct genl_info *info)
        struct datapath *dp;
        struct ofp_header *oh;
        struct sender sender;
+       int err;
 
        if (!info->attrs[DP_GENL_A_DP_IDX] || !va)
                return -EINVAL;
@@ -1043,8 +1032,12 @@ static int dp_genl_openflow(struct sk_buff *skb, struct genl_info *info)
        sender.xid = oh->xid;
        sender.pid = info->snd_pid;
        sender.seq = info->snd_seq;
-       return fwd_control_input(dp->chain, &sender,
-                                nla_data(va), nla_len(va));
+
+       mutex_lock(&dp_mutex);
+       err = fwd_control_input(dp->chain, &sender,
+                               nla_data(va), nla_len(va));
+       mutex_unlock(&dp_mutex);
+       return err;
 }
 
 static struct nla_policy dp_genl_openflow_policy[DP_GENL_A_MAX + 1] = {