net neigh: RCU conversion of neigh hash table

David

This is the first step for RCU conversion of neigh code.

Next patches will convert hash_buckets[] and "struct neighbour" to RCU
protected objects.

Thanks

[PATCH net-next] net neigh: RCU conversion of neigh hash table

Instead of storing hash_buckets, hash_mask and hash_rnd in "struct
neigh_table", a new structure is defined :

struct neigh_hash_table {
       struct neighbour        **hash_buckets;
       unsigned int            hash_mask;
       __u32                   hash_rnd;
       struct rcu_head         rcu;
};

And "struct neigh_table" has an RCU protected pointer to such a
neigh_hash_table.

This means the signature of (*hash)() function changed: We need to add a
third parameter with the actual hash_rnd value, since this is not
anymore a neigh_table field.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 4 deletions

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 7d08fd1062f0..37845dae6488 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -138,13 +138,22 @@ struct pneigh_entry {
  *      neighbour table manipulation
  */
 
+struct neigh_hash_table {
+        struct neighbour        **hash_buckets;
+        unsigned int            hash_mask;
+        __u32                   hash_rnd;
+        struct rcu_head         rcu;
+};
+
 
 struct neigh_table {
         struct neigh_table      *next;
         int                     family;
         int                     entry_size;
         int                     key_len;
-        __u32                   (*hash)(const void *pkey, const struct net_device *);
+        __u32                   (*hash)(const void *pkey,
+                                        const struct net_device *dev,
+                                        __u32 hash_rnd);
         int                     (*constructor)(struct neighbour *);
         int                     (*pconstructor)(struct pneigh_entry *);
         void                    (*pdestructor)(struct pneigh_entry *);
@@ -165,9 +174,7 @@ struct neigh_table {
         unsigned long           last_rand;
         struct kmem_cache       *kmem_cachep;
         struct neigh_statistics __percpu *stats;
-        struct neighbour        **hash_buckets;
-        unsigned int            hash_mask;
-        __u32                   hash_rnd;
+        struct neigh_hash_table __rcu *nht;
         struct pneigh_entry     **phash_buckets;
 };
 
@@ -237,6 +244,7 @@ extern void pneigh_for_each(struct neigh_table *tbl, void (*cb)(struct pneigh_en
 struct neigh_seq_state {
         struct seq_net_private p;
         struct neigh_table *tbl;
+        struct neigh_hash_table *nht;
         void *(*neigh_sub_iter)(struct neigh_seq_state *state,
                                 struct neighbour *n, loff_t *pos);
         unsigned int bucket;