net: listening_hash get a spinlock per bucket
This patch prepares RCU migration of listening_hash table for
TCP/DCCP protocols.
listening_hash table being small (32 slots per protocol), we add
a spinlock for each slot, instead of a single rwlock for whole table.
This should reduce hold time of readers, and writers concurrency.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 4818960..62d2dd0d 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -99,6 +99,11 @@
struct hlist_head chain;
};
+struct inet_listen_hashbucket {
+ spinlock_t lock;
+ struct hlist_head head;
+};
+
/* This is for listening sockets, thus all sockets which possess wildcards. */
#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
@@ -123,22 +128,21 @@
unsigned int bhash_size;
/* Note : 4 bytes padding on 64 bit arches */
- /* All sockets in TCP_LISTEN state will be in here. This is the only
- * table where wildcard'd TCP sockets can exist. Hash function here
- * is just local port number.
- */
- struct hlist_head listening_hash[INET_LHTABLE_SIZE];
+ struct kmem_cache *bind_bucket_cachep;
/* All the above members are written once at bootup and
* never written again _or_ are predominantly read-access.
*
* Now align to a new cache line as all the following members
- * are often dirty.
+ * might be often dirty.
*/
- rwlock_t lhash_lock ____cacheline_aligned;
- atomic_t lhash_users;
- wait_queue_head_t lhash_wait;
- struct kmem_cache *bind_bucket_cachep;
+ /* All sockets in TCP_LISTEN state will be in here. This is the only
+ * table where wildcard'd TCP sockets can exist. Hash function here
+ * is just local port number.
+ */
+ struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE]
+ ____cacheline_aligned_in_smp;
+
};
static inline struct inet_ehash_bucket *inet_ehash_bucket(
@@ -236,26 +240,7 @@
extern void inet_put_port(struct sock *sk);
-extern void inet_listen_wlock(struct inet_hashinfo *hashinfo);
-
-/*
- * - We may sleep inside this lock.
- * - If sleeping is not required (or called from BH),
- * use plain read_(un)lock(&inet_hashinfo.lhash_lock).
- */
-static inline void inet_listen_lock(struct inet_hashinfo *hashinfo)
-{
- /* read_lock synchronizes to candidates to writers */
- read_lock(&hashinfo->lhash_lock);
- atomic_inc(&hashinfo->lhash_users);
- read_unlock(&hashinfo->lhash_lock);
-}
-
-static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo)
-{
- if (atomic_dec_and_test(&hashinfo->lhash_users))
- wake_up(&hashinfo->lhash_wait);
-}
+void inet_hashinfo_init(struct inet_hashinfo *h);
extern void __inet_hash_nolisten(struct sock *sk);
extern void inet_hash(struct sock *sk);
