From 5caea4ea7088e80ac5410d04660346094608b909 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 20 Nov 2008 00:40:07 -0800 Subject: 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 Signed-off-by: David S. Miller --- include/net/inet_hashtables.h | 45 +++++++++++++++---------------------------- 1 file changed, 15 insertions(+), 30 deletions(-) (limited to 'include/net/inet_hashtables.h') diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 48189604511..62d2dd0d786 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -99,6 +99,11 @@ struct inet_bind_hashbucket { 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 @@ struct inet_hashinfo { 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. + */ + /* 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. */ - rwlock_t lhash_lock ____cacheline_aligned; - atomic_t lhash_users; - wait_queue_head_t lhash_wait; - struct kmem_cache *bind_bucket_cachep; + 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_inherit_port(struct sock *sk, struct sock *child); 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); -- cgit v1.2.3