From: James Chapman Date: Fri, 2 Apr 2010 06:19:16 +0000 (+0000) Subject: l2tp: Convert rwlock to RCU X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e02d494d2c60746ee6583132904ac1791f5bc9a6;p=linux-beck.git l2tp: Convert rwlock to RCU Reader/write locks are discouraged because they are slower than spin locks. So this patch converts the rwlocks used in the per_net structs to rcu. Signed-off-by: James Chapman Signed-off-by: David S. Miller --- diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index fbd1f2119fe9..473cf2d63905 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -105,9 +106,9 @@ static atomic_t l2tp_session_count; static unsigned int l2tp_net_id; struct l2tp_net { struct list_head l2tp_tunnel_list; - rwlock_t l2tp_tunnel_list_lock; + spinlock_t l2tp_tunnel_list_lock; struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; - rwlock_t l2tp_session_hlist_lock; + spinlock_t l2tp_session_hlist_lock; }; static inline struct l2tp_net *l2tp_pernet(struct net *net) @@ -139,14 +140,14 @@ static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id) struct l2tp_session *session; struct hlist_node *walk; - read_lock_bh(&pn->l2tp_session_hlist_lock); - hlist_for_each_entry(session, walk, session_list, global_hlist) { + rcu_read_lock_bh(); + hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) { if (session->session_id == session_id) { - read_unlock_bh(&pn->l2tp_session_hlist_lock); + rcu_read_unlock_bh(); return session; } } - read_unlock_bh(&pn->l2tp_session_hlist_lock); + rcu_read_unlock_bh(); return NULL; } @@ -225,17 +226,17 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname) struct hlist_node *walk; struct l2tp_session *session; - read_lock_bh(&pn->l2tp_session_hlist_lock); + rcu_read_lock_bh(); for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { - hlist_for_each_entry(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) { + hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) { if (!strcmp(session->ifname, ifname)) { - read_unlock_bh(&pn->l2tp_session_hlist_lock); + rcu_read_unlock_bh(); return session; } } } - read_unlock_bh(&pn->l2tp_session_hlist_lock); + rcu_read_unlock_bh(); return NULL; } @@ -248,14 +249,14 @@ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id) struct l2tp_tunnel *tunnel; struct l2tp_net *pn = l2tp_pernet(net); - read_lock_bh(&pn->l2tp_tunnel_list_lock); - list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) { + rcu_read_lock_bh(); + list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { if (tunnel->tunnel_id == tunnel_id) { - read_unlock_bh(&pn->l2tp_tunnel_list_lock); + rcu_read_unlock_bh(); return tunnel; } } - read_unlock_bh(&pn->l2tp_tunnel_list_lock); + rcu_read_unlock_bh(); return NULL; } @@ -267,15 +268,15 @@ struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth) struct l2tp_tunnel *tunnel; int count = 0; - read_lock_bh(&pn->l2tp_tunnel_list_lock); - list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) { + rcu_read_lock_bh(); + list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { if (++count > nth) { - read_unlock_bh(&pn->l2tp_tunnel_list_lock); + rcu_read_unlock_bh(); return tunnel; } } - read_unlock_bh(&pn->l2tp_tunnel_list_lock); + rcu_read_unlock_bh(); return NULL; } @@ -1167,9 +1168,10 @@ again: if (tunnel->version != L2TP_HDR_VER_2) { struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); - write_lock_bh(&pn->l2tp_session_hlist_lock); - hlist_del_init(&session->global_hlist); - write_unlock_bh(&pn->l2tp_session_hlist_lock); + spin_lock_bh(&pn->l2tp_session_hlist_lock); + hlist_del_init_rcu(&session->global_hlist); + spin_unlock_bh(&pn->l2tp_session_hlist_lock); + synchronize_rcu(); } if (session->session_close != NULL) @@ -1206,9 +1208,10 @@ void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) "%s: free...\n", tunnel->name); /* Remove from tunnel list */ - write_lock_bh(&pn->l2tp_tunnel_list_lock); - list_del_init(&tunnel->list); - write_unlock_bh(&pn->l2tp_tunnel_list_lock); + spin_lock_bh(&pn->l2tp_tunnel_list_lock); + list_del_rcu(&tunnel->list); + spin_unlock_bh(&pn->l2tp_tunnel_list_lock); + synchronize_rcu(); atomic_dec(&l2tp_tunnel_count); kfree(tunnel); @@ -1310,9 +1313,10 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 /* Add tunnel to our list */ INIT_LIST_HEAD(&tunnel->list); - write_lock_bh(&pn->l2tp_tunnel_list_lock); - list_add(&tunnel->list, &pn->l2tp_tunnel_list); - write_unlock_bh(&pn->l2tp_tunnel_list_lock); + spin_lock_bh(&pn->l2tp_tunnel_list_lock); + list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); + spin_unlock_bh(&pn->l2tp_tunnel_list_lock); + synchronize_rcu(); atomic_inc(&l2tp_tunnel_count); /* Bump the reference count. The tunnel context is deleted @@ -1370,9 +1374,10 @@ void l2tp_session_free(struct l2tp_session *session) if (tunnel->version != L2TP_HDR_VER_2) { struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); - write_lock_bh(&pn->l2tp_session_hlist_lock); - hlist_del_init(&session->global_hlist); - write_unlock_bh(&pn->l2tp_session_hlist_lock); + spin_lock_bh(&pn->l2tp_session_hlist_lock); + hlist_del_init_rcu(&session->global_hlist); + spin_unlock_bh(&pn->l2tp_session_hlist_lock); + synchronize_rcu(); } if (session->session_id != 0) @@ -1494,10 +1499,11 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn if (tunnel->version != L2TP_HDR_VER_2) { struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); - write_lock_bh(&pn->l2tp_session_hlist_lock); - hlist_add_head(&session->global_hlist, - l2tp_session_id_hash_2(pn, session_id)); - write_unlock_bh(&pn->l2tp_session_hlist_lock); + spin_lock_bh(&pn->l2tp_session_hlist_lock); + hlist_add_head_rcu(&session->global_hlist, + l2tp_session_id_hash_2(pn, session_id)); + spin_unlock_bh(&pn->l2tp_session_hlist_lock); + synchronize_rcu(); } /* Ignore management session in session count value */ @@ -1524,12 +1530,12 @@ static __net_init int l2tp_init_net(struct net *net) return -ENOMEM; INIT_LIST_HEAD(&pn->l2tp_tunnel_list); - rwlock_init(&pn->l2tp_tunnel_list_lock); + spin_lock_init(&pn->l2tp_tunnel_list_lock); for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); - rwlock_init(&pn->l2tp_session_hlist_lock); + spin_lock_init(&pn->l2tp_session_hlist_lock); err = net_assign_generic(net, l2tp_net_id, pn); if (err)