diff options
| -rw-r--r-- | net/can/af_can.c | 52 |
1 files changed, 32 insertions, 20 deletions
diff --git a/net/can/af_can.c b/net/can/af_can.c index 733d66f1b05..a8dcaa49675 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -85,7 +85,7 @@ static struct kmem_cache *rcv_cache __read_mostly; /* table of registered CAN protocols */ static struct can_proto *proto_tab[CAN_NPROTO] __read_mostly; -static DEFINE_SPINLOCK(proto_tab_lock); +static DEFINE_MUTEX(proto_tab_lock); struct timer_list can_stattimer; /* timer for statistics update */ struct s_stats can_stats; /* packet statistics */ @@ -115,6 +115,19 @@ static void can_sock_destruct(struct sock *sk) skb_queue_purge(&sk->sk_receive_queue); } +static struct can_proto *can_try_module_get(int protocol) +{ + struct can_proto *cp; + + rcu_read_lock(); + cp = rcu_dereference(proto_tab[protocol]); + if (cp && !try_module_get(cp->prot->owner)) + cp = NULL; + rcu_read_unlock(); + + return cp; +} + static int can_create(struct net *net, struct socket *sock, int protocol, int kern) { @@ -130,9 +143,12 @@ static int can_create(struct net *net, struct socket *sock, int protocol, if (!net_eq(net, &init_net)) return -EAFNOSUPPORT; + cp = can_try_module_get(protocol); + #ifdef CONFIG_MODULES - /* try to load protocol module kernel is modular */ - if (!proto_tab[protocol]) { + if (!cp) { + /* try to load protocol module if kernel is modular */ + err = request_module("can-proto-%d", protocol); /* @@ -143,22 +159,18 @@ static int can_create(struct net *net, struct socket *sock, int protocol, if (err && printk_ratelimit()) printk(KERN_ERR "can: request_module " "(can-proto-%d) failed.\n", protocol); + + cp = can_try_module_get(protocol); } #endif - spin_lock(&proto_tab_lock); - cp = proto_tab[protocol]; - if (cp && !try_module_get(cp->prot->owner)) - cp = NULL; - spin_unlock(&proto_tab_lock); - /* check for available protocol and correct usage */ if (!cp) return -EPROTONOSUPPORT; if (cp->type != sock->type) { - err = -EPROTONOSUPPORT; + err = -EPROTOTYPE; goto errout; } @@ -694,15 +706,16 @@ int can_proto_register(struct can_proto *cp) if (err < 0) return err; - spin_lock(&proto_tab_lock); + mutex_lock(&proto_tab_lock); + if (proto_tab[proto]) { printk(KERN_ERR "can: protocol %d already registered\n", proto); err = -EBUSY; } else - proto_tab[proto] = cp; + rcu_assign_pointer(proto_tab[proto], cp); - spin_unlock(&proto_tab_lock); + mutex_unlock(&proto_tab_lock); if (err < 0) proto_unregister(cp->prot); @@ -719,13 +732,12 @@ void can_proto_unregister(struct can_proto *cp) { int proto = cp->protocol; - spin_lock(&proto_tab_lock); - if (!proto_tab[proto]) { - printk(KERN_ERR "BUG: can: protocol %d is not registered\n", - proto); - } - proto_tab[proto] = NULL; - spin_unlock(&proto_tab_lock); + mutex_lock(&proto_tab_lock); + BUG_ON(proto_tab[proto] != cp); + rcu_assign_pointer(proto_tab[proto], NULL); + mutex_unlock(&proto_tab_lock); + + synchronize_rcu(); proto_unregister(cp->prot); } |