From c6d14c84566d6b70ad9dc1618db0dec87cca9300 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 4 Nov 2009 05:43:23 -0800 Subject: net: Introduce for_each_netdev_rcu() iterator Adds RCU management to the list of netdevices. Convert some for_each_netdev() users to RCU version, if it can avoid read_lock-ing dev_base_lock Ie: read_lock(&dev_base_loack); for_each_netdev(net, dev) some_action(); read_unlock(&dev_base_lock); becomes : rcu_read_lock(); for_each_netdev_rcu(net, dev) some_action(); rcu_read_unlock(); Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/dev.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index 76a1502efe67..bf629ac08b87 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -175,7 +175,7 @@ static struct list_head ptype_all __read_mostly; /* Taps */ * The @dev_base_head list is protected by @dev_base_lock and the rtnl * semaphore. * - * Pure readers hold dev_base_lock for reading. + * Pure readers hold dev_base_lock for reading, or rcu_read_lock() * * Writers must hold the rtnl semaphore while they loop through the * dev_base_head list, and hold dev_base_lock for writing when they do the @@ -212,7 +212,7 @@ static int list_netdevice(struct net_device *dev) ASSERT_RTNL(); write_lock_bh(&dev_base_lock); - list_add_tail(&dev->dev_list, &net->dev_base_head); + list_add_tail_rcu(&dev->dev_list, &net->dev_base_head); hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name)); hlist_add_head_rcu(&dev->index_hlist, dev_index_hash(net, dev->ifindex)); @@ -229,7 +229,7 @@ static void unlist_netdevice(struct net_device *dev) /* Unlink dev from the device chain */ write_lock_bh(&dev_base_lock); - list_del(&dev->dev_list); + list_del_rcu(&dev->dev_list); hlist_del_rcu(&dev->name_hlist); hlist_del_rcu(&dev->index_hlist); write_unlock_bh(&dev_base_lock); @@ -799,15 +799,15 @@ struct net_device *dev_get_by_flags(struct net *net, unsigned short if_flags, struct net_device *dev, *ret; ret = NULL; - read_lock(&dev_base_lock); - for_each_netdev(net, dev) { + rcu_read_lock(); + for_each_netdev_rcu(net, dev) { if (((dev->flags ^ if_flags) & mask) == 0) { dev_hold(dev); ret = dev; break; } } - read_unlock(&dev_base_lock); + rcu_read_unlock(); return ret; } EXPORT_SYMBOL(dev_get_by_flags); @@ -3077,18 +3077,18 @@ static int dev_ifconf(struct net *net, char __user *arg) * in detail. */ void *dev_seq_start(struct seq_file *seq, loff_t *pos) - __acquires(dev_base_lock) + __acquires(RCU) { struct net *net = seq_file_net(seq); loff_t off; struct net_device *dev; - read_lock(&dev_base_lock); + rcu_read_lock(); if (!*pos) return SEQ_START_TOKEN; off = 1; - for_each_netdev(net, dev) + for_each_netdev_rcu(net, dev) if (off++ == *pos) return dev; @@ -3097,16 +3097,18 @@ void *dev_seq_start(struct seq_file *seq, loff_t *pos) void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos) { - struct net *net = seq_file_net(seq); + struct net_device *dev = (v == SEQ_START_TOKEN) ? + first_net_device(seq_file_net(seq)) : + next_net_device((struct net_device *)v); + ++*pos; - return v == SEQ_START_TOKEN ? - first_net_device(net) : next_net_device((struct net_device *)v); + return rcu_dereference(dev); } void dev_seq_stop(struct seq_file *seq, void *v) - __releases(dev_base_lock) + __releases(RCU) { - read_unlock(&dev_base_lock); + rcu_read_unlock(); } static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev) -- cgit v1.2.3-59-g8ed1b