diff options
Diffstat (limited to 'net/mac80211/iface.c')
| -rw-r--r-- | net/mac80211/iface.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 8dc2c2188d9..00562a8b99c 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -21,6 +21,23 @@ #include "mesh.h" #include "led.h" +/** + * DOC: Interface list locking + * + * The interface list in each struct ieee80211_local is protected + * three-fold: + * + * (1) modifications may only be done under the RTNL + * (2) modifications and readers are protected against each other by + * the iflist_mtx. + * (3) modifications are done in an RCU manner so atomic readers + * can traverse the list in RCU-safe blocks. + * + * As a consequence, reads (traversals) of the list can be protected + * by either the RTNL, the iflist_mtx or RCU. + */ + + static int ieee80211_change_mtu(struct net_device *dev, int new_mtu) { int meshhdrlen; @@ -800,7 +817,9 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name, params->mesh_id_len, params->mesh_id); + mutex_lock(&local->iflist_mtx); list_add_tail_rcu(&sdata->list, &local->interfaces); + mutex_unlock(&local->iflist_mtx); if (new_dev) *new_dev = ndev; @@ -816,7 +835,10 @@ void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata) { ASSERT_RTNL(); + mutex_lock(&sdata->local->iflist_mtx); list_del_rcu(&sdata->list); + mutex_unlock(&sdata->local->iflist_mtx); + synchronize_rcu(); unregister_netdevice(sdata->dev); } @@ -832,7 +854,16 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local) ASSERT_RTNL(); list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) { + /* + * we cannot hold the iflist_mtx across unregister_netdevice, + * but we only need to hold it for list modifications to lock + * out readers since we're under the RTNL here as all other + * writers. + */ + mutex_lock(&local->iflist_mtx); list_del(&sdata->list); + mutex_unlock(&local->iflist_mtx); + unregister_netdevice(sdata->dev); } } |