diff options
author | Johannes Berg <johannes@sipsolutions.net> | 2009-01-23 21:54:03 (GMT) |
---|---|---|
committer | John W. Linville <linville@tuxdriver.com> | 2009-01-29 21:01:45 (GMT) |
commit | c771c9d8da1e8292ef8bf7fd4ce135dacc650130 (patch) | |
tree | 79b259a6b0396cbecf9e775c7ba5a80e2c4d94c9 /net/mac80211/iface.c | |
parent | 506d03f97d10e54fd27c58c872a98242326d6419 (diff) | |
download | linux-fsl-qoriq-c771c9d8da1e8292ef8bf7fd4ce135dacc650130.tar.xz |
mac80211: add interface list lock
Using only the RTNL has a number of problems, most notably that
ieee80211_iterate_active_interfaces() and other interface list
traversals cannot be done from the internal workqueue because it
needs to be flushed under the RTNL.
This patch introduces a new mutex that protects the interface list
against modifications. A more detailed explanation is part of the
code change.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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 8dc2c21..00562a8 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); } } |