lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

mac80211: add interface list lock

Browse Source 
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>
This commit is contained in:
Johannes Berg
2009-01-23 22:54:03 +01:00
committed by John W. Linville
parent 506d03f97d
commit c771c9d8da
5 changed files with 40 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
net/mac80211/iface.c
View File

@@ -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);
}
}