nl80211: add generation number to all dumps

In order for userspace to be able to figure out whether
it obtained a consistent snapshot of data or not when
using netlink dumps, we need to have a generation number
in each dump message that indicates whether the list has
changed or not -- its value is arbitrary.

This patch adds such a number to all dumps, this needs
some mac80211 involvement to keep track of a generation
number to start with when adding/removing mesh paths or
stations.

The wiphy and netdev lists can be fully handled within
cfg80211, of course, but generation numbers need to be
stored there as well.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 1e189306560d..62e1ac00879b 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -32,6 +32,7 @@ MODULE_DESCRIPTION("wireless configuration support");
  * only read the list, and that can happen quite
  * often because we need to do it for each command */
 LIST_HEAD(cfg80211_rdev_list);
+int cfg80211_rdev_list_generation;
 
 /*
  * This is used to protect the cfg80211_rdev_list
@@ -511,6 +512,7 @@ int wiphy_register(struct wiphy *wiphy)
         wiphy_update_regulatory(wiphy, NL80211_REGDOM_SET_BY_CORE);
 
         list_add(&rdev->list, &cfg80211_rdev_list);
+        cfg80211_rdev_list_generation++;
 
         mutex_unlock(&cfg80211_mutex);
 
@@ -593,6 +595,7 @@ void wiphy_unregister(struct wiphy *wiphy)
         reg_device_remove(wiphy);
 
         list_del(&rdev->list);
+        cfg80211_rdev_list_generation++;
         device_del(&rdev->wiphy.dev);
         debugfs_remove(rdev->wiphy.debugfsdir);
 
@@ -653,6 +656,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
                 spin_lock_init(&wdev->event_lock);
                 mutex_lock(&rdev->devlist_mtx);
                 list_add(&wdev->list, &rdev->netdev_list);
+                rdev->devlist_generation++;
                 /* can only change netns with wiphy */
                 dev->features |= NETIF_F_NETNS_LOCAL;
 
@@ -733,6 +737,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
                 if (!list_empty(&wdev->list)) {
                         sysfs_remove_link(&dev->dev.kobj, "phy80211");
                         list_del_init(&wdev->list);
+                        rdev->devlist_generation++;
                         mutex_destroy(&wdev->mtx);
 #ifdef CONFIG_WIRELESS_EXT
                         kfree(wdev->wext.keys);