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 1e189306560..62e1ac00879 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);