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, 12 insertions, 0 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 1ee30fcd6fdc..de7d116acc3d 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -372,6 +372,10 @@ struct rate_info {
  * @txrate: current unicast bitrate to this station
  * @rx_packets: packets received from this station
  * @tx_packets: packets transmitted to this station
+ * @generation: generation number for nl80211 dumps.
+ *      This number should increase every time the list of stations
+ *      changes, i.e. when a station is added or removed, so that
+ *      userspace can tell whether it got a consistent snapshot.
  */
 struct station_info {
         u32 filled;
@@ -385,6 +389,8 @@ struct station_info {
         struct rate_info txrate;
         u32 rx_packets;
         u32 tx_packets;
+
+        int generation;
 };
 
 /**
@@ -444,6 +450,10 @@ enum mpath_info_flags {
  * @flags: mesh path flags
  * @discovery_timeout: total mesh path discovery timeout, in msecs
  * @discovery_retries: mesh path discovery retries
+ * @generation: generation number for nl80211 dumps.
+ *      This number should increase every time the list of mesh paths
+ *      changes, i.e. when a station is added or removed, so that
+ *      userspace can tell whether it got a consistent snapshot.
  */
 struct mpath_info {
         u32 filled;
@@ -454,6 +464,8 @@ struct mpath_info {
         u32 discovery_timeout;
         u8 discovery_retries;
         u8 flags;
+
+        int generation;
 };
 
 /**