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/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c
index 04b9e4d61b8e..431865a58622 100644
--- a/net/mac80211/mesh_pathtbl.c
+++ b/net/mac80211/mesh_pathtbl.c
@@ -38,6 +38,8 @@ struct mpath_node {
 static struct mesh_table *mesh_paths;
 static struct mesh_table *mpp_paths; /* Store paths for MPP&MAP */
 
+int mesh_paths_generation;
+
 /* This lock will have the grow table function as writer and add / delete nodes
  * as readers. When reading the table (i.e. doing lookups) we are well protected
  * by RCU
@@ -243,6 +245,8 @@ int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata)
 		mesh_paths->mean_chain_len * (mesh_paths->hash_mask + 1))
 		grow = 1;
 
+	mesh_paths_generation++;
+
 	spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 	read_unlock(&pathtbl_resize_lock);
 	if (grow) {
@@ -484,6 +488,7 @@ int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata)
 
 	err = -ENXIO;
 enddel:
+	mesh_paths_generation++;
 	spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 	read_unlock(&pathtbl_resize_lock);
 	return err;