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>
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index cb3dc60..a8d71ed 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -480,10 +480,6 @@
* @NL80211_ATTR_SCAN_FREQUENCIES: nested attribute with frequencies (in MHz)
* @NL80211_ATTR_SCAN_SSIDS: nested attribute with SSIDs, leave out for passive
* scanning and include a zero-length SSID (wildcard) for wildcard scan
- * @NL80211_ATTR_SCAN_GENERATION: the scan generation increases whenever the
- * scan result list changes (BSS expired or added) so that applications
- * can verify that they got a single, consistent snapshot (when all dump
- * messages carried the same generation number)
* @NL80211_ATTR_BSS: scan result BSS
*
* @NL80211_ATTR_REG_INITIATOR: indicates who requested the regulatory domain
@@ -580,6 +576,14 @@
*
* @NL80211_ATTR_PID: Process ID of a network namespace.
*
+ * @NL80211_ATTR_GENERATION: Used to indicate consistent snapshots for
+ * dumps. This number increases whenever the object list being
+ * dumped changes, and as such userspace can verify that it has
+ * obtained a complete and consistent snapshot by verifying that
+ * all dump messages contain the same generation number. If it
+ * changed then the list changed and the dump should be repeated
+ * completely from scratch.
+ *
* @NL80211_ATTR_MAX: highest attribute number currently defined
* @__NL80211_ATTR_AFTER_LAST: internal use
*/
@@ -651,7 +655,7 @@
NL80211_ATTR_SCAN_FREQUENCIES,
NL80211_ATTR_SCAN_SSIDS,
- NL80211_ATTR_SCAN_GENERATION,
+ NL80211_ATTR_GENERATION, /* replaces old SCAN_GENERATION */
NL80211_ATTR_BSS,
NL80211_ATTR_REG_INITIATOR,
@@ -716,6 +720,9 @@
NL80211_ATTR_MAX = __NL80211_ATTR_AFTER_LAST - 1
};
+/* source-level API compatibility */
+#define NL80211_ATTR_SCAN_GENERATION NL80211_ATTR_GENERATION
+
/*
* Allow user space programs to use #ifdef on new attributes by defining them
* here