From f5ea9120be2e5d5c846243416cfdce01d02f5836 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 7 Aug 2009 16:17:38 +0200 Subject: 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 Signed-off-by: John W. Linville --- include/linux/nl80211.h | 17 ++++++++++++----- include/net/cfg80211.h | 12 ++++++++++++ 2 files changed, 24 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h index cb3dc6027fd9..a8d71ed43a0e 100644 --- a/include/linux/nl80211.h +++ b/include/linux/nl80211.h @@ -480,10 +480,6 @@ enum nl80211_commands { * @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 @@ enum nl80211_commands { * * @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 @@ enum nl80211_attrs { 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 @@ enum nl80211_attrs { 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 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; }; /** -- cgit v1.2.3