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nl80211: add generation number to all dumps

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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>
This commit is contained in:
Johannes Berg
2009-08-07 16:17:38 +02:00
committed by John W. Linville
parent f401a6f7ed
commit f5ea9120be
11 changed files with 67 additions and 15 deletions
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17
include/linux/nl80211.h
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@ -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