nl/mac80211: allow zero plink timeout to disable STA expiration

Both wpa_supplicant and mac80211 have and inactivity timer. By default
wpa_supplicant will be timed out in 5 minutes and mac80211's it is 30
minutes. If wpa_supplicant uses a longer timer than mac80211, it will
get unexpected disconnection by mac80211.

Using 0xffffffff instead as the configured value could solve this w/o
changing the code, but due to integer overflow in the expression used
this doesn't work. The expression is:

(current jiffies) > (frame Rx jiffies + NL80211_MESHCONF_PLINK_TIMEOUT * 250)

On 32bit system, the right side would overflow and be a very small
value if NL80211_MESHCONF_PLINK_TIMEOUT is sufficiently large,
causing unexpectedly early disconnections.

Instead allow disabling the inactivity timer to avoid this situation,
by passing the (previously invalid and useless) value 0.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
[reword/rewrap commit log]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 68b294e83944..2dcf9bba317c 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -3092,7 +3092,8 @@ enum nl80211_mesh_power_mode {
  *
  * @NL80211_MESHCONF_PLINK_TIMEOUT: If no tx activity is seen from a STA we've
  *      established peering with for longer than this time (in seconds), then
- *      remove it from the STA's list of peers.  Default is 30 minutes.
+ *      remove it from the STA's list of peers. You may set this to 0 to disable
+ *      the removal of the STA. Default is 30 minutes.
  *
  * @__NL80211_MESHCONF_ATTR_AFTER_LAST: internal use
  */