From 992e68bf2eb9f3319f098560b8d4a03aa52fd7b8 Mon Sep 17 00:00:00 2001 From: Soumik Das Date: Sun, 20 May 2012 15:31:13 +0530 Subject: [PATCH] mac80211: Fix race in checking AP status by sending null frame mac80211 tries to verify the existence of the current AP by probing or sending a NULL frame in function ieee80211_mgd_probe_ap_send. It 1st sends a null frame to the AP, increments probe_send_count and waits for the ACK to the NULL frame for a finite duration of time. At times, it happens that by the time mac80211 gets to increment probe_send_count, the ACK for the NULL frame transmitted has already been processed. This leads to a race condition where mac80211 times out waiting for the ACK for the NULL frame causing unnecessary disconnection with the AP. Signed-off-by: Soumik Das Signed-off-by: John W. Linville --- net/mac80211/mlme.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index b3b3c264ff66..04c306308987 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -1522,6 +1522,8 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata) * anymore. The timeout will be reset if the frame is ACKed by * the AP. */ + ifmgd->probe_send_count++; + if (sdata->local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) { ifmgd->nullfunc_failed = false; ieee80211_send_nullfunc(sdata->local, sdata, 0); @@ -1538,7 +1540,6 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata) 0, (u32) -1, true, false); } - ifmgd->probe_send_count++; ifmgd->probe_timeout = jiffies + msecs_to_jiffies(probe_wait_ms); run_again(ifmgd, ifmgd->probe_timeout); if (sdata->local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) -- GitLab