From 4efb3c121b3c9b99f78af1c6fa7cc837752e92f9 Mon Sep 17 00:00:00 2001 From: Yibo Zhao Date: Fri, 14 Jun 2019 19:01:52 +0800 Subject: [PATCH] mac80211: only warn once on chanctx_conf being NULL [ Upstream commit 563572340173865a9a356e6bb02579e6998a876d ] In multiple SSID cases, it takes time to prepare every AP interface to be ready in initializing phase. If a sta already knows everything it needs to join one of the APs and sends authentication to the AP which is not fully prepared at this point of time, AP's channel context could be NULL. As a result, warning message occurs. Even worse, if the AP is under attack via tools such as MDK3 and massive authentication requests are received in a very short time, console will be hung due to kernel warning messages. WARN_ON_ONCE() could be a better way for indicating warning messages without duplicate messages to flood the console. Johannes: We still need to address the underlying problem, but we don't really have a good handle on it yet. Suppress the worst side-effects for now. Signed-off-by: Zhi Chen Signed-off-by: Yibo Zhao [johannes: add note, change subject] Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- net/mac80211/ieee80211_i.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index a133acb43eb1..0e209a88d88a 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1405,7 +1405,7 @@ ieee80211_get_sband(struct ieee80211_sub_if_data *sdata) rcu_read_lock(); chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); - if (WARN_ON(!chanctx_conf)) { + if (WARN_ON_ONCE(!chanctx_conf)) { rcu_read_unlock(); return NULL; } -- 2.20.1