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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Yibo Zhao <yiboz@codeaurora.org>,
	Zhi Chen <zhichen@codeaurora.org>,
	Johannes Berg <johannes.berg@intel.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 17/21] mac80211: only warn once on chanctx_conf being NULL
Date: Wed, 26 Jun 2019 20:41:17 -0400
Message-ID: <20190627004122.21671-17-sashal@kernel.org> (raw)
In-Reply-To: <20190627004122.21671-1-sashal@kernel.org>

From: Yibo Zhao <yiboz@codeaurora.org>

[ 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 <zhichen@codeaurora.org>
Signed-off-by: Yibo Zhao <yiboz@codeaurora.org>
[johannes: add note, change subject]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 8a690ebd7374..6708de10a3e5 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1403,7 +1403,7 @@ 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


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190627004122.21671-1-sashal@kernel.org>
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 02/21] samples, bpf: fix to change the buffer size for read() Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 04/21] mac80211: mesh: fix RCU warning Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 05/21] mac80211: free peer keys before vif down in mesh Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 06/21] mwifiex: Fix possible buffer overflows at parsing bss descriptor Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 07/21] mwifiex: Abort at too short BSS descriptor element Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 08/21] netfilter: ipv6: nf_defrag: fix leakage of unqueued fragments Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 09/21] netfilter: ipv6: nf_defrag: accept duplicate fragments again Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 10/21] dt-bindings: can: mcp251x: add mcp25625 support Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 11/21] can: mcp251x: add support for mcp25625 Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 14/21] mlxsw: spectrum: Disallow prio-tagged packets when PVID is removed Sasha Levin
2019-06-27  0:41 ` Sasha Levin [this message]
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 19/21] bnx2x: Check if transceiver implements DDM before access Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 20/21] ip6_tunnel: allow not to count pkts on tstats by passing dev as NULL Sasha Levin
2019-06-27  0:41 ` [PATCH AUTOSEL 4.9 21/21] net :sunrpc :clnt :Fix xps refcount imbalance on the error path Sasha Levin

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