Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Karthikeyan Kathirvel <kathirve@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 04/10] mac80211: choose first enabled channel for monitor
Date:   Mon, 29 Mar 2021 18:23:55 -0400
Message-Id: <20210329222401.2383930-4-sashal@kernel.org>
In-Reply-To: <20210329222401.2383930-1-sashal@kernel.org>
References: <20210329222401.2383930-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Karthikeyan Kathirvel <kathirve@codeaurora.org>

[ Upstream commit 041c881a0ba8a75f71118bd9766b78f04beed469 ]

Even if the first channel from sband channel list is invalid
or disabled mac80211 ends up choosing it as the default channel
for monitor interfaces, making them not usable.

Fix this by assigning the first available valid or enabled
channel instead.

Signed-off-by: Karthikeyan Kathirvel <kathirve@codeaurora.org>
Link: https://lore.kernel.org/r/1615440547-7661-1-git-send-email-kathirve@codeaurora.org
[reword commit message, comment, code cleanups]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mac80211/main.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index e3bbfb20ae82..f31fd21d59ba 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -906,8 +906,19 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 			continue;
 
 		if (!dflt_chandef.chan) {
+			/*
+			 * Assign the first enabled channel to dflt_chandef
+			 * from the list of channels
+			 */
+			for (i = 0; i < sband->n_channels; i++)
+				if (!(sband->channels[i].flags &
+						IEEE80211_CHAN_DISABLED))
+					break;
+			/* if none found then use the first anyway */
+			if (i == sband->n_channels)
+				i = 0;
 			cfg80211_chandef_create(&dflt_chandef,
-						&sband->channels[0],
+						&sband->channels[i],
 						NL80211_CHAN_NO_HT);
 			/* init channel we're on */
 			if (!local->use_chanctx && !local->_oper_chandef.chan) {
-- 
2.30.1