From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Sat, 13 Nov 2021 17:24:52 +0000 (+0100)
Subject: mac80211: Fix deadlock when configuring wifi
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c90e10b62eaccb71d289c3f7a7c67dcbae0b74f8;p=openwrt%2Fstaging%2Fxback.git

mac80211: Fix deadlock when configuring wifi

The nl80211_set_wiphy() function was changed between kernel 5.11 and
5.12 to take the rdev->wiphy lock which should be freed at the end
again. The 500-mac80211_configure_antenna_gain.patch added some code
which just returned in some cases without unlocking. This resulted in a
deadlock with brcmfmac.
This patch fixes this by also jumping to the out label in case we want
to leave the function.
This fixes a hanging system when brcmfmac is in use. I do not know why
we do not see this with other driver.

The kernel returns very useful debug details when setting these OpenWrt
configuration options:
CONFIG_KERNEL_DETECT_HUNG_TASK=y
CONFIG_KERNEL_PROVE_LOCKING=y

Fixes: FS#4122
Fixes: b96c2569ac76 ("mac80211: Update to version 5.12.19-1")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
---

diff --git a/package/kernel/mac80211/patches/subsys/500-mac80211_configure_antenna_gain.patch b/package/kernel/mac80211/patches/subsys/500-mac80211_configure_antenna_gain.patch
index 3f2cc18253..821032fa89 100644
--- a/package/kernel/mac80211/patches/subsys/500-mac80211_configure_antenna_gain.patch
+++ b/package/kernel/mac80211/patches/subsys/500-mac80211_configure_antenna_gain.patch
@@ -137,24 +137,26 @@
  };
  
  /* policy for the key attributes */
-@@ -3325,6 +3326,20 @@ static int nl80211_set_wiphy(struct sk_b
+@@ -3324,6 +3325,22 @@ static int nl80211_set_wiphy(struct sk_b
+ 		if (result)
  			goto out;
  	}
- 
++
 +	if (info->attrs[NL80211_ATTR_WIPHY_ANTENNA_GAIN]) {
 +		int idx, dbi = 0;
 +
-+		if (!rdev->ops->set_antenna_gain)
-+			return -EOPNOTSUPP;
++		if (!rdev->ops->set_antenna_gain) {
++			result = -EOPNOTSUPP;
++			goto out;
++		}
 +
 +		idx = NL80211_ATTR_WIPHY_ANTENNA_GAIN;
 +		dbi = nla_get_u32(info->attrs[idx]);
 +
 +		result = rdev->ops->set_antenna_gain(&rdev->wiphy, dbi);
 +		if (result)
-+			return result;
++			goto out;
 +	}
-+
+ 
  	if (info->attrs[NL80211_ATTR_WIPHY_TX_POWER_SETTING]) {
  		struct wireless_dev *txp_wdev = wdev;
- 		enum nl80211_tx_power_setting type;