linux-kernel - [PATCH 4/4] rtw88: Use non-atomic rtw_iterate_stas() in rtw_ra_mask_info

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Date:   Wed, 28 Dec 2022 14:35:47 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     linux-wireless@...r.kernel.org
Cc:     tony0620emma@...il.com, kvalo@...nel.org, pkshih@...ltek.com,
        tehuang@...ltek.com, s.hauer@...gutronix.de,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [PATCH 4/4] rtw88: Use non-atomic rtw_iterate_stas() in rtw_ra_mask_info_update()

USB and (upcoming) SDIO support may sleep in the read/write handlers.
Use non-atomic rtw_iterate_stas() in rtw_ra_mask_info_update() because
the iterator function rtw_ra_mask_info_update_iter() needs to read and
write registers from within rtw_update_sta_info(). Using the non-atomic
iterator ensures that we can sleep during USB and SDIO register reads
and writes. This fixes "scheduling while atomic" or "Voluntary context
switch within RCU read-side critical section!" warnings as seen by SDIO
card users (but it also affects USB cards).

Fixes: 78d5bf925f30 ("wifi: rtw88: iterate over vif/sta list non-atomically")
Suggested-by: Ping-Ke Shih <pkshih@...ltek.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
 drivers/net/wireless/realtek/rtw88/mac80211.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtw88/mac80211.c b/drivers/net/wireless/realtek/rtw88/mac80211.c
index 776a9a9884b5..3b92ac611d3f 100644
--- a/drivers/net/wireless/realtek/rtw88/mac80211.c
+++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
@@ -737,7 +737,7 @@ static void rtw_ra_mask_info_update(struct rtw_dev *rtwdev,
 	br_data.rtwdev = rtwdev;
 	br_data.vif = vif;
 	br_data.mask = mask;
-	rtw_iterate_stas_atomic(rtwdev, rtw_ra_mask_info_update_iter, &br_data);
+	rtw_iterate_stas(rtwdev, rtw_ra_mask_info_update_iter, &br_data);
 }
 
 static int rtw_ops_set_bitrate_mask(struct ieee80211_hw *hw,
@@ -746,7 +746,9 @@ static int rtw_ops_set_bitrate_mask(struct ieee80211_hw *hw,
 {
 	struct rtw_dev *rtwdev = hw->priv;
 
+	mutex_lock(&rtwdev->mutex);
 	rtw_ra_mask_info_update(rtwdev, vif, mask);
+	mutex_unlock(&rtwdev->mutex);
 
 	return 0;
 }
-- 
2.39.0