linux-kernel - [PATCH v3 2/3] wifi: rtw88: Use rtw_iterate_vifs() for rtw_vif_watch_dog

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Message-Id: <20230108211324.442823-3-martin.blumenstingl@googlemail.com>
Date:   Sun,  8 Jan 2023 22:13:23 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     linux-wireless@...r.kernel.org
Cc:     tony0620emma@...il.com, kvalo@...nel.org, pkshih@...ltek.com,
        s.hauer@...gutronix.de, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [PATCH v3 2/3] wifi: rtw88: Use rtw_iterate_vifs() for rtw_vif_watch_dog_iter()

USB and (upcoming) SDIO support may sleep in the read/write handlers.
Make rtw_watch_dog_work() use rtw_iterate_vifs() to prevent "scheduling
while atomic" or "Voluntary context switch within RCU read-side
critical section!" warnings when accessing the registers using an SDIO
card (which is where this issue has been spotted in the real world 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>
Reviewed-by: Ping-Ke Shih <pkshih@...ltek.com>
Tested-by: Sascha Hauer <s.hauer@...gutronix.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
v1 -> v2:
- no change

v2 -> v3:
- Added Ping-Ke's Reviewed-by (thank you!)
- Added Sascha's Tested-by (thank you!)
- added "wifi" prefix to the subject and reworded the title accordingly


 drivers/net/wireless/realtek/rtw88/main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index 888427cf3bdf..b2e78737bd5d 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -241,8 +241,10 @@ static void rtw_watch_dog_work(struct work_struct *work)
 	rtw_phy_dynamic_mechanism(rtwdev);
 
 	data.rtwdev = rtwdev;
-	/* use atomic version to avoid taking local->iflist_mtx mutex */
-	rtw_iterate_vifs_atomic(rtwdev, rtw_vif_watch_dog_iter, &data);
+	/* rtw_iterate_vifs internally uses an atomic iterator which is needed
+	 * to avoid taking local->iflist_mtx mutex
+	 */
+	rtw_iterate_vifs(rtwdev, rtw_vif_watch_dog_iter, &data);
 
 	/* fw supports only one station associated to enter lps, if there are
 	 * more than two stations associated to the AP, then we can not enter
-- 
2.39.0