linux-kernel - [PATCH 5.14 373/849] ath10k: sdio: Add missing BH locking around napi

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Date:   Mon, 15 Nov 2021 17:57:36 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Fabio Estevam <festevam@...x.de>,
        Kalle Valo <kvalo@...eaurora.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 373/849] ath10k: sdio: Add missing BH locking around napi_schdule()

From: Fabio Estevam <festevam@...x.de>

[ Upstream commit 019edd01d174ce4bb2e517dd332922514d176601 ]

On a i.MX-based board with a QCA9377 Wifi chip, the following errors
are seen after launching the 'hostapd' application:

hostapd /etc/wifi.conf
Configuration file: /etc/wifi.conf
wlan0: interface state UNINITIALIZED->COUNTRY_UPDATE
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
Using interface wlan0 with hwaddr 00:1f:7b:31:04:a0 and ssid "thessid"
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
wlan0: interface state COUNTRY_UPDATE->ENABLED
wlan0: AP-ENABLED
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
...

Fix this problem by adding the BH locking around napi-schedule(),
in the same way it was done in commit e63052a5dd3c ("mlx5e: add
add missing BH locking around napi_schdule()").

Its commit log provides the following explanation:

"It's not correct to call napi_schedule() in pure process
context. Because we use __raise_softirq_irqoff() we require
callers to be in a context which will eventually lead to
softirq handling (hardirq, bh disabled, etc.).

With code as is users will see:

NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!
"

Fixes: cfee8793a74d ("ath10k: enable napi on RX path for sdio")
Signed-off-by: Fabio Estevam <festevam@...x.de>
Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
Link: https://lore.kernel.org/r/20210824144339.2796122-1-festevam@denx.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/ath/ath10k/sdio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/sdio.c b/drivers/net/wireless/ath/ath10k/sdio.c
index b746052737e0b..eb705214f3f0a 100644
--- a/drivers/net/wireless/ath/ath10k/sdio.c
+++ b/drivers/net/wireless/ath/ath10k/sdio.c
@@ -1363,8 +1363,11 @@ static void ath10k_rx_indication_async_work(struct work_struct *work)
 		ep->ep_ops.ep_rx_complete(ar, skb);
 	}

-	if (test_bit(ATH10K_FLAG_CORE_REGISTERED, &ar->dev_flags))
+	if (test_bit(ATH10K_FLAG_CORE_REGISTERED, &ar->dev_flags)) {
+		local_bh_disable();
 		napi_schedule(&ar->napi);
+		local_bh_enable();
+	}
 }

 static int ath10k_sdio_read_rtc_state(struct ath10k_sdio *ar_sdio, unsigned char *state)
-- 
2.33.0