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References: <20210824144339.2796122-1-festevam@denx.de>
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From:   Fabio Estevam <festevam@gmail.com>
Date:   Tue, 31 Aug 2021 15:21:44 -0300
Message-ID: <CAOMZO5De71QvbvAsddCzAmGRULTie3hPqBJgo6ytVV6pEkisXw@mail.gmail.com>
Subject: Re: [PATCH] ath10k: sdio: Add missing BH locking around napi_schdule()
To:     Fabio Estevam <festevam@denx.de>, Kalle Valo <kvalo@codeaurora.org>
Cc:     Jakub Kicinski <kuba@kernel.org>, ath10k@lists.infradead.org,
        linux-wireless <linux-wireless@vger.kernel.org>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Marek Vasut <marex@denx.de>, wgong@codeaurora.org,
        alagusankar@silex-india.com, erik.stromdahl@gmail.com
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Precedence: bulk

Hi Kalle,

On Tue, Aug 24, 2021 at 11:46 AM Fabio Estevam <festevam@denx.de> wrote:
>
> 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@denx.de>

Gentle ping on this one.