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    Subject[PATCH 5.14 373/849] ath10k: sdio: Add missing BH locking around napi_schdule()
    Date
    From: Fabio Estevam <festevam@denx.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@denx.de>
    Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
    Link: https://lore.kernel.org/r/20210824144339.2796122-1-festevam@denx.de
    Signed-off-by: Sasha Levin <sashal@kernel.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


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