[PATCH] wifi: mt76: mt7921s: fix potential hung tasks during chip recovery

[Ben Greear]

On 3/7/24 01:46, Mingyen Hsieh wrote:
> From: Leon Yen <leon.yen at mediatek.com>
> 
> During chip recovery (e.g. chip reset), there is a possible situation that
> kernel worker reset_work is holding the lock and waiting for kernel thread
> stat_worker to be parked, while stat_worker is waiting for the release of
> the same lock.
> It causes a deadlock resulting in the dumping of hung tasks messages and
> possible rebooting of the device.
> 
> This patch prevents the execution of stat_worker during the chip recovery.

Hello,

I was able to hang my 7996 system doing a radio reset yesterday.  Is this same
or similar fix needed for 7996?

Thanks
Ben

> 
> Signed-off-by: Leon Yen <leon.yen at mediatek.com>
> Signed-off-by: Ming Yen Hsieh <MingYen.Hsieh at mediatek.com>
> ---
>   drivers/net/wireless/mediatek/mt76/mt7921/mac.c      | 2 ++
>   drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c  | 2 --
>   drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c | 2 --
>   drivers/net/wireless/mediatek/mt76/sdio.c            | 3 ++-
>   4 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> index 867e14f6b93a..73e42ef42983 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> @@ -663,6 +663,7 @@ void mt7921_mac_reset_work(struct work_struct *work)
>   	int i, ret;
>   
>   	dev_dbg(dev->mt76.dev, "chip reset\n");
> +	set_bit(MT76_RESET, &dev->mphy.state);
>   	dev->hw_full_reset = true;
>   	ieee80211_stop_queues(hw);
>   
> @@ -691,6 +692,7 @@ void mt7921_mac_reset_work(struct work_struct *work)
>   	}
>   
>   	dev->hw_full_reset = false;
> +	clear_bit(MT76_RESET, &dev->mphy.state);
>   	pm->suspended = false;
>   	ieee80211_wake_queues(hw);
>   	ieee80211_iterate_active_interfaces(hw,
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
> index c866144ff061..031ba9aaa4e2 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
> @@ -64,7 +64,6 @@ int mt7921e_mac_reset(struct mt792x_dev *dev)
>   	mt76_wr(dev, dev->irq_map->host_irq_enable, 0);
>   	mt76_wr(dev, MT_PCIE_MAC_INT_ENABLE, 0x0);
>   
> -	set_bit(MT76_RESET, &dev->mphy.state);
>   	set_bit(MT76_MCU_RESET, &dev->mphy.state);
>   	wake_up(&dev->mt76.mcu.wait);
>   	skb_queue_purge(&dev->mt76.mcu.res_q);
> @@ -115,7 +114,6 @@ int mt7921e_mac_reset(struct mt792x_dev *dev)
>   
>   	err = __mt7921_start(&dev->phy);
>   out:
> -	clear_bit(MT76_RESET, &dev->mphy.state);
>   
>   	local_bh_disable();
>   	napi_enable(&dev->mt76.tx_napi);
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c
> index 389eb0903807..1f77cf71ca70 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c
> @@ -98,7 +98,6 @@ int mt7921s_mac_reset(struct mt792x_dev *dev)
>   	mt76_connac_free_pending_tx_skbs(&dev->pm, NULL);
>   	mt76_txq_schedule_all(&dev->mphy);
>   	mt76_worker_disable(&dev->mt76.tx_worker);
> -	set_bit(MT76_RESET, &dev->mphy.state);
>   	set_bit(MT76_MCU_RESET, &dev->mphy.state);
>   	wake_up(&dev->mt76.mcu.wait);
>   	skb_queue_purge(&dev->mt76.mcu.res_q);
> @@ -135,7 +134,6 @@ int mt7921s_mac_reset(struct mt792x_dev *dev)
>   
>   	err = __mt7921_start(&dev->phy);
>   out:
> -	clear_bit(MT76_RESET, &dev->mphy.state);
>   
>   	mt76_worker_enable(&dev->mt76.tx_worker);
>   
> diff --git a/drivers/net/wireless/mediatek/mt76/sdio.c b/drivers/net/wireless/mediatek/mt76/sdio.c
> index 3e88798df017..a4ed00eebc48 100644
> --- a/drivers/net/wireless/mediatek/mt76/sdio.c
> +++ b/drivers/net/wireless/mediatek/mt76/sdio.c
> @@ -499,7 +499,8 @@ static void mt76s_tx_status_data(struct mt76_worker *worker)
>   	dev = container_of(sdio, struct mt76_dev, sdio);
>   
>   	while (true) {
> -		if (test_bit(MT76_REMOVED, &dev->phy.state))
> +		if (test_bit(MT76_RESET, &dev->phy.state) ||
> +		    test_bit(MT76_REMOVED, &dev->phy.state))
>   			break;
>   
>   		if (!dev->drv->tx_status_data(dev, &update))

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com