Re: [PATCH 1/4] mt76: mt7921e: fix race issue between reset and suspend/resume

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> From: Sean Wang <sean.wang@mediatek.com>
> 
> It is unexpected that the reset work is running simultaneously with
> the suspend or resume context and it is possible that reset work is still
> running even after mt7921 is suspended if we don't fix the race issue.
> 
> Thus, the suspend procedure should be waiting until the reset is completed
> at the beginning and ignore the subsequent the reset requests.
> 
> In case there is an error that happens during either suspend or resume
> handler, we will schedule a reset task to recover the error before
> returning the error code to ensure we can immediately fix the error there.
> 
> Fixes: 0c1ce9884607 ("mt76: mt7921: add wifi reset support")
> Co-developed-by: YN Chen <YN.Chen@mediatek.com>
> Signed-off-by: YN Chen <YN.Chen@mediatek.com>
> Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7921/mac.c |  5 +++++
>  drivers/net/wireless/mediatek/mt76/mt7921/pci.c | 13 +++++++++----
>  2 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> index 47f0aa81ab02..6bd9fc9228a2 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
> @@ -780,6 +780,7 @@ void mt7921_mac_reset_work(struct work_struct *work)
>  void mt7921_reset(struct mt76_dev *mdev)
>  {
>  	struct mt7921_dev *dev = container_of(mdev, struct mt7921_dev, mt76);
> +	struct mt76_connac_pm *pm = &dev->pm;
>  
>  	if (!dev->hw_init_done)
>  		return;
> @@ -787,8 +788,12 @@ void mt7921_reset(struct mt76_dev *mdev)
>  	if (dev->hw_full_reset)
>  		return;
>  
> +	if (pm->suspended)
> +		return;
> +
>  	queue_work(dev->mt76.wq, &dev->reset_work);
>  }
> +EXPORT_SYMBOL_GPL(mt7921_reset);
>  
>  void mt7921_mac_update_mib_stats(struct mt7921_phy *phy)
>  {
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> index 9d1ba838e54f..07573ea55389 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> @@ -363,6 +363,7 @@ static int mt7921_pci_suspend(struct device *device)
>  	int i, err;
>  
>  	pm->suspended = true;
> +	cancel_work_sync(&dev->reset_work);

should we just wait for the reset to complete here instead of cancelling? (e.g. flush_work)

Regards,
Lorenzo

>  	cancel_delayed_work_sync(&pm->ps_work);
>  	cancel_work_sync(&pm->wake_work);
>  
> @@ -424,6 +425,9 @@ static int mt7921_pci_suspend(struct device *device)
>  restore_suspend:
>  	pm->suspended = false;
>  
> +	if (err < 0)
> +		mt7921_reset(&dev->mt76);
> +
>  	return err;
>  }
>  
> @@ -437,7 +441,7 @@ static int mt7921_pci_resume(struct device *device)
>  
>  	err = mt7921_mcu_drv_pmctrl(dev);
>  	if (err < 0)
> -		return err;
> +		goto failed;
>  
>  	mt7921_wpdma_reinit_cond(dev);
>  
> @@ -467,11 +471,12 @@ static int mt7921_pci_resume(struct device *device)
>  		mt76_connac_mcu_set_deep_sleep(&dev->mt76, false);
>  
>  	err = mt76_connac_mcu_set_hif_suspend(mdev, false);
> -	if (err)
> -		return err;
> -
> +failed:
>  	pm->suspended = false;
>  
> +	if (err < 0)
> +		mt7921_reset(&dev->mt76);
> +
>  	return err;
>  }
>  
> -- 
> 2.25.1
> 

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