Re: [PATCH] mmc: dw_mmc: Only inject fault before done/error

[Jaehoon Chung]

On 8/25/21 8:42 PM, Vincent Whitchurch wrote:
> The fault injection function can set EVENT_DATA_ERROR but skip the
> setting of ->data_status to an error status if it hits just after a data
> over interrupt.  This confuses the tasklet which can later end up
> triggering the WARN_ON(host->cmd || ..) in dw_mci_request_end() since
> dw_mci_data_complete() would return success.
> 
> Prevent the fault injection function from doing this since this is not a
> real case, and ensure that the fault injection doesn't race with a real
> error either.
> 
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>

Reviewed-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>

Best Regards,
Jaehoon Chung

> ---
>  drivers/mmc/host/dw_mmc.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 6578cc64ae9e..380f9aa56eb2 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1802,10 +1802,15 @@ static enum hrtimer_restart dw_mci_fault_timer(struct hrtimer *t)
>  
>  	spin_lock_irqsave(&host->irq_lock, flags);
>  
> -	if (!host->data_status)
> +	/*
> +	 * Only inject an error if we haven't already got an error or data over
> +	 * interrupt.
> +	 */
> +	if (!host->data_status) {
>  		host->data_status = SDMMC_INT_DCRC;
> -	set_bit(EVENT_DATA_ERROR, &host->pending_events);
> -	tasklet_schedule(&host->tasklet);
> +		set_bit(EVENT_DATA_ERROR, &host->pending_events);
> +		tasklet_schedule(&host->tasklet);
> +	}
>  
>  	spin_unlock_irqrestore(&host->irq_lock, flags);
>  
> @@ -2721,12 +2726,16 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
>  		}
>  
>  		if (pending & DW_MCI_DATA_ERROR_FLAGS) {
> +			spin_lock(&host->irq_lock);
> +
>  			/* if there is an error report DATA_ERROR */
>  			mci_writel(host, RINTSTS, DW_MCI_DATA_ERROR_FLAGS);
>  			host->data_status = pending;
>  			smp_wmb(); /* drain writebuffer */
>  			set_bit(EVENT_DATA_ERROR, &host->pending_events);
>  			tasklet_schedule(&host->tasklet);
> +
> +			spin_unlock(&host->irq_lock);
>  		}
>  
>  		if (pending & SDMMC_INT_DATA_OVER) {
>