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

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

[Vincent Whitchurch]

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@axis.com>
---
 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) {
-- 
2.28.0

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@axis.com>

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

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) {
> 

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

[Ulf Hansson]

On Wed, 25 Aug 2021 at 13:42, Vincent Whitchurch
<vincent.whitchurch@axis.com> 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@axis.com>

Applied for fixes and by adding a fixes tag, thanks!

Kind regards
Uffe


> ---
>  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) {
> --
> 2.28.0
>