[RFC PATCH] ata: pata_macio: Use WARN instead of BUG

[RFC PATCH] ata: pata_macio: Use WARN instead of BUG

[Michael Ellerman]

The overflow/underflow conditions in pata_macio_qc_prep() should never
happen. But if they do there's no need to kill the system entirely, a
WARN and failing the IO request should be sufficient and might allow the
system to keep running.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 drivers/ata/pata_macio.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Not sure if AC_ERR_OTHER is the right error code to use?

diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c
index eaffa510de49..552e3ac0d391 100644
--- a/drivers/ata/pata_macio.c
+++ b/drivers/ata/pata_macio.c
@@ -554,7 +554,8 @@ static enum ata_completion_errors pata_macio_qc_prep(struct ata_queued_cmd *qc)
 
 		while (sg_len) {
 			/* table overflow should never happen */
-			BUG_ON (pi++ >= MAX_DCMDS);
+			if (WARN_ON_ONCE(pi >= MAX_DCMDS))
+				return AC_ERR_OTHER;
 
 			len = (sg_len < MAX_DBDMA_SEG) ? sg_len : MAX_DBDMA_SEG;
 			table->command = cpu_to_le16(write ? OUTPUT_MORE: INPUT_MORE);
@@ -566,11 +567,13 @@ static enum ata_completion_errors pata_macio_qc_prep(struct ata_queued_cmd *qc)
 			addr += len;
 			sg_len -= len;
 			++table;
+			++pi;
 		}
 	}
 
 	/* Should never happen according to Tejun */
-	BUG_ON(!pi);
+	if (WARN_ON_ONCE(!pi))
+		return AC_ERR_OTHER;
 
 	/* Convert the last command to an input/output */
 	table--;
-- 
2.46.0

Re: [RFC PATCH] ata: pata_macio: Use WARN instead of BUG

[Damien Le Moal]

On 8/19/24 19:19, Michael Ellerman wrote:
> The overflow/underflow conditions in pata_macio_qc_prep() should never
> happen. But if they do there's no need to kill the system entirely, a
> WARN and failing the IO request should be sufficient and might allow the
> system to keep running.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
>  drivers/ata/pata_macio.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Not sure if AC_ERR_OTHER is the right error code to use?

Given that this would trigger if the command split has is buggy, I think that
AC_ERR_SYSTEM would be better. Can you resend with the change and no "RFC" ?

> 
> diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c
> index eaffa510de49..552e3ac0d391 100644
> --- a/drivers/ata/pata_macio.c
> +++ b/drivers/ata/pata_macio.c
> @@ -554,7 +554,8 @@ static enum ata_completion_errors pata_macio_qc_prep(struct ata_queued_cmd *qc)
>  
>  		while (sg_len) {
>  			/* table overflow should never happen */
> -			BUG_ON (pi++ >= MAX_DCMDS);
> +			if (WARN_ON_ONCE(pi >= MAX_DCMDS))
> +				return AC_ERR_OTHER;
>  
>  			len = (sg_len < MAX_DBDMA_SEG) ? sg_len : MAX_DBDMA_SEG;
>  			table->command = cpu_to_le16(write ? OUTPUT_MORE: INPUT_MORE);
> @@ -566,11 +567,13 @@ static enum ata_completion_errors pata_macio_qc_prep(struct ata_queued_cmd *qc)
>  			addr += len;
>  			sg_len -= len;
>  			++table;
> +			++pi;
>  		}
>  	}
>  
>  	/* Should never happen according to Tejun */
> -	BUG_ON(!pi);
> +	if (WARN_ON_ONCE(!pi))
> +		return AC_ERR_OTHER;
>  
>  	/* Convert the last command to an input/output */
>  	table--;

-- 
Damien Le Moal
Western Digital Research

Re: [RFC PATCH] ata: pata_macio: Use WARN instead of BUG

[Michael Ellerman]

Damien Le Moal <dlemoal@kernel.org> writes:
> On 8/19/24 19:19, Michael Ellerman wrote:
>> The overflow/underflow conditions in pata_macio_qc_prep() should never
>> happen. But if they do there's no need to kill the system entirely, a
>> WARN and failing the IO request should be sufficient and might allow the
>> system to keep running.
>> 
>> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
>> ---
>>  drivers/ata/pata_macio.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> 
>> Not sure if AC_ERR_OTHER is the right error code to use?
>
> Given that this would trigger if the command split has is buggy, I think that
> AC_ERR_SYSTEM would be better. Can you resend with the change and no "RFC" ?

Will do.

cheers