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[02/42] scsi_ioctl: return error code when blk_rq_map_kern() fails

Message ID 20210421174749.11221-3-hare@suse.de
State Superseded
Headers show
Series SCSI result cleanup, part 2 | expand

Commit Message

Hannes Reinecke April 21, 2021, 5:47 p.m. UTC
The callers of sg_scsi_ioctl() already check for negative
return values, so we can drop the usage of DRIVER_ERROR
and return the error from blk_rq_map_kern() instead.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/scsi_ioctl.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Hannes Reinecke April 22, 2021, 6:29 a.m. UTC | #1
On 4/21/21 11:01 PM, Bart Van Assche wrote:
> On 4/21/21 10:47 AM, Hannes Reinecke wrote:

>> The callers of sg_scsi_ioctl() already check for negative

>> return values, so we can drop the usage of DRIVER_ERROR

>> and return the error from blk_rq_map_kern() instead.

>>

>> Signed-off-by: Hannes Reinecke <hare@suse.de>

>> ---

>>   block/scsi_ioctl.c | 7 ++++---

>>   1 file changed, 4 insertions(+), 3 deletions(-)

>>

>> diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c

>> index 6599bac0a78c..99d58786e0d5 100644

>> --- a/block/scsi_ioctl.c

>> +++ b/block/scsi_ioctl.c

>> @@ -488,9 +488,10 @@ int sg_scsi_ioctl(struct request_queue *q, struct 

>> gendisk *disk, fmode_t mode,

>>           break;

>>       }

>> -    if (bytes && blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO)) {

>> -        err = DRIVER_ERROR << 24;

>> -        goto error;

>> +    if (bytes) {

>> +        err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO);

>> +        if (err)

>> +            goto error;

>>       }

>>       blk_execute_rq(disk, rq, 0);

> 

> Is this perhaps a backwards-incompatible user space ABI change since the 

> sg_scsi_ioctl() return value is reported to user space?

> 

Possibly; but we're dealing with semantics here.
All callers to sg_scsi_ioctl() _must_ be prepared to handle negative
values already, so userspace should not break.
We arguably _do_ return a different error here, but experience showed 
that basically no-one checks for driver byte values (except for 
DRIVER_SENSE, that is).
So I don't think it really matters; we do return an error, and for 
userspace it doesn't matter as this command cannot be retried either way.

So while this arguably is a change visible to userspace, I doubt it 
matters in the end.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
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Patch

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 6599bac0a78c..99d58786e0d5 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -488,9 +488,10 @@  int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
 		break;
 	}
 
-	if (bytes && blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO)) {
-		err = DRIVER_ERROR << 24;
-		goto error;
+	if (bytes) {
+		err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO);
+		if (err)
+			goto error;
 	}
 
 	blk_execute_rq(disk, rq, 0);