Messages in this thread | | | Subject | Re: [PATCH] scsi: sg: fix SG_DXFER_FROM_DEV transfers | From | Douglas Gilbert <> | Date | Thu, 6 Jul 2017 14:47:22 -0400 |
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On 2017-07-05 09:49 AM, Johannes Thumshirn wrote: > SG_DXFER_FROM_DEV transfers do not have a dxferp as we set it to NULL, > but must have a length bigger than 0. This fixes a regression introduced > by commit 28676d869bbb ("scsi: sg: check for valid direction before > starting the request")
It is not clear to me that dxferp is set to NULL for the newer sg_v3 interface. In the sg.c source of lk 4.12.0 around line 654 (in the sg_write(...) function) only the older interface passes through; the newer interface bypasses that section with a 'return sg_new_write(...)' on line 606.
Can you check your patch with one of the utilities from sg3_utils such as sg_inq which will use SG_DXFER_FROM_DEV with the newer interface?
BTW I'm not sure why dxferp is set to NULL for SG_DXFER_FROM_DEV transfers; perhaps some magic done by the block layer. Maybe a comment in the code (e.g. on line 654) would help.
Also sg_is_valid_dxfer() is only called once and is more complex than it looks; so perhaps it could be inlined back in sg_common_write().
Doug Gilbert
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de> > Fixes: 28676d869bbb ("scsi: sg: check for valid direction before starting the request") > Reported-by: Chris Clayton <chris2553@googlemail.com> > Tested-by: Chris Clayton <chris2553@googlemail.com> > Cc: Doug Gilbert <dgilbert@interlog.com> > --- > drivers/scsi/sg.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c > index 21225d62b0c1..3c91593260aa 100644 > --- a/drivers/scsi/sg.c > +++ b/drivers/scsi/sg.c > @@ -758,8 +758,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_t *hp) > if (hp->dxferp || hp->dxfer_len > 0) > return false; > return true; > - case SG_DXFER_TO_DEV: > case SG_DXFER_FROM_DEV: > + if (hp->dxferp || hp->dxfer_len < 0) > + return false; > + return true; > + case SG_DXFER_TO_DEV: > case SG_DXFER_TO_FROM_DEV: > if (!hp->dxferp || hp->dxfer_len == 0) > return false; >
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