Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control

Johannes Thumshirn
2017-07-19T07:03:35Z

On Tue, Jul 18, 2017 at 12:33:59PM -0500, Jason L Tibbitts III wrote:
> I have verified that building a clean v4.12 with
> 68c59fcea1f2c6a54c62aa896cc623c1b5bc9b47 cherry picked on top still
> shows the problem:
>
> [root@backup2 ~]# mtx -f /dev/sg7 next 0
> Unloading drive 0 into Storage Element 45...mtx: Request Sense: Long
> Report=yes
> mtx: Request Sense: Valid Residual=no
> mtx: Request Sense: Error Code=0 (Unknown?!)
> mtx: Request Sense: Sense Key=No Sense
> mtx: Request Sense: FileMark=no
> mtx: Request Sense: EOM=no
> mtx: Request Sense: ILI=no
> mtx: Request Sense: Additional Sense Code = 00
> mtx: Request Sense: Additional Sense Qualifier = 00
> mtx: Request Sense: BPV=no
> mtx: Request Sense: Error in CDB=no
> mtx: Request Sense: SKSV=no
> MOVE MEDIUM from Element Address 1 to 1045 Failed
>
> Nothing appears to be logged; is there any kind of debugging information
> I can collect which might help to track this down? I'm not particularly
> good at this but I am pretty sure that I'm building everything properly
> and am actually booting the patched kernel.

Can you please apply this debugging patch, so I can see what's going on.

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 1e82d4128a84..2505fa0b2062 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -753,6 +753,10 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,

static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
{
+
+ pr_info("%s: dxfer_direction: %d, dxfer_len: %d\n",
+ __func__, hp->dxfer_direction, hp->dxfer_len);
+
switch (hp->dxfer_direction) {
case SG_DXFER_NONE:
if (hp->dxferp || hp->dxfer_len > 0)

Thanks,
Johannes
--
Johannes Thumshirn Storage
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