On Mon, 2016-06-13 at 22:00 -0700, James Bottomley wrote:
> The untagged command case in the 53c700 driver has been broken since
> host wide tags were enabled because the replaced scsi_find_tag()
> function had a special case for the tag value SCSI_NO_TAG to retrieve
> sdev->current_cmnd. The replacement function scsi_host_find_tag() has
> no such special case and returns NULL causing untagged commands to
> trigger a BUG() in the driver. Inspection shows that the 53c700 is the
> only driver using this SCSI_NO_TAG case, so a local fix in the driver
> suffices to fix this problem globally.
>
> Fixes: 64d513ac31b - "scsi: use host wide tags by default"
> Cc: stable@xxxxxxxxxxxxxxx # 4.4+
> Reported-by: Helge Deller <deller@xxxxxx>
> Tested-by: Helge Deller <deller@xxxxxx>
> Signed-off-by: James Bottomley <jejb@xxxxxxxxxxxxxxxxxx>
>
> ---
>
> diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
> index d4c2856..3ddc85e 100644
> --- a/drivers/scsi/53c700.c
> +++ b/drivers/scsi/53c700.c
> @@ -1122,7 +1122,7 @@ process_script_interrupt(__u32 dsps, __u32 dsp, struct scsi_cmnd *SCp,
> } else {
> struct scsi_cmnd *SCp;
>
> - SCp = scsi_host_find_tag(SDp->host, SCSI_NO_TAG);
> + SCp = SDp->current_cmnd;
> if(unlikely(SCp == NULL)) {
> sdev_printk(KERN_ERR, SDp,
> "no saved request for untagged cmd\n");
> @@ -1826,7 +1826,7 @@ NCR_700_queuecommand_lck(struct scsi_cmnd *SCp, void (*done)(struct scsi_cmnd *)
> slot->tag, slot);
> } else {
> slot->tag = SCSI_NO_TAG;
> - /* must populate current_cmnd for scsi_host_find_tag to work */
> + /* save current command for reselection */
> SCp->device->current_cmnd = SCp;
> }
> /* sanity check: some of the commands generated by the mid-layer
>
>
> --
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Reviewed-by: Ewan D. Milne <emilne@xxxxxxxxxx>
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