[PATCH 4.6 192/203] 53c700: fix BUG on untagged commands

Greg Kroah-Hartman
2016-07-25T21:42:44Z

From: James Bottomley <jejb@linux.vnet.ibm.com>

commit 8beb330044d0d1878c7b92290e91c0b889e92633 upstream.

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"
Reported-by: Helge Deller <deller@gmx.de>
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/53c700.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -1122,7 +1122,7 @@ process_script_interrupt(__u32 dsps, __u
} 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_cmn
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