Mike Christie wrote:
Hannes Reinecke wrote:
Hi all,
currently the initialisation of scmd->tag seems to be wrong.
We have this lines from scsi_lib.c:scsi_get_cmd_from_req():
/* pull a tag out of the request if we have one */
cmd->tag = req->tag;
which are supposed to fill the tag value for a given command.
However, the function is called from the ->prep_fn callback,
invoked from elv_next_request() in scsi_request_fn().
In scsi_request_fn() we have:
req = elv_next_request(q);
if (!req || !scsi_dev_queue_ready(q, sdev))
break;
if (unlikely(!scsi_device_online(sdev))) {
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
scsi_kill_request(req, q);
continue;
}
/*
* Remove the request from the request list.
*/
if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
blkdev_dequeue_request(req);
ie the value of rq->tag is filled _after it has been copied
to scmd->tag.
A proposed patch would be:
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1055,8 +1055,6 @@ static struct scsi_cmnd
*scsi_get_cmd_from_req(struct scsi_device *sdev,
cmd = req->special;
}
- /* pull a tag out of the request if we have one */
- cmd->tag = req->tag;
cmd->request = req;
return cmd;
@@ -1445,6 +1443,9 @@ static void scsi_request_fn(struct request_queue
*q)
blk_dump_rq_flags(req, "foo");
BUG();
}
+ /* pull a tag out of the request if we have one */
+ cmd->tag = req->tag;
+
spin_lock(shost->host_lock);
if (!scsi_host_queue_ready(q, shost, sdev))
Comments?
I saw that while working on qla4xxx. I think the reason no one ever
complained before is because of how most drivers use the tags. Was there
some driver accesing the scsi cmd tag value?
Ignore that question. I forgot about your other patch.
-
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