From: Christof Schmitt <christof.schmitt@xxxxxxxxxx>
Depending on interruptions on some storage systems, the complete
channel can stall which looks like an outbound queue stall to Linux.
When trying to acquire a free SBAL for a non-SCSI command, zfcp waits
for 5 seconds for a free slot to appear. This is the right place to
detect a queue stall: If the wait times out, we assume a stalled queue
and try to recover this.
The overall strategy should be to trigger the erp from specific
events, and not try an overall escalation from one failed port to a
full-blown queue recovery. If we manage to send a command, the status
codes for this command or a timeout will trigger the right follow-on
actions.
Reviewed-by: Swen Schillig <swen@xxxxxxxxxxxx>
Signed-off-by: Christof Schmitt <christof.schmitt@xxxxxxxxxx>
---
drivers/s390/scsi/zfcp_fsf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/s390/scsi/zfcp_fsf.c 2009-07-13 13:18:08.000000000 +0200
+++ b/drivers/s390/scsi/zfcp_fsf.c 2009-07-13 13:18:10.000000000 +0200
@@ -670,8 +670,11 @@ static int zfcp_fsf_req_sbal_get(struct
zfcp_fsf_sbal_check(adapter), 5 * HZ);
if (ret > 0)
return 0;
- if (!ret)
+ if (!ret) {
atomic_inc(&adapter->qdio_outb_full);
+ /* assume hanging outbound queue, try queue recovery */
+ zfcp_erp_adapter_reopen(adapter, 0, "fsrsg_1", NULL);
+ }
spin_lock_bh(&adapter->req_q_lock);
return -EIO;
--
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