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[SCSI] zfcp: Recover from stalled outbound queue

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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@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This commit is contained in:
Christof Schmitt 2009-07-13 15:06:10 +02:00 committed by James Bottomley
parent 85600f7f83
commit cbf1ed0264
1 changed files with 4 additions and 1 deletions
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5
drivers/s390/scsi/zfcp_fsf.c
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@ -670,8 +670,11 @@ static int zfcp_fsf_req_sbal_get(struct zfcp_adapter *adapter)
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;