[SCSI] zfcp: receiving an unsolicted status can lead to I/O stall

Processing of an unsolicted status request can lead to a locking race
of the request_queue's queue_lock during the recreation of the
used up status read request while still in interrupt context
of the response handler.

Detaching the 'refill' of the long running status read requests from
the handler to a scheduled work is solving this issue.

In addition, each refill-run is trying to re-establish the full amount
of status read requests, which might have failed in earlier runs.

Signed-off-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>

1 files changed, 3 insertions, 15 deletions

diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 1e7136483c1..b344e8a72f1 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -1029,21 +1029,9 @@ zfcp_fsf_status_read_handler(struct zfcp_fsf_req *fsf_req)
          * FIXME:
          * allocation failure possible? (Is this code needed?)
          */
-        retval = zfcp_fsf_status_read(adapter, 0);
-        if (retval < 0) {
-                ZFCP_LOG_INFO("Failed to create unsolicited status read "
-                              "request for the adapter %s.\n",
-                              zfcp_get_busid_by_adapter(adapter));
-                /* temporary fix to avoid status read buffer shortage */
-                adapter->status_read_failed++;
-                if ((ZFCP_STATUS_READS_RECOM - adapter->status_read_failed)
-                    < ZFCP_STATUS_READ_FAILED_THRESHOLD) {
-                        ZFCP_LOG_INFO("restart adapter %s due to status read "
-                                      "buffer shortage\n",
-                                      zfcp_get_busid_by_adapter(adapter));
-                        zfcp_erp_adapter_reopen(adapter, 0, 103, fsf_req);
-                }
-        }
+
+        atomic_inc(&adapter->stat_miss);
+        schedule_work(&adapter->stat_work);
  out:
         return retval;
 }