[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, 2 insertions, 2 deletions

diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index 306fcd0cae31..adfbbb07448a 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -136,7 +136,6 @@ zfcp_address_to_sg(void *address, struct scatterlist *list, unsigned int size)
 #define ZFCP_QTCB_VERSION       FSF_QTCB_CURRENT_VERSION
 /* ATTENTION: value must not be used by hardware */
 #define FSF_QTCB_UNSOLICITED_STATUS             0x6305
-#define ZFCP_STATUS_READ_FAILED_THRESHOLD       3
 #define ZFCP_STATUS_READS_RECOM                 FSF_STATUS_READS_RECOM
 
 /* Do 1st retry in 1 second, then double the timeout for each following retry */
@@ -759,7 +758,8 @@ struct zfcp_adapter {
         rwlock_t                abort_lock;        /* Protects against SCSI
                                                       stack abort/command
                                                       completion races */
-        u16                     status_read_failed; /* # failed status reads */
+        atomic_t                stat_miss;         /* # missing status reads*/
+        struct work_struct      stat_work;
         atomic_t                status;            /* status of this adapter */
         struct list_head        erp_ready_head;    /* error recovery for this
                                                       adapter/devices */