[SCSI] zfcp: Fix request list handling in error path

Fix the handling of the request list in the error path:
 - Use irqsave for the lock as in the good path.
 - Before removing the request, check if it is still in the list, a
   call to dismiss_all might have changed the list in between.
 - zfcp_qdio_send does not change the queue counters on failure,
   trying revert something is wrong, so remove this.

Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 5e8517fc8b62..d024442ee128 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -770,7 +770,6 @@ static struct zfcp_fsf_req *zfcp_fsf_req_create(struct zfcp_adapter *adapter,
 static int zfcp_fsf_req_send(struct zfcp_fsf_req *req)
 {
         struct zfcp_adapter *adapter = req->adapter;
-        struct zfcp_qdio_queue *req_q = &adapter->req_q;
         unsigned long flags;
         int idx;
 
@@ -780,19 +779,15 @@ static int zfcp_fsf_req_send(struct zfcp_fsf_req *req)
         list_add_tail(&req->list, &adapter->req_list[idx]);
         spin_unlock_irqrestore(&adapter->req_list_lock, flags);
 
-        req->qdio_outb_usage = atomic_read(&req_q->count);
+        req->qdio_outb_usage = atomic_read(&adapter->req_q.count);
         req->issued = get_clock();
         if (zfcp_qdio_send(req)) {
-                /* Queues are down..... */
                 del_timer(&req->timer);
-                spin_lock(&adapter->req_list_lock);
-                zfcp_reqlist_remove(adapter, req);
-                spin_unlock(&adapter->req_list_lock);
-                /* undo changes in request queue made for this request */
-                atomic_add(req->sbal_number, &req_q->count);
-                req_q->first -= req->sbal_number;
-                req_q->first += QDIO_MAX_BUFFERS_PER_Q;
-                req_q->first %= QDIO_MAX_BUFFERS_PER_Q; /* wrap */
+                spin_lock_irqsave(&adapter->req_list_lock, flags);
+                /* lookup request again, list might have changed */
+                if (zfcp_reqlist_find_safe(adapter, req))
+                        zfcp_reqlist_remove(adapter, req);
+                spin_unlock_irqrestore(&adapter->req_list_lock, flags);
                 zfcp_erp_adapter_reopen(adapter, 0, 116, req);
                 return -EIO;
         }