[SCSI] iscsi: fix writepsace race

We can race and misset the suspend bit if iscsi_write_space is
called then iscsi_send returns with a failure indicating
there is no space.

To handle this this patch returns a error upwards allowing xmitworker
to decide if we need to try and transmit again. For the no
write space case xmitworker will not retry, and instead
let iscsi_write_space queue it back up if needed (this relies
on the work queue code to properly requeue us if needed).

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 19 insertions, 12 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 256b87a85978..2673a11a9495 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -513,10 +513,11 @@ EXPORT_SYMBOL_GPL(iscsi_conn_failure);
 static int iscsi_data_xmit(struct iscsi_conn *conn)
 {
         struct iscsi_transport *tt;
+        int rc = 0;
 
         if (unlikely(conn->suspend_tx)) {
                 debug_scsi("conn %d Tx suspended!\n", conn->id);
-                return 0;
+                return -ENODATA;
         }
         tt = conn->session->tt;
 
@@ -536,13 +537,15 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
         BUG_ON(conn->ctask && conn->mtask);
 
         if (conn->ctask) {
-                if (tt->xmit_cmd_task(conn, conn->ctask))
+                rc = tt->xmit_cmd_task(conn, conn->ctask);
+                if (rc)
                         goto again;
                 /* done with this in-progress ctask */
                 conn->ctask = NULL;
         }
         if (conn->mtask) {
-                if (tt->xmit_mgmt_task(conn, conn->mtask))
+                rc = tt->xmit_mgmt_task(conn, conn->mtask);
+                if (rc)
                         goto again;
                 /* done with this in-progress mtask */
                 conn->mtask = NULL;
@@ -556,7 +559,8 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                         list_add_tail(&conn->mtask->running,
                                       &conn->mgmt_run_list);
                         spin_unlock_bh(&conn->session->lock);
-                        if (tt->xmit_mgmt_task(conn, conn->mtask))
+                        rc = tt->xmit_mgmt_task(conn, conn->mtask);
+                        if (rc)
                                 goto again;
                 }
                 /* done with this mtask */
@@ -574,7 +578,8 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                 if (list_empty(&conn->ctask->running))
                         list_add_tail(&conn->ctask->running, &conn->run_list);
                 spin_unlock_bh(&conn->session->lock);
-                if (tt->xmit_cmd_task(conn, conn->ctask))
+                rc = tt->xmit_cmd_task(conn, conn->ctask);
+                if (rc)
                         goto again;
         }
         /* done with this ctask */
@@ -588,32 +593,34 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                         list_add_tail(&conn->mtask->running,
                                       &conn->mgmt_run_list);
                         spin_unlock_bh(&conn->session->lock);
-                        if (tt->xmit_mgmt_task(conn, conn->mtask))
+                        rc = tt->xmit_mgmt_task(conn, conn->mtask);
+                        if (rc)
                                 goto again;
                 }
                 /* done with this mtask */
                 conn->mtask = NULL;
         }
 
-        return 0;
+        return -ENODATA;
 
 again:
         if (unlikely(conn->suspend_tx))
-                return 0;
+                return -ENODATA;
 
-        return -EAGAIN;
+        return rc;
 }
 
 static void iscsi_xmitworker(void *data)
 {
         struct iscsi_conn *conn = data;
-
+        int rc;
         /*
          * serialize Xmit worker on a per-connection basis.
          */
         mutex_lock(&conn->xmitmutex);
-        if (iscsi_data_xmit(conn))
-                scsi_queue_work(conn->session->host, &conn->xmitwork);
+        do {
+                rc = iscsi_data_xmit(conn);
+        } while (rc >= 0 || rc == -EAGAIN);
         mutex_unlock(&conn->xmitmutex);
 }