[SCSI] libiscsi: fix cmd timeout/completion race

If the driver/lib has called scsi_done and cleaned up internally but
scsi layer has not yet called blk_mark_rq_complete when the command
times out we hit a problem if the timeout code calls blk_mark_rq_complete first.
When the time out code calls into the driver we were returning
BLK_EH_RESET_TIMER and that causes the timeout code to just call
us again later.

We need to be calling BLK_EH_HANDLED so the timeout code can complete
the completion process because it had called blk_mark_rq_complete
on the command and now owns its processing.

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

1 files changed, 10 insertions, 10 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 8582d7c25732..82c3fd4bc938 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -1909,6 +1909,16 @@ static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
         ISCSI_DBG_EH(session, "scsi cmd %p timedout\n", sc);
 
         spin_lock(&session->lock);
+        task = (struct iscsi_task *)sc->SCp.ptr;
+        if (!task) {
+                /*
+                 * Raced with completion. Blk layer has taken ownership
+                 * so let timeout code complete it now.
+                 */
+                rc = BLK_EH_HANDLED;
+                goto done;
+        }
+
         if (session->state != ISCSI_STATE_LOGGED_IN) {
                 /*
                  * We are probably in the middle of iscsi recovery so let
@@ -1925,16 +1935,6 @@ static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
                 goto done;
         }
 
-        task = (struct iscsi_task *)sc->SCp.ptr;
-        if (!task) {
-                /*
-                 * Raced with completion. Just reset timer, and let it
-                 * complete normally
-                 */
-                rc = BLK_EH_RESET_TIMER;
-                goto done;
-        }
-
         /*
          * If we have sent (at least queued to the network layer) a pdu or
          * recvd one for the task since the last timeout ask for