[PATCH 1/3] csiostor: fix completion usage

From: Daniel Wagner
Date: Tue Sep 13 2016 - 04:59:08 EST


From: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>

The (re)initialzing of the completion object should be done before we
trigger the transfer. Doing this after triggering the hardware opens up
a race window. Without the timeout we would problaly even deadlock. Use
also reinit_completion because we initalize the whole data structure in
csio_scscim_init().

There is only one waiter for the completion, therefore there is no need
to use complete_all(). Let's make that clear by using complete() instead
of complete_all().

The usage pattern of the completion is:

waiter context waker context

csio_eh_abort_handler()
reinit_completion()
wait_for_completion_timeout()

csio_scsi_err_handler()
complete()

Signed-off-by: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
---
drivers/scsi/csiostor/csio_scsi.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/csiostor/csio_scsi.c b/drivers/scsi/csiostor/csio_scsi.c
index c2a6f9f..89a52b9 100644
--- a/drivers/scsi/csiostor/csio_scsi.c
+++ b/drivers/scsi/csiostor/csio_scsi.c
@@ -1721,7 +1721,7 @@ csio_scsi_err_handler(struct csio_hw *hw, struct csio_ioreq *req)

/* Wake up waiting threads */
csio_scsi_cmnd(req) = NULL;
- complete_all(&req->cmplobj);
+ complete(&req->cmplobj);
}

/*
@@ -1945,6 +1945,7 @@ csio_eh_abort_handler(struct scsi_cmnd *cmnd)
ready = csio_is_lnode_ready(ln);
tmo = CSIO_SCSI_ABRT_TMO_MS;

+ reinit_completion(&ioreq->cmplobj);
spin_lock_irq(&hw->lock);
rv = csio_do_abrt_cls(hw, ioreq, (ready ? SCSI_ABORT : SCSI_CLOSE));
spin_unlock_irq(&hw->lock);
@@ -1964,8 +1965,6 @@ csio_eh_abort_handler(struct scsi_cmnd *cmnd)
goto inval_scmnd;
}

- /* Wait for completion */
- init_completion(&ioreq->cmplobj);
wait_for_completion_timeout(&ioreq->cmplobj, msecs_to_jiffies(tmo));

/* FW didnt respond to abort within our timeout */
--
2.7.4