scsi: qla2xxx: Always wait for qlt_sess_work_fn() from qlt_stop_phase1()

Currently qlt_stop_phase1() may fail to call flush_scheduled_work(), for
list_empty() may return true as soon as qlt_sess_work_fn() called
list_del(). In order to close this race window, check list_empty() after
calling flush_scheduled_work().

If this patch causes problems, please check commit c4f135d64382
("workqueue: Wrap flush_workqueue() using a macro"). We are on the way to
remove all flush_scheduled_work() calls from the kernel.

Link: https://lore.kernel.org/r/7f24469d-9e39-3398-d851-329b54c0b923@I-love.SAKURA.ne.jp
Tested-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index b170ebbd05b735a15b70c4acc51acd2e2b9cfb40..9013c162d4aa6cc3837c746b9c065eaa7b9f41ec 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -1557,11 +1557,11 @@ int qlt_stop_phase1(struct qla_tgt *tgt)
        ql_dbg(ql_dbg_tgt_mgt, vha, 0xf009,
            "Waiting for sess works (tgt %p)", tgt);
        spin_lock_irqsave(&tgt->sess_work_lock, flags);
-       while (!list_empty(&tgt->sess_works_list)) {
+       do {
                spin_unlock_irqrestore(&tgt->sess_work_lock, flags);
                flush_scheduled_work();
                spin_lock_irqsave(&tgt->sess_work_lock, flags);
-       }
+       } while (!list_empty(&tgt->sess_works_list));
        spin_unlock_irqrestore(&tgt->sess_work_lock, flags);
 
        ql_dbg(ql_dbg_tgt_mgt, vha, 0xf00a,