Function cm_work_handler() cannot touch the cm_id after it derefs
it because it might be freed on another concurrent thread.  If there
are more work items queued for this cm_id, then we know there must be
more references because they are added when the work items are queued.
So in the while loop inside cm_work_handler(), after derefing, if the
queue is empty, then exit the function.  Otherwise you know its safe to
re-acquire the lock.

Signed-off-by: Steve Wise <[email protected]>
---

 drivers/infiniband/core/iwcm.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c
index 0bb99bb..c47c203 100644
--- a/drivers/infiniband/core/iwcm.c
+++ b/drivers/infiniband/core/iwcm.c
@@ -878,6 +878,8 @@ static void cm_work_handler(struct work_struct *_work)
                        }
                        return;
                }
+               if (empty)
+                       return;
                spin_lock_irqsave(&cm_id_priv->lock, flags);
        }
        spin_unlock_irqrestore(&cm_id_priv->lock, flags);

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