IB/core: Protect against self-requeue of a cq work item

We need to make sure that the cq work item does not
run when we are destroying the cq. Unlike flush_work,
cancel_work_sync protects against self-requeue of the
work item (which we can do in ib_cq_poll_work).

Signed-off-by: Sagi Grimberg <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>--
Reviewed-by: Leon Romanovsky <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>

drivers/infiniband/core/cq.c

@@ -196,7 +196,7 @@ void ib_free_cq(struct ib_cq *cq)
 		irq_poll_disable(&cq->iop);
 		break;
 	case IB_POLL_WORKQUEUE:
-		flush_work(&cq->work);
+		cancel_work_sync(&cq->work);
 		break;
 	default:
 		WARN_ON_ONCE(1);