IB/uverbs: Fix reference counting on error paths

If an operation fails after incrementing an object's reference count,
then it should decrement the reference count on the error path.

Signed-off-by: Jack Morgenstein <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/core/uverbs_cmd.c

···
 
 err_unreg:
 	ib_dereg_mr(mr);
+	atomic_dec(&pd->usecnt);
 
 err_up:
 	up(&ib_uverbs_idr_mutex);
···
 
 err_destroy:
 	ib_destroy_qp(qp);
+	atomic_dec(&pd->usecnt);
+	atomic_dec(&attr.send_cq->usecnt);
+	atomic_dec(&attr.recv_cq->usecnt);
+	if (attr.srq)
+		atomic_dec(&attr.srq->usecnt);
 
 err_up:
 	up(&ib_uverbs_idr_mutex);
···
 
 err_destroy:
 	ib_destroy_srq(srq);
+	atomic_dec(&pd->usecnt);
 
 err_up:
 	up(&ib_uverbs_idr_mutex);