Delay QP destroy completion until all siw references to QP are dropped. The calling RDMA core will free QP structure after successful return from siw_qp_destroy() call, so siw must not hold any remaining reference to the QP upon return. A use-after-free was encountered in xfstest generic/460, while testing NFSoRDMA. Here, after a TCP connection drop by peer, the triggered siw_cm_work_handler got delayed until after QP destroy call, referencing a QP which has already freed. Fixes: 303ae1cdfdf7 ("rdma/siw: application interface") Reported-by: Olga Kornievskaia <kolga@netapp.com> Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com> Link: https://lore.kernel.org/r/20220920082503.224189-1-bmt@zurich.ibm.com Signed-off-by: Leon Romanovsky <leon@kernel.org>