From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89FECC282C0 for ; Wed, 23 Jan 2019 18:45:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DF7121855 for ; Wed, 23 Jan 2019 18:45:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726342AbfAWSpK (ORCPT ); Wed, 23 Jan 2019 13:45:10 -0500 Received: from opengridcomputing.com ([72.48.214.68]:50846 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725896AbfAWSpI (ORCPT ); Wed, 23 Jan 2019 13:45:08 -0500 Received: from [10.10.0.239] (cody.ogc.int [10.10.0.239]) by smtp.opengridcomputing.com (Postfix) with ESMTPSA id 7D59F21EC0; Wed, 23 Jan 2019 12:45:07 -0600 (CST) Subject: Re: [PATCH RFC] iw_cxgb4: drop check - dead code To: Jason Gunthorpe , Nicholas Mc Guire Cc: Doug Ledford , Raju Rangoju , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org References: <1547947633-10515-1-git-send-email-hofrat@osadl.org> <20190123183008.GA15698@ziepe.ca> From: Steve Wise Message-ID: <91af1982-e309-476e-cfa4-2f6ef1ee598b@opengridcomputing.com> Date: Wed, 23 Jan 2019 12:45:11 -0600 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190123183008.GA15698@ziepe.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/23/2019 12:30 PM, Jason Gunthorpe wrote: > On Sun, Jan 20, 2019 at 02:27:13AM +0100, Nicholas Mc Guire wrote: >> The kmalloc is called with | __GFP_NOFAIL so there is no point in >> checking the return value - it either returns valid storage or it would >> hang/terminate there. But it is not possible to say if the use of >> __GFP_NOFAIL is really needed and the check should be removed or >> vice-versa (use of __GFP_NOFAIL should be only in exceptional >> cases as I understand it and alloc_srq_queue() is called in quite >> a few places) >> In either way it would need fixing. >> >> Signed-off-by: Nicholas Mc Guire >> Fixes: 6a0b6174d35a ("rdma/cxgb4: Add support for kernel mode SRQ's") >> --- > > Steve? It seems weird to have NOFAIL and then have an error unwind > path, what is the deal here? > >> diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c >> index 917ce5c..c2a12ba 100644 >> --- a/drivers/infiniband/hw/cxgb4/qp.c >> +++ b/drivers/infiniband/hw/cxgb4/qp.c >> @@ -2597,8 +2597,6 @@ static int alloc_srq_queue(struct c4iw_srq *srq, struct c4iw_dev_ucontext *uctx, >> wr_len = sizeof(*res_wr) + sizeof(*res); >> >> skb = alloc_skb(wr_len, GFP_KERNEL | __GFP_NOFAIL); >> - if (!skb) >> - goto err_free_queue; >> set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0); >> >> res_wr = (struct fw_ri_res_wr *)__skb_put(skb, wr_len); >> -- >> 2.1.4 >> The other queue allocations in qp.c don't use __GFP_NOFAIL. So either leave it and remove the error check as per this patch, or remove the NOFAIL and leave the check. I suggest you remove the __GFP_NOFAIL, since I have a recollection that using it was frowned upon. In this case, if there is no memory available it is reasonable to return that error to the user creating the srq... Steve.