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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 BFDFDC282C0 for ; Thu, 24 Jan 2019 01:54:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96DC42184C for ; Thu, 24 Jan 2019 01:54:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727128AbfAXByN (ORCPT ); Wed, 23 Jan 2019 20:54:13 -0500 Received: from 178.115.242.59.static.drei.at ([178.115.242.59]:36604 "EHLO mail.osadl.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726310AbfAXByN (ORCPT ); Wed, 23 Jan 2019 20:54:13 -0500 Received: by mail.osadl.at (Postfix, from userid 1001) id 4CB4A5C0FB6; Thu, 24 Jan 2019 02:53:52 +0100 (CET) Date: Thu, 24 Jan 2019 02:53:52 +0100 From: Nicholas Mc Guire To: Steve Wise Cc: Jason Gunthorpe , Nicholas Mc Guire , Doug Ledford , Raju Rangoju , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] iw_cxgb4: drop check - dead code Message-ID: <20190124015352.GA30939@osadl.at> References: <1547947633-10515-1-git-send-email-hofrat@osadl.org> <20190123183008.GA15698@ziepe.ca> <91af1982-e309-476e-cfa4-2f6ef1ee598b@opengridcomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <91af1982-e309-476e-cfa4-2f6ef1ee598b@opengridcomputing.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 23, 2019 at 12:45:11PM -0600, Steve Wise wrote: > > > 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... > thanks for taking care of this - I simply did not have enough context to decide if there would be some special reason for this allocation to need __GFP_NOFAIL - keeping its use to a minimum though is the best solution. thx! hofrat