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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 440C0C4332D for ; Fri, 22 Jan 2021 11:01:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EEFE2239EE for ; Fri, 22 Jan 2021 11:01:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727845AbhAVK5z convert rfc822-to-8bit (ORCPT ); Fri, 22 Jan 2021 05:57:55 -0500 Received: from szxga03-in.huawei.com ([45.249.212.189]:2870 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727280AbhAVJ2Y (ORCPT ); Fri, 22 Jan 2021 04:28:24 -0500 Received: from DGGEMM402-HUB.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4DMYHK6HXsz5FF4; Fri, 22 Jan 2021 17:04:45 +0800 (CST) Received: from dggema703-chm.china.huawei.com (10.3.20.67) by DGGEMM402-HUB.china.huawei.com (10.3.20.210) with Microsoft SMTP Server (TLS) id 14.3.498.0; Fri, 22 Jan 2021 17:06:12 +0800 Received: from dggema753-chm.china.huawei.com (10.1.198.195) by dggema703-chm.china.huawei.com (10.3.20.67) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Fri, 22 Jan 2021 17:06:11 +0800 Received: from dggema753-chm.china.huawei.com ([10.9.48.84]) by dggema753-chm.china.huawei.com ([10.9.48.84]) with mapi id 15.01.2106.002; Fri, 22 Jan 2021 17:06:11 +0800 From: liweihang To: Jason Gunthorpe CC: Leon Romanovsky , "dledford@redhat.com" , "linux-rdma@vger.kernel.org" , "linuxarm@openeuler.org" Subject: Re: [PATCH RFC 1/7] RDMA/hns: Introduce DCA for RC QP Thread-Topic: [PATCH RFC 1/7] RDMA/hns: Introduce DCA for RC QP Thread-Index: AQHW7/oITeBBndE4CkiFjIHgF/TJug== Date: Fri, 22 Jan 2021 09:06:11 +0000 Message-ID: <0afb522df2d24fe3be8d7ee2611465ef@huawei.com> References: <1610706138-4219-1-git-send-email-liweihang@huawei.com> <1610706138-4219-2-git-send-email-liweihang@huawei.com> <20210120081025.GA225873@unreal> <8d255812177a4f53becd3c912d00c528@huawei.com> <20210121085325.GC320304@unreal> <96d7fb7db36e4bce8c556d0de5c8f961@huawei.com> <20210121133445.GY4147@nvidia.com> <14243f680ba6428789b878078f766967@huawei.com> <20210121135143.GZ4147@nvidia.com> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.67.100.165] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 2021/1/21 21:52, Jason Gunthorpe wrote: > On Thu, Jan 21, 2021 at 01:48:56PM +0000, liweihang wrote: >> On 2021/1/21 21:36, Jason Gunthorpe wrote: >>> On Thu, Jan 21, 2021 at 01:33:42PM +0000, liweihang wrote: >>> >>>> We need to allocate memory while spin_lock is hold, how about using GFP_KERNEL or >>>> GFP_NOWAIT? >>> >>> You should try hard not to do that. Convert he spinlock to a mutex, >>> for instance. >>> >>> Jason >>> >> >> But what if some kernel users call ib_post_send() when holding a spinlock? > > I doubt extensions like this would be part of kernel verbs.. > > Does any ULP call ib_post_send under lock? I'm not sure that is valid. > > Jason > I didn't find such a ULP calling ib_post_send in a spinlock either. Anyway, I will use GFP_NOWAIT instead of GFP_ATOMIC. Thanks Weihang