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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF41DC636D3 for ; Mon, 6 Feb 2023 17:06:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229550AbjBFRGn (ORCPT ); Mon, 6 Feb 2023 12:06:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229537AbjBFRGm (ORCPT ); Mon, 6 Feb 2023 12:06:42 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8AFC22032; Mon, 6 Feb 2023 09:06:40 -0800 (PST) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4P9Xh02LSGz6J9yW; Tue, 7 Feb 2023 01:05:20 +0800 (CST) Received: from localhost (10.81.207.58) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Mon, 6 Feb 2023 17:06:38 +0000 Date: Mon, 6 Feb 2023 17:06:36 +0000 From: Jonathan Cameron To: Dan Williams CC: , , , Subject: Re: [PATCH 06/18] cxl/region: Refactor attach_target() for autodiscovery Message-ID: <20230206170636.0000739e@Huawei.com> In-Reply-To: <167564538227.847146.16305045998592488364.stgit@dwillia2-xfh.jf.intel.com> References: <167564534874.847146.5222419648551436750.stgit@dwillia2-xfh.jf.intel.com> <167564538227.847146.16305045998592488364.stgit@dwillia2-xfh.jf.intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.81.207.58] X-ClientProxiedBy: lhrpeml100002.china.huawei.com (7.191.160.241) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Sun, 05 Feb 2023 17:03:02 -0800 Dan Williams wrote: > Region autodiscovery is the process of kernel creating 'struct > cxl_region' object to represent active CXL memory ranges it finds > already active in hardware when the driver loads. Typically this happens > when platform firmware establishes CXL memory regions and then publishes > them in the memory map. However, this can also happen in the case of > kexec-reboot after the kernel has created regions. > > In the autodiscovery case the region creation process starts with a > known endpoint decoder. Refactor attach_target() into a helper that is > suitable to be called from either sysfs, for runtime region creation, or > from cxl_port_probe() after it has enumerated all endpoint decoders. > > The cxl_port_probe() context is an async device-core probing context, so > it is not appropriate to allow SIGTERM to interrupt the assembly > process. Refactor attach_target() to take @cxled and @state as arguments > where @state indicates whether waiting from the region rwsem is > interruptible or not. As below, I'd have broken this change out as a follow up patch - that way reviewer could check for strict noop refactor, then look in ioslation at that case. I don't care that much though as second patch would only have about 4 lines of diff. Reviewed-by: Jonathan Cameron > > No behavior change is intended. > > Signed-off-by: Dan Williams > --- > drivers/cxl/core/region.c | 47 +++++++++++++++++++++++++++------------------ > 1 file changed, 28 insertions(+), 19 deletions(-) > > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > index 8dea49c021b8..97eafdd75675 100644 > --- a/drivers/cxl/core/region.c > +++ b/drivers/cxl/core/region.c > @@ -1418,31 +1418,25 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled) > up_write(&cxl_region_rwsem); > } > > -static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos) > +static int attach_target(struct cxl_region *cxlr, > + struct cxl_endpoint_decoder *cxled, int pos, > + unsigned int state) > { > - struct device *dev; > - int rc; > - > - dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder); > - if (!dev) > - return -ENODEV; > - > - if (!is_endpoint_decoder(dev)) { > - put_device(dev); > - return -EINVAL; > - } > + int rc = 0; > > - rc = down_write_killable(&cxl_region_rwsem); > + if (state == TASK_INTERRUPTIBLE) > + rc = down_write_killable(&cxl_region_rwsem); > + else > + down_write(&cxl_region_rwsem); I'd be tempted to do this in two hops for patch readability. First make the code reorg then follow up with this bit before the use of it in the next patch. > if (rc) > - goto out; > + return rc; > + > down_read(&cxl_dpa_rwsem); > - rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos); > + rc = cxl_region_attach(cxlr, cxled, pos); > if (rc == 0) > set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags); > up_read(&cxl_dpa_rwsem); > up_write(&cxl_region_rwsem); > -out: > - put_device(dev); > return rc; > } > > @@ -1480,8 +1474,23 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos, > > if (sysfs_streq(buf, "\n")) > rc = detach_target(cxlr, pos); > - else > - rc = attach_target(cxlr, buf, pos); > + else { > + struct device *dev; > + > + dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf); > + if (!dev) > + return -ENODEV; > + > + if (!is_endpoint_decoder(dev)) { > + rc = -EINVAL; > + goto out; > + } > + > + rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos, > + TASK_INTERRUPTIBLE); > +out: > + put_device(dev); > + } > > if (rc < 0) > return rc; > >