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 C6BACC433EF for ; Tue, 1 Feb 2022 22:32:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241196AbiBAWcA (ORCPT ); Tue, 1 Feb 2022 17:32:00 -0500 Received: from mga14.intel.com ([192.55.52.115]:9959 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234823AbiBAWcA (ORCPT ); Tue, 1 Feb 2022 17:32:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643754720; x=1675290720; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=VfsPPIa+HxLve6T7db4qBLlpdJ1WsNzzpYMJWjKmpdQ=; b=NHVCqOzg5FQ7DCOJibuxndoM/yz4Ha076PCJzl+PkebvNQOYvZU9qqXL kf0++v7MAErmbHQnJQtUFX2TVDYrdB5BdEWOwLIYYLlbucmNTZKO7830M idFZw7tQXOPlSf+SSPskIeTammbiN8c7tbr8gDM3pZ2ngjlJ/1mW1bAJH 5bJh+tpA1n9Qq4ExXHOdHslAk0cXGtSt3rURoTed3W3jvn/in8/PEnhiR Pn/6wZKLzd3fq2rxecvMi9oaB8jcRrjnNhH9RWx96909iCH/pmtr+iF0Z CMmMuKhD3tfRX8xw6SWu8lTc8h012vkmk3ha192IsoO31S0HCNbkqCOLO A==; X-IronPort-AV: E=McAfee;i="6200,9189,10245"; a="248030450" X-IronPort-AV: E=Sophos;i="5.88,335,1635231600"; d="scan'208";a="248030450" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Feb 2022 14:32:00 -0800 X-IronPort-AV: E=Sophos;i="5.88,335,1635231600"; d="scan'208";a="523233826" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Feb 2022 14:31:59 -0800 Date: Tue, 1 Feb 2022 14:31:59 -0800 From: Ira Weiny To: Ben Widawsky Cc: Dan Williams , Jonathan Cameron , Bjorn Helgaas , Alison Schofield , Vishal Verma , linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH V6 09/10] cxl/mem: Retry reading CDAT on failure Message-ID: <20220201223159.GQ785175@iweiny-DESK2.sc.intel.com> Mail-Followup-To: Ben Widawsky , Dan Williams , Jonathan Cameron , Bjorn Helgaas , Alison Schofield , Vishal Verma , linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org References: <20220201071952.900068-1-ira.weiny@intel.com> <20220201071952.900068-10-ira.weiny@intel.com> <20220201185928.ffdgvnn6mcmo7by7@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220201185928.ffdgvnn6mcmo7by7@intel.com> User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Feb 01, 2022 at 10:59:28AM -0800, Widawsky, Ben wrote: > On 22-01-31 23:19:51, ira.weiny@intel.com wrote: > > From: Ira Weiny > > > > The CDAT read may fail for a number of reasons but mainly it is possible > > to get different parts of a valid state. The checksum in the CDAT table > > protects against this. > > > > Now that the checksum is validated issue a retry if the CDAT read fails. > > For now 2 retries are implemented. > > > > Signed-off-by: Ira Weiny > > > > --- > > NOTE: Is 2 enough? Should this just be delayed until the time when the > > data is actually needed and not there? > > I can't speak to retries at all, but one small issue below. It might make sense > if we keep this to make it a modparam. Not a bad idea. > > > > > Changes from V5: > > New patch -- easy to push off or drop. > > --- > > drivers/cxl/core/memdev.c | 17 ++++++++++++++++- > > 1 file changed, 16 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c > > index a01068e98333..11d721c56f08 100644 > > --- a/drivers/cxl/core/memdev.c > > +++ b/drivers/cxl/core/memdev.c > > @@ -356,7 +356,8 @@ static const struct file_operations cxl_memdev_fops = { > > .llseek = noop_llseek, > > }; > > > > -static int read_cdat_data(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds) > > +static int __read_cdat_data(struct cxl_memdev *cxlmd, > > + struct cxl_dev_state *cxlds) > > { > > struct device *dev = &cxlmd->dev; > > size_t cdat_length; > > @@ -371,6 +372,20 @@ static int read_cdat_data(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds) > > return cxl_mem_cdat_read_table(cxlds, &cxlmd->cdat); > > } > > > > +static int read_cdat_data(struct cxl_memdev *cxlmd, > > + struct cxl_dev_state *cxlds) > > +{ > > + int retries = 2; > > + int rc; > > + > > + while (--retries) { > > You either want retries--, or retries = 3... Opps yea. Thanks, Ira > > > + rc = __read_cdat_data(cxlmd, cxlds); > > + if (!rc) > > + break; > > + } > > + return rc; > > +} > > + > > struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds) > > { > > struct cxl_memdev *cxlmd; > > -- > > 2.31.1 > >