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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 39E12C38A2A for ; Fri, 8 May 2020 13:14:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E3C0206B8 for ; Fri, 8 May 2020 13:14:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729494AbgEHMq4 (ORCPT ); Fri, 8 May 2020 08:46:56 -0400 Received: from smtp2207-205.mail.aliyun.com ([121.197.207.205]:39588 "EHLO smtp2207-205.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729485AbgEHMqz (ORCPT ); Fri, 8 May 2020 08:46:55 -0400 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.07441439|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_system_inform|0.221532-0.00382694-0.774641;FP=0|0|0|0|0|-1|-1|-1;HT=e02c03293;MF=liaoweixiong@allwinnertech.com;NM=1;PH=DS;RN=16;RT=16;SR=0;TI=SMTPD_---.HVGJWfr_1588942007; Received: from 172.16.10.102(mailfrom:liaoweixiong@allwinnertech.com fp:SMTPD_---.HVGJWfr_1588942007) by smtp.aliyun-inc.com(10.147.41.121); Fri, 08 May 2020 20:46:48 +0800 Subject: Re: [PATCH v3 02/11] pstore/blk: new support logger for block devices To: Kees Cook Cc: Anton Vorontsov , Colin Cross , Tony Luck , Jonathan Corbet , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Mauro Carvalho Chehab , Rob Herring , "David S. Miller" , Greg Kroah-Hartman , Jonathan Cameron , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org References: <1585126506-18635-1-git-send-email-liaoweixiong@allwinnertech.com> <1585126506-18635-3-git-send-email-liaoweixiong@allwinnertech.com> <202005072301.57F73B61CC@keescook> From: WeiXiong Liao Message-ID: <6dcadbb0-8720-7973-8b33-747ae0579567@allwinnertech.com> Date: Fri, 8 May 2020 20:46:52 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <202005072301.57F73B61CC@keescook> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org hi Kees Cook, On 2020/5/8 PM 2:07, Kees Cook wrote: > On Wed, Mar 25, 2020 at 04:54:57PM +0800, WeiXiong Liao wrote: >> pstore/blk is similar to pstore/ram, but dump log to block device >> rather than persistent ram. >> [...] >> +int psblk_register_blkdev(unsigned int major, psblk_panic_write_op panic_write) >> +{ >> + struct block_device *bdev; >> + struct psblk_device dev = {0}; >> + struct bdev_info *binfo; >> + int ret = -ENODEV; >> + void *holder = blkdev; >> + >> + binfo = psblk_get_bdev_info(); >> + if (IS_ERR(binfo)) >> + return PTR_ERR(binfo); >> + >> + /* only allow driver matching the @blkdev */ >> + if (!binfo->devt || MAJOR(binfo->devt) != major) { >> + pr_debug("invalid major %u (expect %u)\n", >> + major, MAJOR(binfo->devt)); >> + return -ENODEV; >> + } >> + >> + /* hold bdev exclusively */ >> + bdev = psblk_get_bdev(holder); >> + if (IS_ERR(bdev)) { >> + pr_err("failed to open '%s'!\n", blkdev); >> + return PTR_ERR(bdev); >> + } >> + >> + /* psblk_bdev must be assigned before register to pstore/blk */ >> + psblk_bdev = bdev; >> + blkdev_panic_write = panic_write; >> + >> + dev.total_size = psblk_bdev_size(bdev); >> + dev.panic_write = panic_write ? psblk_blk_panic_write : NULL; >> + dev.read = psblk_generic_blk_read; >> + dev.write = psblk_generic_blk_write; >> + >> + ret = psblk_register_do(&dev); >> + if (ret) >> + goto err_put_bdev; >> + >> + pr_info("using '%s'\n", blkdev); >> + return 0; >> + >> +err_put_bdev: >> + psblk_bdev = NULL; >> + blkdev_panic_write = NULL; >> + psblk_put_bdev(bdev, holder); >> + return ret; >> +} >> +EXPORT_SYMBOL_GPL(psblk_register_blkdev); > > I've gotten this series refactored on top of current pstore, and I've > been making various bikeshed changes to names, etc, and as I went to go > start testing, I realized that nothing actually uses > psblk_register_blkdev(). > > It seems like it should be possible to just start using this on any > block device of the user's choosing. I assume the idea is to allow for > drivers to register panic_write handlers, but even without that, it'd be > nice to just be able to test this with something like /dev/loop0. > Yes. psblk_register_blkdev() is there for block drivers to register panic_write() handlers. The panic_wrire() is used only when panic occurs. Not only the panic log, but also all data on dirty zones. I implement the panic_write() of mmc and nand on the platform of Allwinner, but I think it is not ready to submit to community. All other front-ends but dmesg for panic are available since pstore/blk provides the general write/read through IO stack. That's why /dev/loop0 seemed to works well. > What's your thinking on how this would happen? It seems like if > pstore/blk uses pstore/zone, and mtdpstore uses pstore/blk, there should > be a blkoops that uses pstore/blk too? I guess I need to learn a bit> more about how block device probing works so pstore/blk can notice > devices as they're brought online, etc. > pstore/blk provides all user options and register function for device drivers. The mtdpstore is the implementation case using pstore/blk. How about 'mmc_pstore' for mmc and *_pstore for others block device? I guess I need to learn more about how pstore/blk can notice devices too. I think pstore/blk can be better if block device can do like mtd device that not only notifies but also provides generic panic_write(). -- WeiXiong Liao