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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id y6sm2434305pjr.48.2021.06.16.07.41.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 07:41:53 -0700 (PDT) Date: Wed, 16 Jun 2021 07:41:52 -0700 From: Kees Cook To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, Al Viro , gmpy.liaowx@gmail.com, Anton Vorontsov , Colin Cross , Tony Luck , Jonathan Corbet , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , linux-doc@vger.kernel.org, linux-mtd@lists.infradead.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v2 3/4] pstore/blk: Include zone in pstore_device_info Message-ID: <202106160737.B0B8882B@keescook> References: <20210615212121.1200820-1-keescook@chromium.org> <20210615212121.1200820-4-keescook@chromium.org> <20210616040247.GD25873@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210616040247.GD25873@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Jun 16, 2021 at 06:02:47AM +0200, Christoph Hellwig wrote: > > +#define verify_size(name, alignsize, enabled) { \ > > + long _##name_; \ > > + if (enabled) \ > > + _##name_ = check_size(name, alignsize); \ > > + else \ > > + _##name_ = 0; \ > > + /* synchronize visible module parameters to result. */ \ > > + name = _##name_ / 1024; \ > > + dev->zone.name = _##name_; \ > > + } > > The formatting here looks weird between the two-tab indent and the > opening brace on the macro definition line. I can adjust that, sure. > > > - if (!dev || !dev->total_size || !dev->read || !dev->write) { > > + if (!dev || !dev->zone.total_size || !dev->zone.read || !dev->zone.write) { > > if (!dev) > > - pr_err("NULL device info\n"); > > + pr_err("NULL pstore_device_info\n"); > > else { > > - if (!dev->total_size) > > + if (!dev->zone.total_size) > > pr_err("zero sized device\n"); > > - if (!dev->read) > > + if (!dev->zone.read) > > pr_err("no read handler for device\n"); > > - if (!dev->write) > > + if (!dev->zone.write) > > pr_err("no write handler for device\n"); > > } > > This still looks odd to me. Why not the somewhat more verbose but > much more obvious: > > if (!dev) { > pr_err("NULL pstore_device_info\n"); > return -EINVAL; > } > if (!dev->zone.total_size) { > pr_err("zero sized device\n"); > return -EINVAL; > } > ... Will do. > > - dev.total_size = i_size_read(I_BDEV(psblk_file->f_mapping->host)->bd_inode); > > + dev->zone.total_size = i_size_read(I_BDEV(psblk_file->f_mapping->host)->bd_inode); > > This is starting to be unreadable long. A local variable for the inode > might be nice, as that can also be used in the ISBLK check above. Fair enough; will change. > > + if (!pstore_device_info && best_effort && blkdev[0]) { > > + struct pstore_device_info *best_effort_dev; > > + > > + best_effort_dev = kzalloc(sizeof(*best_effort_dev), GFP_KERNEL); > > + if (!best_effort) { > > + ret = -ENOMEM; > > + goto unlock; > > + } > > + best_effort_dev->zone.read = psblk_generic_blk_read; > > + best_effort_dev->zone.write = psblk_generic_blk_write; > > + > > + ret = __register_pstore_blk(best_effort_dev, > > + early_boot_devpath(blkdev)); > > + if (ret) > > + kfree(best_effort_dev); > > + else > > + pr_info("attached %s (%zu) (no dedicated panic_write!)\n", > > + blkdev, best_effort_dev->zone.total_size); > > Maybe split this into a little helper? > > > + /* Unregister and free the best_effort device. */ > > + if (psblk_file) { > > + struct pstore_device_info *dev = pstore_device_info; > > + > > + __unregister_pstore_device(dev); > > + kfree(dev); > > + fput(psblk_file); > > + psblk_file = NULL; > > } > > Same. I guess? I don't feel strongly one way or another. > > > + /* If we've been asked to unload, unregister any registered device. */ > > + if (pstore_device_info) > > + __unregister_pstore_device(pstore_device_info); > > Won't this double unregister pstore_device_info? No, __unregister_pstore_device() will NULL pstore_device_info. > > > struct pstore_device_info { > > - unsigned long total_size; > > unsigned int flags; > > - pstore_zone_read_op read; > > - pstore_zone_write_op write; > > - pstore_zone_erase_op erase; > > - pstore_zone_write_op panic_write; > > + struct pstore_zone_info zone; > > }; > > Given that flags is only used inside of __register_pstore_device > why not kill this struct and just pass it explicitly? Because of the mess pstore's internal APIs used to be. :) It's likely other things will get added here in the future, and I don't want to have to repeat the kind of argument passing games that used to exist in this code. -- Kees Cook