Re: [PATCH v1 00/11] pstore: support crash log to block and mtd device

From: Kees Cook <keescook@chromium.org>
To: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Cc: Anton Vorontsov <anton@enomsg.org>,
	Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Rob Herring <robh@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mtd@lists.infradead.org
Subject: Re: [PATCH v1 00/11] pstore: support crash log to block and mtd device
Date: Thu, 6 Feb 2020 01:13:08 -0800	[thread overview]
Message-ID: <202002060108.7389A4C@keescook> (raw)
In-Reply-To: <1579482233-2672-1-git-send-email-liaoweixiong@allwinnertech.com>

On Mon, Jan 20, 2020 at 09:03:42AM +0800, WeiXiong Liao wrote:
> Why do we need to log to block (mtd) device?
> 1. Most embedded intelligent equipment have no persistent ram, which
>    increases costs. We perfer to cheaper solutions, like block devices.
> 2. Do not any equipment have battery, which means that it lost all data
>    on general ram if power failure. Pstore has little to do for these
>    equipments.
> 
> Why do we need mtdpstore instead of mtdoops?
> 1. repetitive jobs between pstore and mtdoops
>    Both of pstore and mtdoops do the same jobs that store panic/oops log.
> 2. do what a driver should do
>    To me, a driver should provide methods instead of policies. What MTD
>    should do is to provide read/write/erase operations, geting rid of codes
>    about chunk management, kmsg dumper and configuration.
> 3. enhanced feature
>    Not only store log, but also show it as files.
>    Not only log, but also trigger time and trigger count.
>    Not only panic/oops log, but also log recorder for pmsg, console and
>    ftrace in the future.

Hi! Sorry for the delay in my review of this series -- it's been a busy
couple of weeks for me. :) I'm still travelling this week, but I want to
give this a good review. I really like the idea of having a block device
backend for pstore; I'm excited to get this feature landed.

I think there may be a lot of redundancy between ramoops and the block
code in this series, but I suspect the refactoring of that can happen at
a later time. I'd like to get this reviewed and tested and see if I can
land it in the v5.7 merge window.

I hope to have time to focus on this next week once I'm back in my
normal timezone. ;)

Thanks again!

-Kees

-- 
Kees Cook