linux-kernel - Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while in suspend

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Message-ID: <63be9121-18c3-1ef2-c448-f99fb861490f@samsung.com>
Date:   Mon, 29 Nov 2021 12:17:16 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Sean Nyekjaer <sean@...nix.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Boris Brezillon <boris.brezillon@...labora.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while
 in suspend

Hi Sean,

On 29.11.2021 10:41, Sean Nyekjaer wrote:
> On Mon, Nov 29, 2021 at 10:19:08AM +0100, Miquel Raynal wrote:
>> boris.brezillon@...labora.com wrote on Tue, 23 Nov 2021 14:07:15 +0100:
>>> On Tue, 23 Nov 2021 13:50:12 +0100
>>> Sean Nyekjaer <sean@...nix.com> wrote:
>>>> @Boris do we need to do something similar here to what we did with the
>>>> mtdconcat stuff?
>>> Absolutely, physmasp subdevices are never initialized/registered, so
>>> you can't call any of the mtd helpers taking the suspend lock on those.
>>> I guess it'd be better to call mtd_suspend/resume() on the concat device
>>> in though:
>> Any chance that you will come up with a fix or v6 of the series anytime
>> soon?
>>
>>> static void physmap_flash_shutdown(struct platform_device *dev)
>>> {
>>> 	struct physmap_flash_info *info = platform_get_drvdata(dev);
>>>
>>> 	mtd_suspend(info->cmtd);
>>> }
>>
>> Thanks,
>> Miquèl
> Hi Miquèl,
>
> I'm not 100% comfortable in doing this.
>
> During this patch series I have mostly been Boris' tester and
> implemented his ideas :/
>
> I'm willing to give it a try, if Marek shares how to reproduce this with qemu :)

Frankly speaking there is nothing special in my setup, typical options 
to run ARM64/virt machine. Just run recent qemu (I did my test with 
5.2.0) with any basic arm/arm64 rootfs (I've used Debian). The qemu 
command line (copied somewhere from the Internet) I've used is:

qemu-system-aarch64 -serial stdio -monitor null -kernel Image -append 
"console=ttyAMA0 root=/dev/vda rootwait" -M virt -cpu cortex-a57 -smp 2 
-m 1024 -device virtio-blk-device,drive=virtio-blk0 -drive 
file=qemu-virt-rootfs.raw,id=virtio-blk0,if=none,format=raw -netdev 
user,id=user -device virtio-net-device,netdev=user -display none

Once it boots to shell, just type 'reboot' and wait until issue appears.

Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland