linux-kernel - Re: [PATCH] nvme: hwmon: fix crash on device teardown

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Date:   Mon, 11 Jan 2021 17:18:57 +0100
From:   Daniel Wagner <dwagner@...e.de>
To:     Hannes Reinecke <hare@...e.de>
Cc:     Enzo Matsumiya <ematsumiya@...e.de>,
        Sagi Grimberg <sagi@...mberg.me>, linux-kernel@...r.kernel.org,
        linux-nvme@...ts.infradead.org, Jens Axboe <axboe@...com>,
        Keith Busch <kbusch@...nel.org>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH] nvme: hwmon: fix crash on device teardown

On Mon, Jan 11, 2021 at 05:00:18PM +0100, Hannes Reinecke wrote:
> Yeah, using the controller node for devm allocations is quite dodgy.
> Does this one help?
> 
> diff --git a/drivers/nvme/host/hwmon.c b/drivers/nvme/host/hwmon.c
> index 6fdd07fb3001..7260af028cf7 100644
> --- a/drivers/nvme/host/hwmon.c
> +++ b/drivers/nvme/host/hwmon.c
> @@ -226,7 +226,7 @@ static const struct hwmon_chip_info
> 
>  int nvme_hwmon_init(struct nvme_ctrl *ctrl)
>  {
> -       struct device *dev = ctrl->dev;
> +       struct device *dev = ctrl->device;

This is what I tried. Yes, it fixes the obvious problem and moves the
hwmon entry under the nvme entry. When the nvme is destroyed, the hwmon
entry is not accessible. But as ctrl->device is not managed by devm the
resources are not freed.