linux-kernel - Re: [PATCH v2 2/9] block: partitions: populate fwnode

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Date: Thu, 13 Jun 2024 23:09:55 +0200
From: Hauke Mehrtens <hauke@...ke-m.de>
To: Daniel Golle <daniel@...rotopia.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
 Jens Axboe <axboe@...nel.dk>,
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
 Dave Chinner <dchinner@...hat.com>, Jan Kara <jack@...e.cz>,
 Christian Brauner <brauner@...nel.org>,
 Thomas Weißschuh <linux@...ssschuh.net>,
 Al Viro <viro@...iv.linux.org.uk>, Li Lingfeng <lilingfeng3@...wei.com>,
 Christian Heusel <christian@...sel.eu>, Min Li <min15.li@...sung.com>,
 Avri Altman <avri.altman@....com>, Adrian Hunter <adrian.hunter@...el.com>,
 Hannes Reinecke <hare@...e.de>, Mikko Rapeli <mikko.rapeli@...aro.org>,
 Yeqi Fu <asuk4.q@...il.com>, Victor Shih <victor.shih@...esyslogic.com.tw>,
 Christophe JAILLET <christophe.jaillet@...adoo.fr>,
 Li Zhijian <lizhijian@...itsu.com>,
 "Ricardo B. Marliere" <ricardo@...liere.net>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
 linux-block@...r.kernel.org
Subject: Re: [PATCH v2 2/9] block: partitions: populate fwnode

Hi Daniel,

On 5/30/24 04:13, Daniel Golle wrote:
> Let block partitions to be represented by a firmware node and hence
> allow them to being referenced e.g. for use with blk-nvmem.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>   block/partitions/core.c | 41 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 41 insertions(+)
> 
> diff --git a/block/partitions/core.c b/block/partitions/core.c
> index ab76e64f0f6c..93d109409905 100644
> --- a/block/partitions/core.c
> +++ b/block/partitions/core.c
> @@ -10,6 +10,8 @@
>   #include <linux/ctype.h>
>   #include <linux/vmalloc.h>
>   #include <linux/raid/detect.h>
> +#include <linux/property.h>
> +
>   #include "check.h"
>   
>   static int (*const check_part[])(struct parsed_partitions *) = {
> @@ -281,6 +283,43 @@ static ssize_t whole_disk_show(struct device *dev,
>   }
>   static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
>   
> +static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
> +{
> +	struct fwnode_handle *fw_parts, *fw_part;
> +	struct device *ddev = disk_to_dev(bdev->bd_disk);
> +	const char *partname, *uuid;
> +	u32 partno;
> +
> +	fw_parts = device_get_named_child_node(ddev, "partitions");
> +	if (!fw_parts)
> +		fw_parts = device_get_named_child_node(ddev->parent, "partitions");

Could you please explain why you try to get the node from the device and 
the parent when it is not available? I think this should go into the 
commit description.

> +
> +	if (!fw_parts)
> +		return NULL;
> +
> +	fwnode_for_each_child_node(fw_parts, fw_part) {
> +		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
> +		    (!bdev->bd_meta_info || strncmp(uuid,
> +						    bdev->bd_meta_info->uuid,
> +						    PARTITION_META_INFO_UUIDLTH)))

I think you should check that the uuid provided in the device tree is 
not longer than PARTITION_META_INFO_UUIDLTH. Same for the volume name.

> +			continue;
> +
> +		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
> +		    (!bdev->bd_meta_info || strncmp(partname,
> +						    bdev->bd_meta_info->volname,
> +						    PARTITION_META_INFO_VOLNAMELTH)))
> +			continue;
> +
> +		if (!fwnode_property_read_u32(fw_part, "partno", &partno) &&
> +		    bdev_partno(bdev) != partno)
> +			continue;
> +
> +		return fw_part;
> +	}
> +
> +	return NULL;
> +}
> +
>   /*
>    * Must be called either with open_mutex held, before a disk can be opened or
>    * after all disk users are gone.
> @@ -355,6 +394,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
>   			goto out_put;
>   	}
>   
> +	device_set_node(pdev, find_partition_fwnode(bdev));
> +
>   	/* delay uevent until 'holders' subdir is created */
>   	dev_set_uevent_suppress(pdev, 1);
>   	err = device_add(pdev);

Hauke