Re: [PATCH 2/2] sysfs: add devm_sysfs_create_group() and friends

[Dmitry Torokhov]

On Sun, Feb 12, 2017 at 04:36:19PM -0800, Dmitry Torokhov wrote:
> Many drivers create additional driver-specific device attributes when
> binding to the device and providing managed version of sysfs_create_group()
> will simplify unbinding and error handling in probe path for such drivers.
> 
> Without managed version driver writers either have to mix manual and
> managed resources, which is prone to errors, or open-code this function by
> providing a wrapper to sysfs_create_group() and use it with
> devm_add_action() or devm_add_action_or_reset().
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---

Greg, gentle ping...


>  fs/sysfs/group.c      | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/sysfs.h |  10 ++++
>  2 files changed, 134 insertions(+)
> 
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index ac2de0ed69ad..24fc205fcb9b 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -13,6 +13,7 @@
>  #include <linux/kobject.h>
>  #include <linux/module.h>
>  #include <linux/dcache.h>
> +#include <linux/device.h>
>  #include <linux/namei.h>
>  #include <linux/err.h>
>  #include "sysfs.h"
> @@ -409,3 +410,126 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  	return IS_ERR(link) ? PTR_ERR(link) : 0;
>  }
>  EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
> +
> +struct sysfs_group_devres {
> +	const struct attribute_group *group;
> +};
> +
> +static int devm_sysfs_group_match(struct device *dev, void *res, void *data)
> +{
> +	return ((struct sysfs_group_devres *)res)->group == data;
> +}
> +
> +static void devm_sysfs_group_remove_group(struct device *dev, void *res)
> +{
> +	struct sysfs_group_devres *devres = res;
> +	const struct attribute_group *group = devres->group;
> +
> +	dev_dbg(dev, "%s: removing group %p\n", __func__, group);
> +	sysfs_remove_group(&dev->kobj, group);
> +}
> +
> +/**
> + * devm_sysfs_create_group - given a device, create a managed attribute group
> + * @dev:	The device to create the group for
> + * @grp:	The attribute group to create
> + *
> + * This function creates a group for the first time.  It will explicitly
> + * warn and error if any of the attribute files being created already exist.
> + *
> + * Returns 0 on success or error code on failure.
> + */
> +int devm_sysfs_create_group(struct device *dev,
> +			    const struct attribute_group *grp)
> +{
> +	struct sysfs_group_devres *devres;
> +	int error;
> +
> +	devres = devres_alloc(devm_sysfs_group_remove_group,
> +			      sizeof(*devres), GFP_KERNEL);
> +	if (!devres)
> +		return -ENOMEM;
> +
> +	error = sysfs_create_group(&dev->kobj, grp);
> +	if (error) {
> +		devres_free(devres);
> +		return error;
> +	}
> +
> +	devres_add(dev, devres);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_sysfs_create_group);
> +
> +/**
> + * devm_sysfs_create_groups - create a bunch of managed attribute groups
> + * @dev:	The device to create the group for
> + * @groups:	The attribute groups to create, NULL terminated
> + *
> + * This function creates a bunch of managed attribute groups.  If an error
> + * occurs when creating a group, all previously created groups will be
> + * removed, unwinding everything back to the original state when this
> + * function was called.  It will explicitly warn and error if any of the
> + * attribute files being created already exist.
> + *
> + * Returns 0 on success or error code from sysfs_create_group on failure.
> + */
> +int devm_sysfs_create_groups(struct device *dev,
> +			     const struct attribute_group **groups)
> +{
> +	int error;
> +	int i;
> +
> +	if (!groups)
> +		return 0;
> +
> +	for (i = 0; groups[i]; i++) {
> +		error = devm_sysfs_create_group(dev, groups[i]);
> +		if (error) {
> +			while (--i >= 0)
> +				devm_sysfs_remove_group(dev, groups[i]);
> +			return error;
> +		}
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_sysfs_create_groups);
> +
> +/**
> + * devm_sysfs_remove_group: remove a managed group from a device
> + * @dev:	device to remove the group from
> + * @grp:	group to remove
> + *
> + * This function removes a group of attributes from a device.  The attributes
> + * previously have to have been created for this group, otherwise it will fail.
> + */
> +void devm_sysfs_remove_group(struct device *dev,
> +			     const struct attribute_group *grp)
> +{
> +	WARN_ON(devres_release(dev, devm_sysfs_group_remove_group,
> +			       devm_sysfs_group_match,
> +			       /* cast away const */ (void *)grp));
> +}
> +EXPORT_SYMBOL_GPL(devm_sysfs_remove_group);
> +
> +/**
> + * devm_sysfs_remove_groups - remove a list of managed groups
> + *
> + * @dev:	The device for the groups to be removed from
> + * @groups:	NULL terminated list of groups to be removed
> + *
> + * If groups is not NULL, remove the specified groups from the device.
> + */
> +void devm_sysfs_remove_groups(struct device *dev,
> +			      const struct attribute_group **groups)
> +{
> +	int i;
> +
> +	if (!groups)
> +		return;
> +
> +	for (i = 0; groups[i]; i++)
> +		devm_sysfs_remove_group(dev, groups[i]);
> +}
> +EXPORT_SYMBOL_GPL(devm_sysfs_remove_groups);
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index c6f0f0d0e17e..d9a5b8aab0e2 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -282,6 +282,16 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  				      struct kobject *target_kobj,
>  				      const char *target_name);
>  
> +struct device;
> +int __must_check devm_sysfs_create_group(struct device *dev,
> +				const struct attribute_group *grp);
> +int __must_check devm_sysfs_create_groups(struct device *dev,
> +				const struct attribute_group **groups);
> +void devm_sysfs_remove_group(struct device *dev,
> +			     const struct attribute_group *grp);
> +void devm_sysfs_remove_groups(struct device *dev,
> +			      const struct attribute_group **groups);
> +
>  void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
>  
>  int __must_check sysfs_init(void);
> -- 
> 2.11.0.483.g087da7b7c-goog
> 

-- 
Dmitry