[PATCH v3] mtd: create per-device and module-scope debugfs entries

[Boris Brezillon]

On Wed, 17 May 2017 02:39:24 -0300
"Mario J. Rugiero" <mrugiero at gmail.com> wrote:

> Create a debugfs hierarchy for MTD devices.
> There is one "mtd" dir entry at the root of the debugfs, and one per device
> inside named as the device inside it.
> 
> Signed-off-by: Mario J. Rugiero <mrugiero at gmail.com>


Looks good to me. Maybe you should make it part of your "support
erasing bad blocks" patchset though, because right now it's a bit
unclear to external reviewers (those who did not participate to the
discussion we had in the other thread) why you're adding a debugfs dir
to MTD devs.

Acked-by: Boris Brezillon <boris.brezillon at free-electrons.com>

> ---
> 
> v3: move the changelog out of the commit message
> v2: remove unused macros and add a commit message
> v1: create the debugfs entries
> 
>  drivers/mtd/mtdcore.c   | 17 +++++++++++++++++
>  drivers/mtd/mtdcore.h   |  2 ++
>  include/linux/mtd/mtd.h | 10 ++++++++++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 1517da3ddd7d..461e8139ac2d 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -40,6 +40,7 @@
>  #include <linux/slab.h>
>  #include <linux/reboot.h>
>  #include <linux/leds.h>
> +#include <linux/debugfs.h>
>  
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/partitions.h>
> @@ -662,6 +663,8 @@ static void mtd_set_dev_defaults(struct mtd_info *mtd)
>  	}
>  }
>  
> +static struct dentry *dfs_dir_mtd;
> +
>  /**
>   * mtd_device_parse_register - parse partitions and register an MTD device.
>   *
> @@ -701,6 +704,10 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>  
>  	mtd_set_dev_defaults(mtd);
>  
> +	mtd->dbg.dfs_dir = debugfs_create_dir(mtd->name, dfs_dir_mtd);
> +	if (IS_ERR(mtd->dbg.dfs_dir))
> +		mtd->dbg.dfs_dir = NULL;
> +
>  	memset(&parsed, 0, sizeof(parsed));
>  
>  	ret = parse_mtd_partitions(mtd, types, &parsed, parser_data);
> @@ -740,6 +747,8 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>  out:
>  	/* Cleanup any parsed partitions */
>  	mtd_part_parser_cleanup(&parsed);
> +	if (ret)
> +		debugfs_remove_recursive(mtd->dbg.dfs_dir);
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(mtd_device_parse_register);
> @@ -754,6 +763,8 @@ int mtd_device_unregister(struct mtd_info *master)
>  {
>  	int err;
>  
> +	debugfs_remove_recursive(master->dbg.dfs_dir);
> +
>  	if (master->_reboot)
>  		unregister_reboot_notifier(&master->reboot_notifier);
>  
> @@ -1807,6 +1818,10 @@ static int __init init_mtd(void)
>  
>  	proc_mtd = proc_create("mtd", 0, NULL, &mtd_proc_ops);
>  
> +	dfs_dir_mtd = debugfs_create_dir("mtd", NULL);
> +	if (IS_ERR(dfs_dir_mtd))
> +		dfs_dir_mtd = NULL;
> +
>  	ret = init_mtdchar();
>  	if (ret)
>  		goto out_procfs;
> @@ -1816,6 +1831,7 @@ static int __init init_mtd(void)
>  out_procfs:
>  	if (proc_mtd)
>  		remove_proc_entry("mtd", NULL);
> +	debugfs_remove(dfs_dir_mtd);
>  	bdi_put(mtd_bdi);
>  err_bdi:
>  	class_unregister(&mtd_class);
> @@ -1826,6 +1842,7 @@ static int __init init_mtd(void)
>  
>  static void __exit cleanup_mtd(void)
>  {
> +	debugfs_remove_recursive(dfs_dir_mtd);
>  	cleanup_mtdchar();
>  	if (proc_mtd)
>  		remove_proc_entry("mtd", NULL);
> diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
> index 55fdb8e1fd2a..b5d095d24087 100644
> --- a/drivers/mtd/mtdcore.h
> +++ b/drivers/mtd/mtdcore.h
> @@ -19,6 +19,8 @@ int parse_mtd_partitions(struct mtd_info *master, const char * const *types,
>  
>  void mtd_part_parser_cleanup(struct mtd_partitions *parts);
>  
> +extern struct dentry *debug_mtd;
> +
>  int __init init_mtdchar(void);
>  void __exit cleanup_mtdchar(void);
>  
> diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
> index f8a2ef239c60..6cd0f6b7658b 100644
> --- a/include/linux/mtd/mtd.h
> +++ b/include/linux/mtd/mtd.h
> @@ -206,6 +206,15 @@ struct mtd_pairing_scheme {
>  
>  struct module;	/* only needed for owner field in mtd_info */
>  
> +/**
> + * struct mtd_debug_info - debugging information for an MTD device.
> + *
> + * @dfs_dir: direntry object of the MTD device debugfs directory
> + */
> +struct mtd_debug_info {
> +	struct dentry *dfs_dir;
> +};
> +
>  struct mtd_info {
>  	u_char type;
>  	uint32_t flags;
> @@ -346,6 +355,7 @@ struct mtd_info {
>  	struct module *owner;
>  	struct device dev;
>  	int usecount;
> +	struct mtd_debug_info dbg;
>  };
>  
>  int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,