Re: [PATCH v2] mtd: rework partitions handling

[Boris Brezillon <bbrezillon@xxxxxxxxxx>]

On Wed, 16 Jan 2019 17:21:44 +0100
Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:

> @@ -457,13 +525,31 @@ int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs);
>  
>  static inline int mtd_suspend(struct mtd_info *mtd)
>  {
> -	return mtd->_suspend ? mtd->_suspend(mtd) : 0;
> +	struct mtd_info *master = mtd_get_master(mtd);
> +	int ret;
> +
> +	if (master->suspended)
> +		return 0;
> +
> +	ret = master->_suspend ? master->_suspend(master) : 0;
> +	if (ret)
> +		return ret;
> +
> +	master->suspended = 1;

It's not entirely clear to me whether dev->suspend() hooks can be
called simultaneously on several CPUs or not, if that's the case, we
should use an atomic_t for the ->suspended field and use the
atomic_add_unless() function when manipulating it.

	if (!atomic_add_unless(&master->suspended, 1, 1))
		return 0;

	ret = master->_suspend ? master->_suspend(master) : 0;
	if (ret) {
		atomic_dec(&master->suspended);
		return ret;
	}

> +	return 0;
>  }
>  
>  static inline void mtd_resume(struct mtd_info *mtd)
>  {
> -	if (mtd->_resume)
> -		mtd->_resume(mtd);
> +	struct mtd_info *master = mtd_get_master(mtd);
> +
> +	if (!master->suspended)
> +		return;
> +
> +	if (master->_resume)
> +		master->_resume(master);
> +
> +	master->suspended = 0;

Same here:

	if (!atomic_add_unless(&master->suspended, -1, 0))
		return;

	if (master->_resume)
		master->_resume(master);
>  }

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