[PATCH v2 6/6] mtd: partitions: support a cleanup callback for parsers
Boris Brezillon
boris.brezillon at free-electrons.com
Fri Dec 4 16:33:37 PST 2015
On Fri, 4 Dec 2015 15:25:18 -0800
Brian Norris <computersforpeace at gmail.com> wrote:
> If partition parsers need to clean up their resources, we shouldn't
> assume that all memory will fit in a single kmalloc() that the caller
> can kfree(). We should allow the parser to provide a proper cleanup
> routine.
>
> Note that this means we need to keep a hold on the parser's module for a
> bit longer, and release it later with mtd_part_parser_put().
>
> Alongside this, define a default callback that we'll automatically use
> if the parser doesn't provide one, so we can still retain the old
> behavior.
>
> Signed-off-by: Brian Norris <computersforpeace at gmail.com>
> ---
> v2:
> * put more common logic in mtd_part_parser_cleanup()
> * provide default cleanup routine (i.e., kfree()) for parsers
>
> drivers/mtd/mtdcore.c | 2 +-
> drivers/mtd/mtdcore.h | 2 ++
> drivers/mtd/mtdpart.c | 35 +++++++++++++++++++++++++++++++++--
> include/linux/mtd/partitions.h | 1 +
> 4 files changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 20b2b38247b6..466cb0da7c08 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -631,7 +631,7 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
> out:
> /* Cleanup any parsed partitions */
> if (parsed.parser)
> - kfree(parsed.parts);
> + mtd_part_parser_cleanup(&parsed);
You can drop the if (parsed.parser) condition: it is already checked in
mtd_part_parser_cleanup().
> return ret;
> }
> EXPORT_SYMBOL_GPL(mtd_device_parse_register);
> diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
> index ce81cc2002f4..55fdb8e1fd2a 100644
> --- a/drivers/mtd/mtdcore.h
> +++ b/drivers/mtd/mtdcore.h
> @@ -17,6 +17,8 @@ int parse_mtd_partitions(struct mtd_info *master, const char * const *types,
> struct mtd_partitions *pparts,
> struct mtd_part_parser_data *data);
>
> +void mtd_part_parser_cleanup(struct mtd_partitions *parts);
> +
> int __init init_mtdchar(void);
> void __exit cleanup_mtdchar(void);
>
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index c5108e0efe88..7ab6b313add4 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -706,10 +706,23 @@ static inline void mtd_part_parser_put(const struct mtd_part_parser *p)
> module_put(p->owner);
> }
>
> +/*
> + * Many partition parsers just expected the core to kfree() all their data in
> + * one chunk. Do that by default.
> + */
> +static void mtd_part_parser_cleanup_default(const struct mtd_partition *pparts,
> + int nr_parts)
> +{
> + kfree(pparts);
> +}
> +
> int __register_mtd_parser(struct mtd_part_parser *p, struct module *owner)
> {
> p->owner = owner;
>
> + if (!p->cleanup)
> + p->cleanup = &mtd_part_parser_cleanup_default;
> +
> spin_lock(&part_parser_lock);
> list_add(&p->list, &part_parsers);
> spin_unlock(&part_parser_lock);
> @@ -753,7 +766,9 @@ static const char * const default_mtd_part_types[] = {
> * This function may return:
> * o a negative error code in case of failure
> * o zero otherwise, and @pparts will describe the partitions, number of
> - * partitions, and the parser which parsed them
> + * partitions, and the parser which parsed them. Caller must release
> + * resources with mtd_part_parser_cleanup() when finished with the returned
> + * data.
> */
> int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
> struct mtd_partitions *pparts,
> @@ -777,7 +792,6 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
> ret = (*parser->parse_fn)(master, &pparts->parts, data);
> pr_debug("%s: parser %s: %i\n",
> master->name, parser->name, ret);
> - mtd_part_parser_put(parser);
> if (ret > 0) {
> printk(KERN_NOTICE "%d %s partitions found on MTD device %s\n",
> ret, parser->name, master->name);
> @@ -785,6 +799,7 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
> pparts->parser = parser;
> return 0;
> }
> + mtd_part_parser_put(parser);
> /*
> * Stash the first error we see; only report it if no parser
> * succeeds
> @@ -795,6 +810,22 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
> return err;
> }
>
> +void mtd_part_parser_cleanup(struct mtd_partitions *parts)
> +{
> + const struct mtd_part_parser *parser;
> +
> + if (!parts)
> + return;
> +
> + parser = parts->parser;
> + if (parser) {
> + if (parser->cleanup)
> + parser->cleanup(parts->parts, parts->nr_parts);
> +
> + mtd_part_parser_put(parser);
> + }
> +}
> +
> int mtd_is_partition(const struct mtd_info *mtd)
> {
> struct mtd_part *part;
> diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
> index cceaf7bd1537..70736e1e6c8f 100644
> --- a/include/linux/mtd/partitions.h
> +++ b/include/linux/mtd/partitions.h
> @@ -71,6 +71,7 @@ struct mtd_part_parser {
> const char *name;
> int (*parse_fn)(struct mtd_info *, const struct mtd_partition **,
> struct mtd_part_parser_data *);
> + void (*cleanup)(const struct mtd_partition *pparts, int nr_parts);
As said in my previous answer, I think it would be more consistent to
have the ->parse_fn() and ->cleanup() methods take an mtd_partitions
pointer.
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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