mtd: partitions: support a cleanup callback for parsers

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@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 20b2b38..89d811e 100644 (file)
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -630,8 +630,7 @@ 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);
        return ret;
 }
 EXPORT_SYMBOL_GPL(mtd_device_parse_register);

diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
index ce81cc2..55fdb8e 100644 (file)
--- 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 53517d7..10bf304 100644 (file)
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -709,10 +709,23 @@ 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);
@@ -756,7 +769,9 @@ 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,
@@ -780,7 +795,6 @@ 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);
@@ -788,6 +802,7 @@ 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
@@ -798,6 +813,22 @@ 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 cceaf7b..70736e1 100644 (file)
--- 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);
 };
 
 /* Container for passing around a set of parsed partitions */