Re: [PATCH 1/2] mm:zpool: constify struct zpool type

From: Sergey Senozhatsky
Date: Fri Sep 11 2015 - 20:30:33 EST


On (09/11/15 15:21), Andrew Morton wrote:
> > From: Sergey SENOZHATSKY <sergey.senozhatsky@xxxxxxxxx>
> >
> > Constify `struct zpool' ->type.
> >
>
> I think I prefer Dan's patch, which deletes stuff:

Sure, agree. Somehow I overlooked it.

-ss


> From: Dan Streetman <ddstreet@xxxxxxxx>
> Subject: zpool: remove redundant zpool->type string, const-ify zpool_get_type
>
> Make the return type of zpool_get_type const; the string belongs to the
> zpool driver and should not be modified. Remove the redundant type field
> in the struct zpool; it is private to zpool.c and isn't needed since
> ->driver->type can be used directly. Add comments indicating strings must
> be null-terminated.
>
> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> include/linux/zpool.h | 2 +-
> mm/zpool.c | 14 ++++++++------
> 2 files changed, 9 insertions(+), 7 deletions(-)
>
> diff -puN include/linux/zpool.h~zpool-remove-redundant-zpool-type-string-const-ify-zpool_get_type include/linux/zpool.h
> --- a/include/linux/zpool.h~zpool-remove-redundant-zpool-type-string-const-ify-zpool_get_type
> +++ a/include/linux/zpool.h
> @@ -41,7 +41,7 @@ bool zpool_has_pool(char *type);
> struct zpool *zpool_create_pool(char *type, char *name,
> gfp_t gfp, const struct zpool_ops *ops);
>
> -char *zpool_get_type(struct zpool *pool);
> +const char *zpool_get_type(struct zpool *pool);
>
> void zpool_destroy_pool(struct zpool *pool);
>
> diff -puN mm/zpool.c~zpool-remove-redundant-zpool-type-string-const-ify-zpool_get_type mm/zpool.c
> --- a/mm/zpool.c~zpool-remove-redundant-zpool-type-string-const-ify-zpool_get_type
> +++ a/mm/zpool.c
> @@ -18,8 +18,6 @@
> #include <linux/zpool.h>
>
> struct zpool {
> - char *type;
> -
> struct zpool_driver *driver;
> void *pool;
> const struct zpool_ops *ops;
> @@ -73,6 +71,7 @@ int zpool_unregister_driver(struct zpool
> }
> EXPORT_SYMBOL(zpool_unregister_driver);
>
> +/* this assumes @type is null-terminated. */
> static struct zpool_driver *zpool_get_driver(char *type)
> {
> struct zpool_driver *driver;
> @@ -113,6 +112,8 @@ static void zpool_put_driver(struct zpoo
> * not be loaded, and calling @zpool_create_pool() with the pool type will
> * fail.
> *
> + * The @type string must be null-terminated.
> + *
> * Returns: true if @type pool is available, false if not
> */
> bool zpool_has_pool(char *type)
> @@ -145,6 +146,8 @@ EXPORT_SYMBOL(zpool_has_pool);
> *
> * Implementations must guarantee this to be thread-safe.
> *
> + * The @type and @name strings must be null-terminated.
> + *
> * Returns: New zpool on success, NULL on failure.
> */
> struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
> @@ -174,7 +177,6 @@ struct zpool *zpool_create_pool(char *ty
> return NULL;
> }
>
> - zpool->type = driver->type;
> zpool->driver = driver;
> zpool->pool = driver->create(name, gfp, ops, zpool);
> zpool->ops = ops;
> @@ -208,7 +210,7 @@ struct zpool *zpool_create_pool(char *ty
> */
> void zpool_destroy_pool(struct zpool *zpool)
> {
> - pr_debug("destroying pool type %s\n", zpool->type);
> + pr_debug("destroying pool type %s\n", zpool->driver->type);
>
> spin_lock(&pools_lock);
> list_del(&zpool->list);
> @@ -228,9 +230,9 @@ void zpool_destroy_pool(struct zpool *zp
> *
> * Returns: The type of zpool.
> */
> -char *zpool_get_type(struct zpool *zpool)
> +const char *zpool_get_type(struct zpool *zpool)
> {
> - return zpool->type;
> + return zpool->driver->type;
> }
>
> /**
> _
>
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