2019-03-25 12:53:01

by Arnd Bergmann

Subject: [PATCH] [v2] ceph: fix clang warning for CEPH_DEFINE_OID_ONSTACK

clang complains about assigning a variable to itself during the
declaration:

fs/ceph/ioctl.c:187:26: error: variable 'oid' is uninitialized when used within its own initialization [-Werror,-Wuninitialized]
CEPH_DEFINE_OID_ONSTACK(oid);
^~~
include/linux/ceph/osdmap.h:122:52: note: expanded from macro 'CEPH_DEFINE_OID_ONSTACK'
struct ceph_object_id oid = CEPH_OID_INIT_ONSTACK(oid)
~~~ ^~~
include/linux/ceph/osdmap.h:120:29: note: expanded from macro 'CEPH_OID_INIT_ONSTACK'
({ ceph_oid_init(&oid); oid; })
^~~

We use this trick in other places, but it is completely unnecessary
here, as we can just use a regular struct initializer.

Signed-off-by: Arnd Bergmann <[email protected]>
---
v2: rearrange to only have one instance of the initializer
---
include/linux/ceph/osdmap.h | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
index 5675b1f09bc5..8794cf0f0b39 100644
--- a/include/linux/ceph/osdmap.h
+++ b/include/linux/ceph/osdmap.h
@@ -110,17 +110,16 @@ struct ceph_object_id {
int name_len;
};

+#define CEPH_OID_INITIALIZER(oid) { .name = (oid).inline_name }
+
+#define CEPH_DEFINE_OID_ONSTACK(oid) \
+ struct ceph_object_id oid = CEPH_OID_INITIALIZER(oid)
+
static inline void ceph_oid_init(struct ceph_object_id *oid)
{
- oid->name = oid->inline_name;
- oid->name_len = 0;
+ *oid = (struct ceph_object_id)CEPH_OID_INITIALIZER(*oid);
}

-#define CEPH_OID_INIT_ONSTACK(oid) \
- ({ ceph_oid_init(&oid); oid; })
-#define CEPH_DEFINE_OID_ONSTACK(oid) \
- struct ceph_object_id oid = CEPH_OID_INIT_ONSTACK(oid)
-
static inline bool ceph_oid_empty(const struct ceph_object_id *oid)
{
return oid->name == oid->inline_name && !oid->name_len;
--
2.20.0

2019-03-27 16:32:58

by Ilya Dryomov

Subject: Re: [PATCH] [v2] ceph: fix clang warning for CEPH_DEFINE_OID_ONSTACK

On Mon, Mar 25, 2019 at 1:51 PM Arnd Bergmann <[email protected]> wrote:
>
> clang complains about assigning a variable to itself during the
> declaration:
>
> fs/ceph/ioctl.c:187:26: error: variable 'oid' is uninitialized when used within its own initialization [-Werror,-Wuninitialized]
> CEPH_DEFINE_OID_ONSTACK(oid);
> ^~~
> include/linux/ceph/osdmap.h:122:52: note: expanded from macro 'CEPH_DEFINE_OID_ONSTACK'
> struct ceph_object_id oid = CEPH_OID_INIT_ONSTACK(oid)
> ~~~ ^~~
> include/linux/ceph/osdmap.h:120:29: note: expanded from macro 'CEPH_OID_INIT_ONSTACK'
> ({ ceph_oid_init(&oid); oid; })
> ^~~
>
> We use this trick in other places, but it is completely unnecessary
> here, as we can just use a regular struct initializer.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> v2: rearrange to only have one instance of the initializer
> ---
> include/linux/ceph/osdmap.h | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
> index 5675b1f09bc5..8794cf0f0b39 100644
> --- a/include/linux/ceph/osdmap.h
> +++ b/include/linux/ceph/osdmap.h
> @@ -110,17 +110,16 @@ struct ceph_object_id {
> int name_len;
> };
>
> +#define CEPH_OID_INITIALIZER(oid) { .name = (oid).inline_name }
> +
> +#define CEPH_DEFINE_OID_ONSTACK(oid) \
> + struct ceph_object_id oid = CEPH_OID_INITIALIZER(oid)
> +
> static inline void ceph_oid_init(struct ceph_object_id *oid)
> {
> - oid->name = oid->inline_name;
> - oid->name_len = 0;
> + *oid = (struct ceph_object_id)CEPH_OID_INITIALIZER(*oid);
> }
>
> -#define CEPH_OID_INIT_ONSTACK(oid) \
> - ({ ceph_oid_init(&oid); oid; })
> -#define CEPH_DEFINE_OID_ONSTACK(oid) \
> - struct ceph_object_id oid = CEPH_OID_INIT_ONSTACK(oid)
> -
> static inline bool ceph_oid_empty(const struct ceph_object_id *oid)
> {
> return oid->name == oid->inline_name && !oid->name_len;

Applied.

Thanks,

Ilya