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

From: Ilya Dryomov
Date: Fri Mar 22 2019 - 10:40:28 EST


On Fri, Mar 22, 2019 at 3:08 PM Arnd Bergmann <arnd@xxxxxxxx> 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 <arnd@xxxxxxxx>
> ---
> include/linux/ceph/osdmap.h | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
> index 5675b1f09bc5..82f957a7a0d6 100644
> --- a/include/linux/ceph/osdmap.h
> +++ b/include/linux/ceph/osdmap.h
> @@ -116,10 +116,8 @@ static inline void ceph_oid_init(struct ceph_object_id *oid)
> oid->name_len = 0;
> }
>
> -#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)
> + struct ceph_object_id oid = { .name = oid.inline_name }
>
> static inline bool ceph_oid_empty(const struct ceph_object_id *oid)
> {

Hi Arnd,

I don't like this because the initialization is no longer contained to
ceph_oid_init(). Now there are two things to patch instead of one.

How is this going to be fixed in other places?

Thanks,

Ilya