Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] [v2] bcache: hide variable-sized types from uapi header check | Date | Tue, 28 Sep 2021 10:55:50 +0200 |
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From: Arnd Bergmann <arnd@arndb.de>
The headers_check helper complains about a GNU extension in one of the exported headers:
linux/bcache.h:354:2: warning: field '' with variable sized type 'union jset::(anonymous at ./usr/include/linux/bcache.h:354:2)' not at the end of a struct or class is a GNU extension [-Wgnu-variable-sized-type-not-at-end] BKEY_PADDED(uuid_bucket); ^ linux/bcache.h:134:2: note: expanded from macro 'BKEY_PADDED' union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; } ^
Address this by enclosing the GNU extensions in an #ifdef: Since the header check is done with --std=c90, this shuts up the warning and makes it possible to include the header file C90 user space applications, but allows applications built with --std=gnu89 or higher to use those parts.
Another alternative would be to exclude this header from the check, but the GNU extension check seems more sensible.
Fixes: 81ab4190ac17 ("bcache: Pull on disk data structures out into a separate header") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- v2: use __STRICT_ANSI__ check instead of __KERNEL__.
I think this version is better than the first, let me know if that works for you. --- include/uapi/linux/bcache.h | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h index cf7399f03b71..b7901e986193 100644 --- a/include/uapi/linux/bcache.h +++ b/include/uapi/linux/bcache.h @@ -23,9 +23,13 @@ static inline void SET_##name(type *k, __u64 v) \ struct bkey { __u64 high; __u64 low; +#ifndef __STRICT_ANSI__ + /* gcc extension not meant for user space */ __u64 ptr[]; +#endif }; +#ifndef __STRICT_ANSI__ #define KEY_FIELD(name, field, offset, size) \ BITMASK(name, struct bkey, field, offset, size) @@ -127,6 +131,8 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys) return (struct bkey *) (d + nr_keys); } +#endif + /* Enough for a key with 6 pointers */ #define BKEY_PAD 8 -- 2.29.2
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