Re: [PATCH] objpool: fix minimum alignment of 'struct objpool_slot'

["wuqiang.matt" <wuqiang.matt@bytedance.com>]

On 2026/2/10 18:35, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Members of objpool_slot get passed into try_cmpxchg_release(),
> which does not work on most architectures unless they are
> naturally aligned. Marking the structure as packed makes it
> only byte-aligned, as shown by this (normally disabled) warning:
> 
> include/linux/objpool.h:156:56: warning: taking address of packed member of 'struct objpool_slot' may result in an unaligned pointer value [-Waddress-of-packed-member]
>    156 |                 if (try_cmpxchg_release(&slot->head, &head, head + 1))
>        |                                                       ~^~~~~~~~~~~~
> 
> As the struct members are all tightly packed on all architectures,
> Just remove the '__packed annotation to give it the required
> alignment of the native word size.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   include/linux/objpool.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/objpool.h b/include/linux/objpool.h
> index b713a1fe7521..f678b35b20b1 100644
> --- a/include/linux/objpool.h
> +++ b/include/linux/objpool.h
> @@ -56,7 +56,7 @@ struct objpool_slot {
>   	uint32_t            last;
>   	uint32_t            mask;
>   	void               *entries[];
> -} __packed;
> +};
>   
>   struct objpool_head;
>   

Reviewed-by: wuqiang.matt <wuqiang.matt@bytedance.com>

Regards,
Matt Wu