Re: [PATCH 2/2] init: Combine blacklist entry allocations in initcall_blacklist()

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 15 Nov 2026 15:23:21 +0100 Thorsten Blum <blum@kernel.org> wrote:

> Use a flexible array member for the function name and allocate it
> together with the blacklist entry. This removes the pointer and saves
> one allocation call per blacklist entry.
> 

Looks OK, thanks.

> --- a/init/main.c
> +++ b/init/main.c
> @@ -1266,7 +1267,7 @@ static void __init do_ctors(void)
>  #ifdef CONFIG_KALLSYMS
>  struct blacklist_entry {
>  	struct list_head next;
> -	char *buf;
> +	char buf[];
>  };

We need some care with the flexible arrays.  If some code does a struct
copy:

	struct blacklist_entry bl1 = bl2;

then the old code would have worked but after this change bl1 has
garbage in its buf[].

afaict none of our static checking tools (gcc, clang, smatch, sparse)
will catch this.