linux-kernel - Re: [PATCH 44/74] lto: Mark functions used by the vsyscall init code visible

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Date:	Sat, 01 Sep 2012 17:26:22 +0200
From:	Michal Marek <mmarek@...e.cz>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-kbuild@...r.kernel.org, JBeulich@...e.com,
	akpm@...ux-foundation.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 44/74] lto: Mark functions used by the vsyscall init code
 visible

Dne 19.8.2012 04:56, Andi Kleen napsal(a):
> From: Andi Kleen <ak@...ux.intel.com>
> 
> The vsyscall code is compiled without LTO. This also includes
> its init function. The function which are called by it have
> to be visible, otherwise they could be optimized away
> 
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  drivers/char/random.c |    2 +-
>  include/linux/mm.h    |    1 +
>  mm/vmalloc.c          |    2 +-
>  3 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index b86eae9..33c8fe5 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1450,7 +1450,7 @@ late_initcall(random_int_secret_init);
>   * depleting entropy is too high
>   */
>  static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
> -unsigned int get_random_int(void)
> +__visible unsigned int get_random_int(void)

I think that there should be a comment why the symbol needs to be
visible (just copy the reasoning from the changelog). Otherwise someone
might attempt to do a cleanup a few years later, noticing that there is
no assembler code calling get_random_int().

Michal
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