linux-kernel - Re: [PATCH] init: call time_init() before rand

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Date:   Sat, 14 May 2022 06:18:19 +0900
From:   Stafford Horne <shorne@...il.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] init: call time_init() before rand_initialize()

On Thu, May 05, 2022 at 02:31:14AM +0200, Jason A. Donenfeld wrote:
> Currently time_init() is called before rand_initialize(), but
> rand_initialize() makes use of the timer on various platforms, and
> sometimes this timer needs to be initialized by time_init() first. In
> order to not return zero, reverse the order of these two calls. The
> block doing random initialization was right before time_init() before,
> so changing the order shouldn't have any complicated effects.
> 
> Cc: Stafford Horne <shorne@...il.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>

I was thinking along the same lines when I looked into the OpenRISC issue
that we fixed discussed here:

 - https://lore.kernel.org/all/Ym27sFdFZEt5QV0i@antec/

Though, I was not sure as to any dependency issues caused by changing the
order.  Having it in -next and testing for a while should be able to
bring out any bug.

As for this patch:

Reviewed-by: Stafford Horne <shorne@...il.com>

> ---
> Andrew - this file has no formal maintainer, but you've signed the most
> commits, so I'm CC'ing you. This has some interactions with my
> random.git tree, so unless there are objections, I'll queue it up there.
> -Jason
> 
>  init/main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/init/main.c b/init/main.c
> index 98182c3c2c4b..e37ec99cf56d 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1035,6 +1035,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
>  	softirq_init();
>  	timekeeping_init();
>  	kfence_init();
> +	time_init();
>  
>  	/*
>  	 * For best initial stack canary entropy, prepare it after:
> @@ -1049,7 +1050,6 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
>  	add_device_randomness(command_line, strlen(command_line));
>  	boot_init_stack_canary();
>  
> -	time_init();
>  	perf_event_init();
>  	profile_init();
>  	call_function_init();
> -- 
> 2.35.1
>