Re: [PATCH v4 04/11] mips: use fallback for random_get_entropy() instead of zero

[Thomas Bogendoerfer <tsbogend@alpha.franken.de>]

On Wed, Apr 13, 2022 at 01:54:04PM +0200, Jason A. Donenfeld wrote:
> In the event that random_get_entropy() can't access a cycle counter or
> similar, falling back to returning 0 is really not the best we can do.
> Instead, at least calling random_get_entropy_fallback() would be
> preferable, because that always needs to return _something_, even
> falling back to jiffies eventually. It's not as though
> random_get_entropy_fallback() is super high precision or guaranteed to
> be entropic, but basically anything that's not zero all the time is
> better than returning zero all the time.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  arch/mips/include/asm/timex.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/include/asm/timex.h b/arch/mips/include/asm/timex.h
> index b05bb70a2e46..abc60a6395e3 100644
> --- a/arch/mips/include/asm/timex.h
> +++ b/arch/mips/include/asm/timex.h
> @@ -94,7 +94,7 @@ static inline unsigned long random_get_entropy(void)
>  	else if (likely(imp != PRID_IMP_R6000 && imp != PRID_IMP_R6000A))
>  		return read_c0_random();
>  	else
> -		return 0;	/* no usable register */
> +		return random_get_entropy_fallback();	/* no usable register */
>  }
>  #define random_get_entropy random_get_entropy
>  
> -- 
> 2.35.1

Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

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