Re: [dpdk-stable] [PATCH v2] eal: fix crash when the random init

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2020-04-15 09:43, xiangxia.m.yue@gmail.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>
> When rte_rand_init is invoked, and the kernel running dpdk does't
> support *getentropy, at the same time, the cpu does't support rdseed,
> then rte_rand_init invoked rte_get_timer_cycles which invoked
> rte_get_hpet_cycles while *eal_hpet is not available.

You fail to mention that HPET must be enabled in the DPDK build (which 
it is not, by default), and enabled in the BIOS, for this bug to be 
triggered.


> To fix that, use rte_get_tsc_cycles instread of rte_get_timer_cycles.


"instead"


With those updates,

Acked-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>

> Fixes: faf8fd252785 ("eal: improve entropy for initial PRNG seed")
> Fixes: 3f002f069612 ("eal: replace libc-based random generation with LFSR")
>
> Cc: stable@dpdk.org
>
> Reported-by: Ravi Kerur <rkerur@gmail.com>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> ---
> v2:
> * use rte_get_tsc_cycles instread of rte_get_timer_cycles
>
> ---
>   lib/librte_eal/common/rte_random.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/common/rte_random.c b/lib/librte_eal/common/rte_random.c
> index 57ec8fb2b3dd..b7a089ac4fe0 100644
> --- a/lib/librte_eal/common/rte_random.c
> +++ b/lib/librte_eal/common/rte_random.c
> @@ -198,7 +198,7 @@ struct rte_rand_state *__rte_rand_get_state(void)
>   		return (uint64_t)rdseed_low | ((uint64_t)rdseed_high << 32);
>   #endif
>   	/* second fallback: seed using rdtsc */
> -	return rte_get_timer_cycles();
> +	return rte_get_tsc_cycles();
>   }
>   
>   RTE_INIT(rte_rand_init)