From: David Marchand <david.marchand@redhat.com>
To: "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>
Cc: Tonghao Zhang <xiangxia.m.yue@gmail.com>,
Stephen Hemminger <stephen@networkplumber.org>,
dpdk-dev <dev@dpdk.org>, "stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH dpdk-dev] rte_random: fix crash when random init
Date: Tue, 14 Apr 2020 15:35:37 +0200 [thread overview]
Message-ID: <CAJFAV8zkPyMbmwwGwOkNkdHcwp546VfRirSQC16SMhRp09-A+g@mail.gmail.com> (raw)
In-Reply-To: <e98b60ee-20be-ac9e-2eaa-e1b3a670adf1@ericsson.com>
On Tue, Apr 14, 2020 at 3:20 PM Mattias Rönnblom
<mattias.ronnblom@ericsson.com> wrote:
>
> On 2020-04-14 06:43, Tonghao Zhang wrote:
> > On Tue, Apr 14, 2020 at 12:07 PM Stephen Hemminger
> > <stephen@networkplumber.org> wrote:
> >> On Sun, 12 Apr 2020 16:27:53 +0800
> >> xiangxia.m.yue@gmail.com wrote:
> >>
> >>> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> >>>
> >>> When rte_rand_init is invoked, and the kernel
> >>> (kernel version < 3.17) running dpdk does't support
> >>> *getentropy, at the same time, the cpu does't support
> >>> rdseed, the rte_rand_init will invoke rte_get_timer_cycles
> >>> which function will invoke rte_get_hpet_cycles
> >>> (RTE_LIBEAL_USE_HPET was enabled) while *eal_hpet is not
> >>> allocated.
> >>>
> >>> Fixes: faf8fd252785 ("eal: improve entropy for initial PRNG seed")
> >>> Fixes: 3f002f069612 ("eal: replace libc-based random generation with LFSR")
> >>>
> >>> Cc: stable@dpdk.org
> >>>
> >>> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> >> Are you sure this patch won't change current default to use HPET (which is slower)?
> > In rte_eal_timer_init (linux/eal_timer.c)， it will set
> > eal_timer_source = EAL_TIMER_TSC too.
> > So after rte_eal_init, eal_timer_source == EAL_TIMER_TSC which is the
> > default timer source actually.
> > Then this patch will affect RTE_INIT function which invoke
> > rte_get_timer_cycles. but hpet is not available yet.
>
>
> Would using rte_rdtsc() directly be an option?
s/rte_rdtsc/rte_get_tsc_cycles/
This could work, but I am a bit surprised to see an initialisation in
a constructor.
The commitlog that moved rte_srand() from rte_eal_init does not
explain why it was moved.
--
David Marchand
next prev parent reply other threads:[~2020-04-14 13:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-12 8:27 xiangxia.m.yue
2020-04-14 4:06 ` Stephen Hemminger
2020-04-14 4:43 ` Tonghao Zhang
2020-04-14 13:19 ` Mattias Rönnblom
2020-04-14 13:35 ` David Marchand [this message]
2020-04-14 15:37 ` Mattias Rönnblom
2020-04-14 23:42 ` Tonghao Zhang
2020-04-15 6:01 ` Mattias Rönnblom
2020-04-15 8:10 ` David Marchand
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