From: Luc Pelletier <lucp.at.work@gmail.com>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: dev@dpdk.org, jianfeng.tan@intel.com, david.marchand@redhat.com,
stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] eal: fix race in ctrl thread creation
Date: Thu, 25 Mar 2021 10:42:38 -0400 [thread overview]
Message-ID: <CAFeRdtA_5MXnCgxtXZUy6tBm3ZVQKu47Nu+6fWytSuM=9q_3Lg@mail.gmail.com> (raw)
In-Reply-To: <20210325112731.16324-1-olivier.matz@6wind.com>
Hi Olivier,
> Thank you for reporting this problem and submitting the patch.
> I think the issue can be fixed without any loop, like in this
> patch. What do you think?
I think getting rid of the loop is an excellent idea. Good thinking.
Your version is much cleaner.
> + __atomic_store_n(¶ms->barrier_refcnt, 2, __ATOMIC_RELEASE);
I don't mean to nitpick but I don't think you need to use
__atomic_store_n to initialize the refcnt. Either way is fine of
course :)
Thanks.
Le jeu. 25 mars 2021 à 07:27, Olivier Matz <olivier.matz@6wind.com> a écrit :
>
> As reported by Luc, there is a race where the barrier is destroyed by
> one thread, while the other thread did not yet leave
> pthread_barrier_wait.
>
> This patch fixes the race condition by adding an atomic counter to
> ensure that the barrier is destroyed only it is not used by any thread.
>
> Fixes: 3a0d465d4c53 ("eal: fix use-after-free on control thread creation")
> Cc: jianfeng.tan@intel.com
> Cc: stable@dpdk.org
>
> Reported-by: Luc Pelletier <lucp.at.work@gmail.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>
> Hi Luc,
>
> Thank you for reporting this problem and submitting the patch.
> I think the issue can be fixed without any loop, like in this
> patch. What do you think?
>
> Regards,
> Olivier
>
>
> lib/librte_eal/common/eal_common_thread.c | 38 +++++++++++++----------
> 1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
> index 73a055902a..891f825e87 100644
> --- a/lib/librte_eal/common/eal_common_thread.c
> +++ b/lib/librte_eal/common/eal_common_thread.c
> @@ -170,11 +170,11 @@ struct rte_thread_ctrl_params {
> void *(*start_routine)(void *);
> void *arg;
> pthread_barrier_t configured;
> + unsigned int barrier_refcnt;
> };
>
> static void *ctrl_thread_init(void *arg)
> {
> - int ret;
> struct internal_config *internal_conf =
> eal_get_internal_configuration();
> rte_cpuset_t *cpuset = &internal_conf->ctrl_cpuset;
> @@ -184,8 +184,9 @@ static void *ctrl_thread_init(void *arg)
>
> __rte_thread_init(rte_lcore_id(), cpuset);
>
> - ret = pthread_barrier_wait(¶ms->configured);
> - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
> + pthread_barrier_wait(¶ms->configured);
> + if (__atomic_sub_fetch(¶ms->barrier_refcnt, 1,
> + __ATOMIC_ACQ_REL) == 0) {
> pthread_barrier_destroy(¶ms->configured);
> free(params);
> }
> @@ -210,15 +211,17 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
>
> params->start_routine = start_routine;
> params->arg = arg;
> -
> - pthread_barrier_init(¶ms->configured, NULL, 2);
> -
> - ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
> + __atomic_store_n(¶ms->barrier_refcnt, 2, __ATOMIC_RELEASE);
> + ret = pthread_barrier_init(¶ms->configured, NULL, 2);
> if (ret != 0) {
> free(params);
> return -ret;
> }
>
> + ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
> + if (ret != 0)
> + goto fail;
> +
> if (name != NULL) {
> ret = rte_thread_setname(*thread, name);
> if (ret < 0)
> @@ -227,25 +230,26 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
> }
>
> ret = pthread_setaffinity_np(*thread, sizeof(*cpuset), cpuset);
> - if (ret)
> - goto fail;
> + if (ret != 0)
> + goto fail_cancel;
>
> - ret = pthread_barrier_wait(¶ms->configured);
> - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) {
> + pthread_barrier_wait(¶ms->configured);
> + if (__atomic_sub_fetch(¶ms->barrier_refcnt, 1,
> + __ATOMIC_ACQ_REL) == 0) {
> pthread_barrier_destroy(¶ms->configured);
> free(params);
> }
>
> return 0;
>
> -fail:
> - if (PTHREAD_BARRIER_SERIAL_THREAD ==
> - pthread_barrier_wait(¶ms->configured)) {
> - pthread_barrier_destroy(¶ms->configured);
> - free(params);
> - }
> +fail_cancel:
> pthread_cancel(*thread);
> pthread_join(*thread, NULL);
> +
> +fail:
> + pthread_barrier_destroy(¶ms->configured);
> + free(params);
> +
> return -ret;
> }
>
> --
> 2.29.2
>
next prev parent reply other threads:[~2021-03-25 14:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-24 13:04 [dpdk-dev] [PATCH] eal: fix possible UB on creation of ctrl thread Luc Pelletier
2021-03-25 11:27 ` [dpdk-dev] [PATCH v2] eal: fix race in ctrl thread creation Olivier Matz
2021-03-25 14:42 ` Luc Pelletier [this message]
2021-04-02 4:34 ` Honnappa Nagarahalli
2021-04-06 15:57 ` [dpdk-dev] [PATCH v3] eal: fix possible UB on creation of ctrl thread Luc Pelletier
2021-04-06 16:15 ` [dpdk-dev] [PATCH v3] eal: fix race in ctrl thread creation Luc Pelletier
2021-04-06 21:10 ` Honnappa Nagarahalli
2021-04-07 12:35 ` [dpdk-dev] [PATCH v4] " Luc Pelletier
2021-04-07 12:53 ` [dpdk-dev] [PATCH v5] " Luc Pelletier
2021-04-07 13:22 ` Luc Pelletier
2021-04-07 13:31 ` Olivier Matz
2021-04-07 14:42 ` [dpdk-dev] [PATCH v6] " Luc Pelletier
2021-04-07 14:57 ` Olivier Matz
2021-04-07 15:29 ` [dpdk-dev] [PATCH v7] " Luc Pelletier
2021-04-07 17:15 ` Honnappa Nagarahalli
2021-04-07 15:15 ` [dpdk-dev] [PATCH v5] " Honnappa Nagarahalli
2021-04-07 20:16 ` [dpdk-dev] [PATCH 1/2] " Luc Pelletier
2021-04-08 14:17 ` Olivier Matz
2021-04-08 17:06 ` Honnappa Nagarahalli
2021-04-07 20:16 ` [dpdk-dev] [PATCH 2/2] eal: fix hang in ctrl thread creation error logic Luc Pelletier
2021-04-08 14:20 ` Olivier Matz
2021-04-08 18:01 ` Luc Pelletier
2021-04-09 8:13 ` David Marchand
2021-04-08 17:07 ` Honnappa Nagarahalli
2021-04-09 14:34 ` [dpdk-dev] [dpdk-stable] " David Marchand
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