From: Olivier Matz <olivier.matz@6wind.com> To: Luc Pelletier <lucp.at.work@gmail.com> Cc: jianfeng.tan@intel.com, Honnappa.Nagarahalli@arm.com, dev@dpdk.org, stable@dpdk.org Subject: Re: [dpdk-dev] [PATCH v6] eal: fix race in ctrl thread creation Date: Wed, 7 Apr 2021 16:57:22 +0200 Message-ID: <20210407145722.GN1650@platinum> (raw) In-Reply-To: <20210407144236.128365-1-lucp.at.work@gmail.com> Hi Luc, On Wed, Apr 07, 2021 at 10:42:37AM -0400, Luc Pelletier wrote: > The creation of control threads uses a pthread barrier for > synchronization. This patch fixes a race condition where the pthread > barrier could get destroyed while one of the threads has not yet > returned from the pthread_barrier_wait function, which could result in > undefined behaviour. > > Fixes: 3a0d465d4c53 ("eal: fix use-after-free on control thread creation") > Cc: jianfeng.tan@intel.com > Cc: stable@dpdk.org > > Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com> > --- > > Hi Olivier, > > I've made the changes as you requested. However, I'm using the atomic > built-ins for reading and writing start_routine; I think they're > required to prevent any re-reordering. > > Please let me know what you think. From [1], it seems that pthread_barrier_wait() is a full memory barrier. So while not wrong, I think using atomic built-ins it is not needed. [1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_11 > > lib/librte_eal/common/eal_common_thread.c | 63 +++++++++++++---------- > 1 file changed, 35 insertions(+), 28 deletions(-) > > diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c > index 73a055902..fcb386f77 100644 > --- a/lib/librte_eal/common/eal_common_thread.c > +++ b/lib/librte_eal/common/eal_common_thread.c > @@ -170,25 +170,34 @@ struct rte_thread_ctrl_params { > void *(*start_routine)(void *); > void *arg; > pthread_barrier_t configured; > + unsigned int refcnt; > }; > > +static void ctrl_params_free(struct rte_thread_ctrl_params *params) > +{ > + if (__atomic_sub_fetch(¶ms->refcnt, 1, __ATOMIC_ACQ_REL) == 0) { > + pthread_barrier_destroy(¶ms->configured); > + free(params); > + } > +} > + > 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; > struct rte_thread_ctrl_params *params = arg; > - void *(*start_routine)(void *) = params->start_routine; > + void *(*start_routine)(void *); > void *routine_arg = params->arg; > > __rte_thread_init(rte_lcore_id(), cpuset); > > - ret = pthread_barrier_wait(¶ms->configured); > - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { > - pthread_barrier_destroy(¶ms->configured); > - free(params); > - } > + pthread_barrier_wait(¶ms->configured); > + start_routine = __atomic_load_n(¶ms->start_routine, __ATOMIC_ACQUIRE); > + ctrl_params_free(params); > + > + if (start_routine == NULL) > + return NULL; > > return start_routine(routine_arg); > } > @@ -210,14 +219,15 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name, > > params->start_routine = start_routine; > params->arg = arg; > + params->refcnt = 2; > > - pthread_barrier_init(¶ms->configured, NULL, 2); > + ret = pthread_barrier_init(¶ms->configured, NULL, 2); > + if (ret != 0) > + goto fail_no_barrier; > > ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params); > - if (ret != 0) { > - free(params); > - return -ret; > - } > + if (ret != 0) > + goto fail_with_barrier; > > if (name != NULL) { > ret = rte_thread_setname(*thread, name); > @@ -227,25 +237,22 @@ 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) > + __atomic_store_n(¶ms->start_routine, NULL, __ATOMIC_RELEASE); > + pthread_barrier_wait(¶ms->configured); > + ctrl_params_free(params); > > - ret = pthread_barrier_wait(¶ms->configured); > - if (ret == PTHREAD_BARRIER_SERIAL_THREAD) { > - pthread_barrier_destroy(¶ms->configured); > - free(params); > - } > + if (ret != 0) > + pthread_join(*thread, NULL); > > - return 0; > + return -ret; > + > +fail_with_barrier: > + pthread_barrier_destroy(¶ms->configured); > + > +fail_no_barrier: > + free(params); > > -fail: > - if (PTHREAD_BARRIER_SERIAL_THREAD == > - pthread_barrier_wait(¶ms->configured)) { > - pthread_barrier_destroy(¶ms->configured); > - free(params); > - } > - pthread_cancel(*thread); > - pthread_join(*thread, NULL); > return -ret; > } > > -- > 2.25.1 >
next prev parent reply other threads:[~2021-04-07 14:57 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 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 [this message] 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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