From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: "Carrillo, Erik G" <erik.g.carrillo@intel.com>,
"rsanford@akamai.com" <rsanford@akamai.com>,
"thomas@monjalon.net" <thomas@monjalon.net>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2] timer: fix resource leak in finalize
Date: Wed, 8 May 2019 09:49:58 +0100 [thread overview]
Message-ID: <efc5b7ac-1b13-f219-9bd7-8f8805450e43@intel.com> (raw)
In-Reply-To: <BE54F058557D9A4FAC1D84E2FC6D875723405E77@fmsmsx115.amr.corp.intel.com>
On 07-May-19 11:04 PM, Carrillo, Erik G wrote:
> Hi Anatoly,
>
> Thanks for the review. Comments in-line:
>
> <...snipped...>
>
>>> #define RTE_MAX_DATA_ELS 64
>>> +static const struct rte_memzone *rte_timer_data_mz; static
>>> +rte_atomic16_t *rte_timer_mz_refcnt;
>>> static struct rte_timer_data *rte_timer_data_arr;
>>> static const uint32_t default_data_id;
>>> static uint32_t rte_timer_subsystem_initialized; @@ -155,6 +157,7 @@
>>> rte_timer_subsystem_init_v1905(void)
>>> struct rte_timer_data *data;
>>> int i, lcore_id;
>>> static const char *mz_name = "rte_timer_mz";
>>> + size_t data_arr_size = RTE_MAX_DATA_ELS *
>>> +sizeof(*rte_timer_data_arr);
>>
>> nitpicking, but... const?
>>
>
> No problem - I'll make this change if this line persists into the next version.
>
> <...snipped...>
>
>>>
>>> @@ -205,8 +216,11 @@
>> BIND_DEFAULT_SYMBOL(rte_timer_subsystem_init, _v1905, 19.05);
>>> void __rte_experimental
>>> rte_timer_subsystem_finalize(void)
>>> {
>>> - if (rte_timer_data_arr)
>>> - rte_free(rte_timer_data_arr);
>>> + if (!rte_timer_subsystem_initialized)
>>> + return;
>>> +
>>> + if (rte_atomic16_dec_and_test(rte_timer_mz_refcnt))
>>> + rte_memzone_free(rte_timer_data_mz);
>>
>> I think there's a race here. You may get preempted after test but before
>> free, where another secondary could initialize. As far as i know, we also
>
> Indeed, thanks for catching this.
>
>> support a case when secondary initializes after primary stops running.
>>
>> Let's even suppose that we allow secondary processes to initialize the timer
>> subsystem by reserving memzone and checking rte_errno. You would still
>> have a chance of two init/deinit conflicting, because there's a hole between
>> memzone allocation and atomic increment.
>>
>> I don't think this race can be resolved in a safe way, so we might just have to
>> settle for a memory leak.
>>
>
> I don't see a solution here currently either. I'll look at removing the memzone_free()
> call and possibly the rte_timer_subsystem_finalize() API, since it seems like
> there's no reason for it to exist if it can't free the allocations.
I wonder if there are other places in DPDK where this pattern is used.
Technically, this kind of thing /could/ be resolved by having something
in our multiprocess shared memory outside of DPDK heap. I.e. store
something in rte_eal_memconfig like some other things do. This change,
however, would require an ABI break, so while changing this particular
API won't need a deprecation notice, the change itself would.
>
> Regards,
> Erik
>
>>>
>>> rte_timer_subsystem_initialized = 0;
>>> }
>>>
>>
>>
>> --
>> Thanks,
>> Anatoly
--
Thanks,
Anatoly
next prev parent reply other threads:[~2019-05-08 8:50 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 19:00 [dpdk-dev] [PATCH] " Erik Gabriel Carrillo
2019-05-01 19:00 ` Erik Gabriel Carrillo
2019-05-02 9:18 ` Burakov, Anatoly
2019-05-02 9:18 ` Burakov, Anatoly
2019-05-02 12:19 ` Carrillo, Erik G
2019-05-02 12:19 ` Carrillo, Erik G
2019-05-02 13:03 ` Burakov, Anatoly
2019-05-02 13:03 ` Burakov, Anatoly
2019-05-02 13:48 ` Carrillo, Erik G
2019-05-02 13:48 ` Carrillo, Erik G
2019-05-03 22:54 ` [dpdk-dev] [PATCH v2] " Erik Gabriel Carrillo
2019-05-03 22:54 ` Erik Gabriel Carrillo
2019-05-07 11:03 ` Burakov, Anatoly
2019-05-07 11:03 ` Burakov, Anatoly
2019-05-07 22:04 ` Carrillo, Erik G
2019-05-07 22:04 ` Carrillo, Erik G
2019-05-08 8:49 ` Burakov, Anatoly [this message]
2019-05-08 8:49 ` Burakov, Anatoly
2019-05-08 23:01 ` Carrillo, Erik G
2019-05-08 23:01 ` Carrillo, Erik G
2019-05-09 7:44 ` Thomas Monjalon
2019-05-09 7:44 ` Thomas Monjalon
2019-05-08 22:35 ` [dpdk-dev] [PATCH v3] " Erik Gabriel Carrillo
2019-05-08 22:35 ` Erik Gabriel Carrillo
2019-05-09 8:29 ` Burakov, Anatoly
2019-05-09 8:29 ` Burakov, Anatoly
2019-06-05 9:33 ` Thomas Monjalon
2019-06-05 9:47 ` Burakov, Anatoly
2019-06-25 16:11 ` [dpdk-dev] [PATCH 0/2] Fix timer resource leak Anatoly Burakov
2019-07-05 13:20 ` [dpdk-dev] [PATCH v2 0/1] " Anatoly Burakov
2019-07-05 17:22 ` [dpdk-dev] [PATCH v3 " Anatoly Burakov
2019-07-05 17:22 ` [dpdk-dev] [PATCH v3 1/1] timer: fix resource leak in finalize Anatoly Burakov
2019-07-05 22:06 ` Thomas Monjalon
2019-07-05 13:20 ` [dpdk-dev] [PATCH v2 " Anatoly Burakov
2019-06-25 16:11 ` [dpdk-dev] [PATCH 1/2] eal: add internal locks for timer lib into EAL Anatoly Burakov
2019-06-27 18:41 ` Carrillo, Erik G
2019-07-04 9:09 ` David Marchand
2019-07-04 10:44 ` Burakov, Anatoly
2019-06-25 16:11 ` [dpdk-dev] [PATCH 2/2] timer: fix resource leak in finalize Anatoly Burakov
2019-06-27 18:48 ` Carrillo, Erik G
2019-07-04 9:10 ` David Marchand
2019-07-04 10:45 ` Burakov, Anatoly
2019-07-04 10:50 ` David Marchand
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