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From: Andrew Rybchenko <arybchenko@solarflare.com>
To: Jerin Jacob <jerinjacobk@gmail.com>,
	Tonghao Zhang <xiangxia.m.yue@gmail.com>
Cc: dpdk-dev <dev@dpdk.org>, Olivier Matz <olivier.matz@6wind.com>,
	Gage Eads <gage.eads@intel.com>,
	"Artem V. Andreev" <artem.andreev@oktetlabs.ru>,
	Jerin Jacob <jerinj@marvell.com>,
	Nithin Dabilpuram <ndabilpuram@marvell.com>,
	Vamsi Attunuru <vattunuru@marvell.com>,
	"Hemant Agrawal" <hemant.agrawal@nxp.com>
Subject: Re: [dpdk-dev] [PATCH dpdk-dev v3] mempool: sort the rte_mempool_ops by name
Date: Sat, 7 Mar 2020 15:51:29 +0300	[thread overview]
Message-ID: <7420c590-4906-34e2-b0b8-d412df9005c8@solarflare.com> (raw)
In-Reply-To: <CALBAE1MUEgG_fZXyvHA70PZSp0uoez8tT7dXkasqe=G0qQSZ0g@mail.gmail.com>

On 3/6/20 4:37 PM, Jerin Jacob wrote:
> On Fri, Mar 6, 2020 at 7:06 PM <xiangxia.m.yue@gmail.com> wrote:
>> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>>
>> The order of mempool initiation affects mempool index in the
>> rte_mempool_ops_table. For example, when building APPs with:
>>
>> $ gcc -lrte_mempool_bucket -lrte_mempool_ring ...
>>
>> The "bucket" mempool will be registered firstly, and its index
>> in table is 0 while the index of "ring" mempool is 1. DPDK
>> uses the mk/rte.app.mk to build APPs, and others, for example,
>> Open vSwitch, use the libdpdk.a or libdpdk.so to build it.
>> The mempool lib linked in dpdk and Open vSwitch is different.
>>
>> The mempool can be used between primary and secondary process,
>> such as dpdk-pdump and pdump-pmd/Open vSwitch(pdump enabled).
>> There will be a crash because dpdk-pdump creates the "ring_mp_mc"
>> ring which index in table is 0, but the index of "bucket" ring
>> is 0 in Open vSwitch. If Open vSwitch use the index 0 to get
>> mempool ops and malloc memory from mempool. The crash will occur:
>>
>>      bucket_dequeue (access null and crash)
>>      rte_mempool_get_ops (should get "ring_mp_mc",
>>                           but get "bucket" mempool)
>>      rte_mempool_ops_dequeue_bulk
>>      ...
>>      rte_pktmbuf_alloc
>>      rte_pktmbuf_copy
>>      pdump_copy
>>      pdump_rx
>>      rte_eth_rx_burst
>>
>> To avoid the crash, there are some solution:
>> * constructor priority: Different mempool uses different
>>    priority in RTE_INIT, but it's not easy to maintain.
>>
>> * change mk/rte.app.mk: Change the order in mk/rte.app.mk to
>>    be same as libdpdk.a/libdpdk.so, but when adding a new mempool
>>    driver in future, we must make sure the order.
>>
>> * register mempool orderly: Sort the mempool when registering,
>>    so the lib linked will not affect the index in mempool table.
>>
>> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>> Acked-by: Olivier Matz <olivier.matz@6wind.com>
> Acked-by: Jerin Jacob <jerinj@marvell.com>

The patch is OK, but the fact that ops index changes during
mempool driver lifetime is frightening. In fact it breaks
rte_mempool_register_ops() return value semantics (read
as API break). The return value is not used in DPDK, but it
is a public function. If I'm not mistaken it should be taken
into account.

Also I remember patches which warn about above behaviour
in documentation. If behaviour changes, corresponding
documentation must be updated.



  reply	other threads:[~2020-03-07 12:52 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-02  1:57 [dpdk-dev] [PATCH] " xiangxia.m.yue
2020-03-02 13:45 ` Jerin Jacob
2020-03-04 13:17   ` Tonghao Zhang
2020-03-04 13:33     ` Jerin Jacob
2020-03-04 14:46       ` Tonghao Zhang
2020-03-04 15:14         ` Jerin Jacob
2020-03-04 15:25           ` Tonghao Zhang
2020-03-05  8:20 ` [dpdk-dev] [PATCH dpdk-dev v2] " xiangxia.m.yue
2020-03-05 16:57   ` Olivier Matz
2020-03-06 13:36 ` [dpdk-dev] [PATCH dpdk-dev v3] " xiangxia.m.yue
2020-03-06 13:37   ` Jerin Jacob
2020-03-07 12:51     ` Andrew Rybchenko [this message]
2020-03-07 12:54       ` Andrew Rybchenko
2020-03-09  3:01         ` Tonghao Zhang
2020-03-09  8:27           ` Olivier Matz
2020-03-09  8:55             ` Tonghao Zhang
2020-03-09  9:05               ` Olivier Matz
2020-03-09 13:15               ` David Marchand
2020-03-16  7:43                 ` Tonghao Zhang
2020-03-16  7:55                   ` Olivier Matz
2020-03-24  9:35             ` Andrew Rybchenko
2020-03-24 12:41               ` Tonghao Zhang
2020-04-09 10:52 ` [dpdk-dev] [PATCH dpdk-dev 1/2] eal: introduce last-init queue for libraries initialization xiangxia.m.yue
2020-04-09 10:53   ` [dpdk-dev] [PATCH dpdk-dev 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-09 11:31   ` [dpdk-dev] [PATCH dpdk-dev 1/2] eal: introduce last-init queue for libraries initialization Jerin Jacob
2020-04-09 15:04     ` Tonghao Zhang
2020-04-09 15:02 ` [dpdk-dev] [PATCH dpdk-dev v2 1/2] eal: introduce rte-init " xiangxia.m.yue
2020-04-09 15:02   ` [dpdk-dev] [PATCH dpdk-dev v2 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-10  6:18   ` [dpdk-dev] [PATCH dpdk-dev v2 1/2] eal: introduce rte-init queue for libraries initialization Jerin Jacob
2020-04-10 13:11     ` Jerin Jacob
2020-04-12  3:20       ` Tonghao Zhang
2020-04-12  3:32         ` Tonghao Zhang
2020-04-13 11:32           ` Jerin Jacob
2020-04-13 14:21 ` [dpdk-dev] [PATCH dpdk-dev v3 " xiangxia.m.yue
2020-04-13 14:21   ` [dpdk-dev] [PATCH dpdk-dev v3 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-16 22:27     ` Thomas Monjalon
2020-04-27  8:03       ` Tonghao Zhang
2020-04-27 11:40         ` Thomas Monjalon
2020-04-27 12:51           ` Tonghao Zhang
2020-04-28 13:22             ` Tonghao Zhang
2020-05-04  7:42               ` Olivier Matz
2021-03-25 14:24                 ` David Marchand
2020-04-23 13:38     ` Andrew Rybchenko
2020-04-27  5:23       ` Tonghao Zhang

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