Re: [dpdk-dev] [RFC V2] ethdev: fix issue that dev close in PMD calls twice

[Huisong Li <lihuisong@huawei.com>]

在 2021/8/24 22:42, Ferruh Yigit 写道:
> On 8/19/2021 4:45 AM, Huisong Li wrote:
>> 在 2021/8/18 19:24, Ferruh Yigit 写道:
>>> On 8/13/2021 9:16 AM, Huisong Li wrote:
>>>> 在 2021/8/13 14:12, Thomas Monjalon 写道:
>>>>> 13/08/2021 04:11, Huisong Li:
>>>>>> Hi, all
>>>>>>
>>>>>> This patch can enhance the security of device uninstallation to
>>>>>> eliminate dependency on user usage methods.
>>>>>>
>>>>>> Can you check this patch?
>>>>>>
>>>>>>
>>>>>> 在 2021/8/3 10:30, Huisong Li 写道:
>>>>>>> Ethernet devices in DPDK can be released by rte_eth_dev_close() and
>>>>>>> rte_dev_remove(). These APIs both call xxx_dev_close() in PMD layer
>>>>>>> to uninstall hardware. However, the two APIs do not have explicit
>>>>>>> invocation restrictions. In other words, at the ethdev layer, it is
>>>>>>> possible to call rte_eth_dev_close() before calling rte_dev_remove()
>>>>>>> or rte_eal_hotplug_remove(). In such a bad scenario,
>>>>> It is not a bad scenario.
>>>>> If there is no more port for the device after calling close,
>>>>> the device should be removed automatically.
>>>>> Keep in mind "close" is for one port, "remove" is for the entire device
>>>>> which can have more than one port.
>>>> I know.
>>>>
>>>> dev_close() is for removing an eth device. And rte_dev_remove() can be used
>>>>
>>>> for removing the rte device and all its eth devices belonging to the rte device.
>>>>
>>>> In rte_dev_remove(), "remove" is executed in primary or one of secondary,
>>>>
>>>> all eth devices having same pci address will be closed and removed.
>>>>
>>>>>>> the primary
>>>>>>> process may be fine, but it may cause that xxx_dev_close() in the PMD
>>>>>>> layer will be called twice in the secondary process. So this patch
>>>>>>> fixes it.
>>>>> If a port is closed in primary, it should be the same in secondary.
>>>>>
>>>>>
>>>>>>> +    /*
>>>>>>> +     * The eth_dev->data->name doesn't be cleared by the secondary process,
>>>>>>> +     * so above "eth_dev" isn't NULL after rte_eth_dev_close() called.
>>>>> This assumption is not clear. All should be closed together.
>>>> However, dev_close() does not have the feature similar to rte_dev_remove().
>>>>
>>>> Namely, it is not guaranteed that all eth devices are closed together in ethdev
>>>> layer. It depends on app or user.
>>>>
>>>> If the app does not close together, the operation of repeatedly uninstalling an
>>>> eth device in the secondary process
>>>>
>>>> will be triggered when dev_close() is first called by one secondary process, and
>>>> then rte_dev_remove() is called.
>>>>
>>>> So I think it should be avoided.
>>> First of all, I am not sure about calling 'rte_eth_dev_close()' or
>>> 'rte_dev_remove()' from the secondary process.
>>> There are explicit checks in various locations to prevent clearing resources
>>> completely from secondary process.
>> There's no denying that.
>>
>> Generally, hardware resources of eth device and shared data of the primary and
>> secondary process
>>
>> are cleared by primary, which are controled by ethdev layer or PMD layer.
>>
>> But there may be some private data or resources of each process (primary or
>> secondary ), such as mp action
>>
>> registered by rte_mp_action_register() or others.  For these resources, the
>> secondary process still needs to clear.
>>
>> Namely, both primary and secondary processes need to prevent repeated offloading
>> of resources.
>>
>>> Calling 'rte_eth_dev_close()' or 'rte_dev_remove()' by secondary is technically
>>> can be done but application needs to be extra cautious and should take extra
>>> measures and synchronization to make it work.
>>> Regular use-case is secondary processes do the packet processing and all control
>>> commands run by primary.
>> You are right. We have a consensus that 'rte_eth_dev_close()' or 'rte_dev_remove()'
>>
>> can be called by primary and secondary processes.
>>
>> But DPDK framework cannot assume user behavior.😁
>>
>> We need to make it more secure and reliable for both primary and secondary
>> processes.
>>
>>> In primary, if you call 'rte_eth_dev_close()' it will clear all ethdev resources
>>> and further 'rte_dev_remove()' call will detect missing ethdev resources and
>>> won't try to clear them again.
>>>
>>> In secondary, if you call 'rte_eth_dev_close()', it WON'T clear all resources
>>> and further 'rte_dev_remove()' call (either from primary or secondary) will try
>>> to clean ethdev resources again. You are trying to prevent this retry in remove
>>> happening for secondary process.
>> Right. However, if secondary process in PMD layer has its own private resources
>> to be
>>
>> cleared, it still need to do it by calling 'rte_eth_dev_close()' or
>> 'rte_dev_remove()'.
>>
>>> In secondary it won't free ethdev resources anyway if you let it continue, but I
>>> guess here you are trying to prevent the PMD dev_close() called again. Why? Is
>>> it just for optimization or does it cause unexpected behavior in the PMD?
>>>
>>>
>>> Overall, to free resources you need to do the 'rte_eth_dev_close()' or
>>> 'rte_dev_remove()' in the primary anyway. So instead of this workaround, I would
>>> suggest making PMD dev_close() safe to be called multiple times (if this is the
>>> problem.)
>> In conclusion,  primary and secondary processes in PMD layer may have their own
>>
>> private data and resources, which need to be processed and released.
>>
>> Currently,  these for PMD are either handled and cleaned up in dev_close() or
>> remove().
>>
>> However, code streams in rte_dev_remove() cannot ensure that the uninstallation
>>
>> from secondary process will not be repeated if rte_eth_dev_close() is first
>> called by
>>
>> secondary(primary is ok, plese review this patch).
>>
>> I think, this is the same for each PMD and is better suited to doing it in
>> ethdev layer.
>>
> This patch prevents to call dev_close() twice in the secondary process, is this
> fixing a theoretical problem or an actual problem?
>
> If it is an actual problem can you please provide details, callstack of the
> problematic case?

We analyzed the code when modifying the bug and found that the problem 
did exist.

The ethdev layer did not guarantee the security.

The general function of the two interfaces is as follows:

rte_eth_dev_close() --> release eth device

rte_dev_remove() -->   release eth device + remove and free 
rte_pci_device(primary andsecondary).

According to the OVS application scenario, first call dev_close() and 
then call

remove(), which is possible.

We constructed this scenario using testpmd to start the secondary 
process(the multi-process

patch of testpmd is being uploaded.). It is proved that the ethdev layer 
cannot guarantee

this security. The callstack is as follows:

**************************************************************************************************************************************************

gdb) set args -a 0000:7d:00.0 -l 2-3 --file-prefix=rte_lee 
--proc-type=auto -- -i --rxq 4 --txq 4 --num-procs=2 --proc-id=1
(gdb) b hns3_dev_uninit
Breakpoint 1 at 0xbca7d0: file ../drivers/net/hns3/hns3_ethdev.c, line 7806.
(gdb) b hns3_dev_close
Breakpoint 2 at 0xbc6d44: file ../drivers/net/hns3/hns3_ethdev.c, line 6189.
(gdb) r
Starting program: 
/home/lihuisong/v500/gcov-test/dpdk/build/app/dpdk-testpmd -a 
0000:7d:00.0 -l 2-3 --file-prefix=rte_lee --proc-type=auto -- -i --rxq 4 
--txq 4 --num-procs=2 --proc-id=1
Missing separate debuginfo for /root/lib/libnuma.so.1
Try: yum --enablerepo='*debug*' install 
/usr/lib/debug/.build-id/ce/4eea0b0f2150f70a080bbd8835e43e78373096.debug
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
EAL: Detected 128 lcore(s)
EAL: Detected 4 NUMA nodes
EAL: Auto-detected process type: SECONDARY
EAL: Detected static linkage of DPDK
[New Thread 0xfffff7a0ad10 (LWP 17717)]
EAL: Multi-process socket /var/run/dpdk/rte_lee/mp_socket_17714_66aa8d3a60a9
[New Thread 0xfffff7209d10 (LWP 17718)]
EAL: Selected IOVA mode 'VA'
EAL: VFIO support initialized
[New Thread 0xfffff69f8d10 (LWP 17719)]
EAL: Using IOMMU type 1 (Type 1)
EAL: Probe PCI driver: net_hns3 (19e5:a222) device: 0000:7d:00.0 (socket 0)
[New Thread 0xfffff61f7d10 (LWP 17720)]
TELEMETRY: No legacy callbacks, legacy socket not created
Interactive-mode selected
0000:7d:00.0 hns3_dev_mtu_set(): Failed to set mtu, port 0 must be 
stopped before configuration
Failed to set MTU to 1500 for port 0
testpmd: create a new mbuf pool <mb_pool_0>: n=155456, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc

Warning! port-topology=paired and odd forward ports number, the last 
port will pair with itself.

Configuring Port 0 (socket 0)
Port 0: 00:18:2D:00:00:9E
Checking link statuses...
Done
testpmd> port close 0
Closing ports...

Breakpoint 2, hns3_dev_close (eth_dev=0x21cdb80 <rte_eth_devices>)
     at ../drivers/net/hns3/hns3_ethdev.c:6189
6189        struct hns3_adapter *hns = eth_dev->data->dev_private;
Missing separate debuginfos, use: debuginfo-install 
glibc-2.17-260.el7.aarch64 libpcap-1.5.3-11.el7.aarch64 
openssl-libs-1.0.2k-16.el7.aarch64 zlib-1.2.7-18.el7.aarch64
(gdb) bt
#0  hns3_dev_close (eth_dev=0x21cdb80 <rte_eth_devices>) at 
../drivers/net/hns3/hns3_ethdev.c:6189
#1  0x0000000000742eac in rte_eth_dev_close (port_id=0) at 
../lib/ethdev/rte_ethdev.c:1870
#2  0x0000000000542a8c in close_port (pid=0) at 
../app/test-pmd/testpmd.c:2895
#3  0x00000000004df82c in cmd_operate_specific_port_parsed 
(parsed_result=0xffffffffb0f0,
     cl=0x2475080, data=0x0) at ../app/test-pmd/cmdline.c:1272
#4  0x0000000000738ce4 in cmdline_parse (cl=0x2475080, buf=0x24750c8 
"port close 0\n")
     at ../lib/cmdline/cmdline_parse.c:290
#5  0x0000000000736b7c in cmdline_valid_buffer (rdl=0x2475090, 
buf=0x24750c8 "port close 0\n",
     size=14) at ../lib/cmdline/cmdline.c:26
#6  0x000000000073c078 in rdline_char_in (rdl=0x2475090, c=10 '\n')
     at ../lib/cmdline/cmdline_rdline.c:421
#7  0x0000000000736fcc in cmdline_in (cl=0x2475080, buf=0xfffffffff25f 
"\n\200\362\377\377\377\377",
     size=1) at ../lib/cmdline/cmdline.c:149
#8  0x0000000000737270 in cmdline_interact (cl=0x2475080) at 
../lib/cmdline/cmdline.c:223
#9  0x00000000004f0ccc in prompt () at ../app/test-pmd/cmdline.c:17882
#10 0x0000000000545528 in main (argc=8, argv=0xfffffffff470) at 
../app/test-pmd/testpmd.c:3998
(gdb) c
Continuing.
Port 0 is closed
Done
testpmd> device detach 0000:7d:00.0
Removing a device...
[Switching to Thread 0xfffff7a0ad10 (LWP 17717)]

Breakpoint 1, hns3_dev_uninit (eth_dev=0x21cdb80 <rte_eth_devices>)
     at ../drivers/net/hns3/hns3_ethdev.c:7806
7806        struct hns3_adapter *hns = eth_dev->data->dev_private;
(gdb) bt
#0  hns3_dev_uninit (eth_dev=0x21cdb80 <rte_eth_devices>) at 
../drivers/net/hns3/hns3_ethdev.c:7806
#1  0x0000000000bb8668 in rte_eth_dev_pci_generic_remove 
(pci_dev=0x247a600,
     dev_uninit=0xbca7c4 <hns3_dev_uninit>) at 
../lib/ethdev/ethdev_pci.h:155
#2  0x0000000000bca89c in eth_hns3_pci_remove (pci_dev=0x247a600)
     at ../drivers/net/hns3/hns3_ethdev.c:7833
#3  0x00000000007e85f4 in rte_pci_detach_dev (dev=0x247a600) at 
../drivers/bus/pci/pci_common.c:287
#4  0x00000000007e8f14 in pci_unplug (dev=0x247a610) at 
../drivers/bus/pci/pci_common.c:570
#5  0x0000000000775678 in local_dev_remove (dev=0x247a610) at 
../lib/eal/common/eal_common_dev.c:319
#6  0x000000000078f114 in __handle_primary_request (param=0xfffff00008c0)
     at ../lib/eal/common/hotplug_mp.c:284
#7  0x000000000079ebf4 in eal_alarm_callback (arg=0x0) at 
../lib/eal/linux/eal_alarm.c:92
#8  0x00000000007a3f30 in eal_intr_process_interrupts 
(events=0xfffff7a0a3e0, nfds=1)
     at ../lib/eal/linux/eal_interrupts.c:998
#9  0x00000000007a4224 in eal_intr_handle_interrupts (pfd=10, totalfds=2)
     at ../lib/eal/linux/eal_interrupts.c:1071
#10 0x00000000007a442c in eal_intr_thread_main (arg=0x0) at 
../lib/eal/linux/eal_interrupts.c:1142
#11 0x0000000000789388 in ctrl_thread_init (arg=0x246ef40)
     at ../lib/eal/common/eal_common_thread.c:202
#12 0x0000fffff7bf3c48 in start_thread () from /lib64/libpthread.so.0
#13 0x0000fffff7b45600 in thread_start () from /lib64/libc.so.6

**************************************************************************************************************************************************

Note: above log is from the secondary process.

>>> And again, please re-consider calling 'rte_eth_dev_close()' or
>>> 'rte_dev_remove()' from the secondary process.
>>>
>>>>>>> +     * Namely, whether "eth_dev" is NULL cannot be used to determine whether
>>>>>>> +     * an ethdev port has been released.
>>>>>>> +     * For both primary process and secondary process, eth_dev->state is
>>>>>>> +     * RTE_ETH_DEV_UNUSED, which means the ethdev port has been released.
>>>>>>> +     */
>>>>>>> +    if (eth_dev->state == RTE_ETH_DEV_UNUSED) {
>>>>>>> +        RTE_ETHDEV_LOG(INFO, "The ethdev port has been released.");
>>>>>>> +        return 0;
>>>>>>> +    }
>>>>> .
>>> .
> .