Re: [dpdk-dev] [PATCH v2] Fixes: ethdev: secondary process change shared memory

[方统浩50450 <fangtonghao@sangfor.com.cn>]

ok, I send a new version of my patch and rewrite commit log again.
you can check my patch in https://patches.dpdk.org/patch/64819/






发件人：Ferruh Yigit <ferruh.yigit@intel.com>
发送日期：2020-01-16 20:18:18
收件人："方统浩50450" <fangtonghao@sangfor.com.cn>
抄送人：Andrew Rybchenko <arybchenko@solarflare.com>,Thomas Monjalon <thomas@monjalon.net>,dev@dpdk.org,stable@dpdk.org,jia.guo@intel.com,cunming.liang@intel.com,qi.z.zhang@intel.com,jungle845943968@outlook.com,Jerin Jacob Kollanukkaran <jerinj@marvell.com>
主题：Re: [dpdk-dev] [PATCH v2] Fixes: ethdev: secondary process change shared memory>On 1/16/2020 11:35 AM, 方统浩50450 wrote:
>> 
>> 
>>>@Fang, only can you please make a new version to update the
>>>'rte_eth_copy_pci_info' function comment to document shared data is not updated
>>>for the secondary process?
>> 
>>>So this suggest going on with Fang's patch. I only requested an additional note
>>>in function comment related to this secondary check.
>> 
>> @Ferruh Yigit
>> Should I update a new version patch of "rte_eth_copy_pci_info" function and explain
>> wthether the regular functioning of secondary process is affected or not?
>> I cant figure out what you need me to do.
>
>Hi Fang,
>
>Yes can you please send a new version of your patch.
>In new version, additionally update the 'rte_eth_copy_pci_info()' function
>comment to document that function updates 'eth_dev->data' only for primary process.
>
>Thanks,
>ferruh
>
>> 
>> 
>> 发件人：Ferruh Yigit <ferruh.yigit@intel.com>
>> 发送日期：2020-01-16 17:04:09
>> 收件人：Andrew Rybchenko <arybchenko@solarflare.com>,Thomas Monjalon <thomas@monjalon.net>
>> 抄送人："方统浩50450" <fangtonghao@sangfor.com.cn>,dev@dpdk.org,stable@dpdk.org,jia.guo@intel.com,cunming.liang@intel.com,qi.z.zhang@intel.com,jungle845943968@outlook.com,Jerin Jacob Kollanukkaran <jerinj@marvell.com>
>> 主题：Re: [dpdk-dev] [PATCH v2] Fixes: ethdev: secondary process change shared memory>On 1/16/2020 7:43 AM, Andrew Rybchenko wrote:
>>>> On 1/15/20 11:43 PM, Thomas Monjalon wrote:
>>>>> 15/01/2020 19:35, Ferruh Yigit:
>>>>>> On 1/15/2020 6:49 AM, 方统浩50450 wrote:
>>>>>>> Hi Ferruh, thanks for your message.
>>>>>>>
>>>>>>>
>>>>>>> We developed a ethtool-dpdk which is secondary process based dpdk 17.08 version. Our device
>>>>>>> support hotplug detach, but hotplug deatch is failed when we use ethtool-dpdk.We found the
>>>>>>> secondary process will change the shared memory when initializing.Secondary process calls
>>>>>>> "rte_eth_dev_pci_allocate" function and enters "rte_eth_copy_pci_info" function.
>>>>>>> (rte_eth_dev_pci_generic_probe -> rte_eth_dev_pci_allocate -> rte_eth_copy_pci_info)
>>>>>>> Then it sets the value of struct "rte_eth_dev_data.dev_flags" to zero.In our platform, this value
>>>>>>> is equal to 0x0003.(RTE_ETH_DEV_DETACHABLE | RTE_ETH_DEV_INTR_LSC),but after reset
>>>>>>> the "dev_flags", the value changed to 0x0002.(RTE_ETH_DEV_DETACHABLE).So, our device hotplug
>>>>>>> detach is failed.I found the similar problem in other dpdk version, include dpdk 19.11.Even though
>>>>>>> the deivce hotplug detach is discarded,but i think the shared memory changed is unexpected by primary
>>>>>>> process.
>>>> 
>>>> Hold on, just for my understanding. As far as I can see
>>>> RTE_ETH_DEV_DETACHABLE was removed in 17.11. Does it
>>>> change something in above description?
>>>
>>>Overall secondary overwrites primary values, I think we should fix it
>>>independent from the flags involved.
>>>
>>>> 
>>>>>> I agree this is the problem.
>>>>>> In the driver code, 'rte_eth_copy_pci_info' is called only by primary process,
>>>>>>
>>>>>> but the generic code is faulty.
>>>>>>
>>>>>> And in 19.11 additionally 'eth_dev_pci_specific_init' also seems has same problem.
>>>> 
>>>> Yes, as I understand RTE_ETH_DEV_CLOSE_REMOVE,
>>>> RTE_ETH_DEV_BONDED_SLAVE, RTE_ETH_DEV_REPRESENTOR and
>>>> RTE_ETH_DEV_NOLIVE_MAC_ADDR may be lost because of
>>>> reinit (if not restored in other branches). Bad anyway.
>>>> 
>>>>>>> Our driver is ixgbe, i think this problem has a little relationship with driver, Secondary process
>>>>>>> enters "rte_eth_copy_pci_info" by "rte_eth_dev_pci_allocate".And I agree your opinion, the helper
>>>>>>> function should simple on what it does.I have two ways to fix this problem, one is add an if-statement
>>>>>>>
>>>>>>> in "rte_eth_dev_pci_allocate" function to forbid secondary process enters "rte_eth_copy_pci_info" function,
>>>>>>> another way is add an if-statement in "rte_eth_copy_pci_info" function to forbid secondary process change
>>>>>>> shared memory.And First way need to ensure the "rte_eth_copy_pci_info" function won't be called anywhere else.
>>>>>>> I think the second way is simple and lower risk.
>>>>>>
>>>>>> Yes these are the two options.
>>>>>>
>>>>>> I agree adding check in the 'rte_eth_copy_pci_info' covers all cases and safer.
>>>>>> BUT my concern was adding decision making to simple/leaf function and make it
>>>>>> harder to debug/use, instead of giving what primary/secondary process should
>>>>>> call decision in higher level.
>>>>>>
>>>>>> But I just recognized that some PMDs are calling 'rte_eth_copy_pci_info' on
>>>>>> secondary process, like mlx4 or szedata2, and most probably this is not their
>>>>>> intention.
>>>>>> And 'eth_dev->intr_handle' set in 'rte_eth_copy_pci_info', not calling this
>>>>>> function may have side affect of 'eth_dev->intr_handle' not set in secondary.
>>>>>>
>>>>>> With above considerations I am OK to your proposal to cover all cases, Thomas,
>>>>>> Andrew, any concern?
>>>> 
>>>> I would put if condition in rte_eth_copy_pci_info().
>>>> It is the function which writes shared space from
>>>> secondary process when it should not be done and it
>>>> should be fixed there.
>>>
>>>OK
>>>
>>>> 
>>>>> Do you mean drivers need to be fixed?
>>>> 
>>>> I'm not sure that I fully understand it. Since copy function
>>>> cares about intr_handle copying I'm afraid that it is not
>>>> 100% correct to skip it in secondary process completely as
>>>> many drivers do right now. Basically it makes eth_dev structure
>>>> in secondary process inconsistent. However, it looks like
>>>> most of these drivers simply obtain handle from pci_dev
>>>> directly and it explains why they are not affected.
>>>> There are exceptions which are potentially bugs, e.g.
>>>> drivers/net/ice/ice_ethdev.c: ice_interrupt_handler at the end.
>>>> 
>>>> I think that it would be better if intr_handle is always
>>>> correct in eth_dev (both primary and secondary cases) and
>>>> drivers use it instead of the same from pci_dev.
>>>> 
>>>
>>>OK
>>>
>>>So this suggest going on with Fang's patch. I only requested an additional note
>>>in function comment related to this secondary check.
>> 
>> 
>