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

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

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.


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.


Please forgive me because my poor english....



发件人：Ferruh Yigit <ferruh.yigit@intel.com>
发送日期：2020-01-14 22:45:33
收件人：Fang TongHao <fangtonghao@sangfor.com.cn>,thomas@monjalon.net,arybchenko@solarflare.com
抄送人：dev@dpdk.org,stable@dpdk.org,jia.guo@intel.com,cunming.liang@intel.com,qi.z.zhang@intel.com,jungle845943968@outlook.com
主题：Re: [dpdk-dev] [PATCH v2] Fixes: ethdev: secondary process change shared memory>On 1/13/2020 5:03 AM, Fang TongHao wrote:
>> Secondary process calls “rte_eth_dev_pci_allocate”
>> function and enters rte_eth_copy_pci_info function
>> when initializing.Then it sets the value of struct
>> "rte_eth_dev_data.dev_flags" to zero and reset it,
>> but this struct is shared by primary process and
>> secondary process.To fix this bug,by adding an
>> if-statement to forbid the secondaryprocess changing
>> the above-mentioned value.
>
>Hi Fang,
>
>Thanks for the fix, I agree with the problem statement, but not sure if this
>should be handled in the helper function or in the place where the function is
>called. Helper function is simple on what it does, do we need to put the primary
>process logic in it.
>
>Can you please give more details of the bug you have encounter, is it seen by a
>specific PMD?
>
>Thanks,
>ferruh
>
>> 
>> Signed-off-by: Fang TongHao <fangtonghao@sangfor.com.cn>
>> ---
>>  lib/librte_ethdev/rte_ethdev_pci.h | 18 ++++++++++--------
>>  1 file changed, 10 insertions(+), 8 deletions(-)
>> 
>> diff --git a/lib/librte_ethdev/rte_ethdev_pci.h b/lib/librte_ethdev/rte_ethdev_pci.h
>> index ccdbb46ec..e7dae0545 100644
>> --- a/lib/librte_ethdev/rte_ethdev_pci.h
>> +++ b/lib/librte_ethdev/rte_ethdev_pci.h
>> @@ -60,14 +60,16 @@ rte_eth_copy_pci_info(struct rte_eth_dev *eth_dev,
>>  
>>  	eth_dev->intr_handle = &pci_dev->intr_handle;
>>  
>> -	eth_dev->data->dev_flags = 0;
>> -	if (pci_dev->driver->drv_flags & RTE_PCI_DRV_INTR_LSC)
>> -		eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_LSC;
>> -	if (pci_dev->driver->drv_flags & RTE_PCI_DRV_INTR_RMV)
>> -		eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_RMV;
>> -
>> -	eth_dev->data->kdrv = pci_dev->kdrv;
>> -	eth_dev->data->numa_node = pci_dev->device.numa_node;
>> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
>> +		eth_dev->data->dev_flags = 0;
>> +		if (pci_dev->driver->drv_flags & RTE_PCI_DRV_INTR_LSC)
>> +			eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_LSC;
>> +		if (pci_dev->driver->drv_flags & RTE_PCI_DRV_INTR_RMV)
>> +			eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_RMV;
>> +
>> +		eth_dev->data->kdrv = pci_dev->kdrv;
>> +		eth_dev->data->numa_node = pci_dev->device.numa_node;
>> +	}
>>  }
>>  
>>  static inline int
>> 
>