Re: [dpdk-dev] [PATCH] net/nfp: fix lock file usage

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/23/2018 5:50 PM, Alejandro Lucero wrote:
> 
> 
> On Wed, May 23, 2018 at 4:57 PM, Ferruh Yigit <ferruh.yigit@intel.com
> <mailto:ferruh.yigit@intel.com>> wrote:
> 
>     On 5/23/2018 1:28 PM, Alejandro Lucero wrote:
>     > DPDK apps can be executed as non-root users but current NFP lock
>     > file for avoiding concurrent accesses to CPP interface is precluding
>     > this option or requires to modify system file permissions.
>     > 
>     > When the NFP device is bound to VFIO, this driver does not allow this
>     > concurrent access, so the lock file is not required at all.
>     > 
>     > OVS-DPDK as executed in RedHat distributions is the main NFP user
>     > needing this fix.
>     > 
>     > Fixes: c7e9729da6b5 ("net/nfp: support CPP")
>     > 
>     > Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com <mailto:alejandro.lucero@netronome.com>>
> 
>     Hi Alejandro,
> 
>     As far as I understand this is to fix a common use case for nfp, but it looks
>     like there is already a workaround and only for non-root users.
> 
> 
> There is a patch submitted to stable versions because this lock was also with
> the old NSPU interface, but as far as I know, there is no patch yet for the
> current upstream tip.
> 
>  
> 
>     What is the priority of the patch, only critical but fixes allowed at this
>     point, can we push this one to next release?
> 
> 
> This is critical for us because RedHat wants to support OVS with our card, and
> when OVS-DPDK is used, this problem is precluding non-root users to execute
> OVS-DPDK.

What exactly this lock for? Does it to prevent multiple primary process to
access CPP interface?

If so this is the know limitation in DPDK, not two separate process can driver
same hardware, this is valid for all devices, why adding a lock unique to nfp?