From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ferruh Yigit Subject: Re: [PATCH] net/nfp: fix lock file usage Date: Thu, 24 May 2018 15:13:36 +0100 Message-ID: References: <1527078536-1443-1-git-send-email-alejandro.lucero@netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: dev , "Varghese, Vipin" To: Alejandro Lucero Return-path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id A85491B05 for ; Thu, 24 May 2018 16:13:40 +0200 (CEST) In-Reply-To: Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 5/24/2018 3:02 PM, Alejandro Lucero wrote: > > > On Thu, May 24, 2018 at 11:18 AM, Ferruh Yigit > wrote: > > On 5/23/2018 5:50 PM, Alejandro Lucero wrote: > > > > > > On Wed, May 23, 2018 at 4:57 PM, Ferruh Yigit > > >> 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 > >> > > > >     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? > > > Time ago I had, by mistake, two different DPDK processes using same device, and > with UIO, there is no one avoiding this. > > You can bound a device to UIO, igb_uio, and then use two different processes > opening the /dev/uiox file, and it works. But this is not anything specific to nfp, isn't it? > > The VFIO driver does avoid this situation, but this lock is required for UIO. >