Re: [dpdk-users] [dpdk-dev] IGB_UIO: PCI Resources Management

[Alejandro Lucero <alejandro.lucero@netronome.com>]

I completely misread the patch, and I wrongly thought that code was linked
to module removal, but I see this is not about that, but about releasing
the /dev/uio file calling release function, what is done by the kernel when
the process exits.

So yes, the patch avoids the problem I talked about.

However, calling that specific ixgbe driver function will break other
devices relying on igb_uio. What about implementing a notifier chain for
this? The igb_uio code would be agnostic and each interested driver, like
ixgbe or nfp_net, could execute the specific port close code when the
notifier chain triggers.


On Fri, Jan 13, 2017 at 5:33 AM, Tan, Jianfeng <jianfeng.tan@intel.com>
wrote:

>
>
> > -----Original Message-----
> > From: Yigit, Ferruh
> > Sent: Friday, January 13, 2017 10:05 AM
> > To: Tan, Jianfeng; Alejandro Lucero
> > Cc: Gregory Etelson; dev; users@dpdk.org
> > Subject: Re: [dpdk-users] [dpdk-dev] IGB_UIO: PCI Resources Management
> >
> > On 1/13/2017 1:51 AM, Tan, Jianfeng wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: users [mailto:users-bounces@dpdk.org] On Behalf Of Ferruh Yigit
> > >> Sent: Thursday, January 12, 2017 8:22 PM
> > >> To: Alejandro Lucero
> > >> Cc: Gregory Etelson; dev; users@dpdk.org
> > >> Subject: Re: [dpdk-users] [dpdk-dev] IGB_UIO: PCI Resources
> > Management
> > >>
> > >> On 1/12/2017 12:12 PM, Alejandro Lucero wrote:
> > >>>
> > >>>
> > >>> On Thu, Jan 12, 2017 at 11:55 AM, Ferruh Yigit <
> ferruh.yigit@intel.com
> > >>> <mailto:ferruh.yigit@intel.com>> wrote:
> > >>>
> > >>>     On 12/9/2016 8:54 AM, Gregory Etelson wrote:
> > >>>     > Hello,
> > >>>     >
> > >>>     > IGB_UIO driver does not close port PCI activities after DPDK
> process
> > >> exits.
> > >>>     > DPDK API provides rte_eth_dev_close() to manage port PCI,
> > >>>     > but it can be skipped if process receives SIGKILL signal
> > >>>
> > >>>     I guess I understand the problem.
> > >>>
> > >>>
> > >>> This is a known problem, but it is not just a UIO problem, and this
> > >>> patch does not solve it, maybe it just solves part of it.
> > >>>
> > >>> In fact, a DPDK program crashing could imply the NIC DMAing after
> that
> > >>> and after that memory was assigned to another program.
> > >>
> > >> Yes.
> > >> Can there be a way to stop NIC DMA, (or prevent it access to mem
> > >> anymore) when app crashes?
> > >> I think that is what this patch is looking for.
> > >
> > > If I understand it correctly, you are looking for this patch?
> > > http://dpdk.org/dev/patchwork/patch/17495/
> > >
> >
> > That is good, thanks Jianfeng, I will check it.
> >
> > btw, patch's current state is rejected, which is by mistake, it seems I
> > confused it with "iomem and ioport mapping" patch, sorry about it, I
> > will update its status immediately.
>
> No problem at all. This patch is rejected as it's based on "iomem and
> ioport mapping" patch. As "iomem and ioport mapping" patch has backward
> compatibility issue, we need to figure out a way to resubmit this patch
> without changing the original "iomem and ioport mapping" in igb_uio.
>
> Thanks,
> Jianfeng
>