[dpdk-dev] [PATCH] igb_uio: remove device reset in open

Mody, Rasesh Rasesh.Mody at cavium.com
Thu Nov 2 09:03:21 CET 2017


> From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> Sent: Wednesday, November 01, 2017 7:12 AM
> 
> On Wed, 1 Nov 2017 06:58:53 +0000
> "Mody, Rasesh" <Rasesh.Mody at cavium.com> wrote:
> 
> > Hi Jianfeng and Ferruh,
> >
> > > From: Ferruh Yigit [mailto:ferruh.yigit at intel.com]
> > > Sent: Thursday, October 26, 2017 5:50 PM
> > >
> > > On 10/26/2017 2:28 AM, Tan, Jianfeng wrote:
> > > > Hi Rasesh,
> > > >
> > > >
> > > > On 10/26/2017 7:43 AM, Mody, Rasesh wrote:
> > > >> Hi Ferruh,
> > > >>
> > > >>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ferruh
> > > >>> Yigit
> > > >>> Sent: Friday, October 20, 2017 9:58 AM
> > > >>>
> > > >>> On 10/20/2017 9:55 AM, Ferruh Yigit wrote:
> > > >>>> Remove device reset during application start, the reset for
> > > >>>> application exit still there.
> > > >>>>
> > > >>>> Reset in open removed because of following comments:
> > > >>>> 1- Device reset not completed when VF driver loaded, which
> > > >>>> cause VF
> > > PMD
> > > >>>>     initialization error.
> > > >>>>     Adding delay can solve the issue but will increase driver load time.
> > > >>>>
> > > >>>> 2- Reset will be issues all devices unconditionally, not very efficient
> > > >>>>     way.
> > > >>>>
> > > >>>> Fixes: b58eedfc7dd5 ("igb_uio: issue FLR during open and
> > > >>>> release of device file")
> > > >>>> Cc: stable at dpdk.org
> > > >>>>
> > > >>>> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
> > > >>> Hi Jingjing, Shijith, Gregory, Harish,
> > > >>>
> > > >>> Can you please test this on top of current master (which has
> > > >>> already Jingjin's
> > > >>> fix) ?
> > > >> The original FLR change during igb_uio open()/release() in
> > > >> DPDK17.08 also
> > > impacts BNX2X PMD and it exhibits the issues with bare metal testing.
> > > >>
> > > >> Now, we tested this change for BNX2X PMD using latest dpdk, which
> > > >> has
> > > this fix where FLR is invoked only in the release().
> > >
> > > Good to hear this fixed the problem.
> >
> > Yes, it fixed the issue caused by pci reset during application start.
> >
> > >
> > > >> However, we ran into an issue when trying to reload the testpmd
> > > application in quick succession. The pci reset, called during the
> > > igb_uio
> > > release() operation, is taking longer time and adapter is still
> > > doing the FLR when we relaunch the application. We see this behavior
> > > with bare metal testing.
> > > >
> > > > If we don't reset that device, it will continue working which is a
> > > > more serious issue IMO.
> > >
> > > +1
> >
> > I think, it would better for the individual PMDs to take care of the reset
> during the application exit.
> 
> That will never be possible. Poll Mode Drivers are userspace entities and part
> of the application. If application crashes, there is no way for PMD to do
> cleanup, it must be handled by kernel.

The pci reset in release is breaking the BNX2X PMD. Could we revert this reset and get it included with a solution that works for all in the next release?

Thanks!
-Rasesh


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