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

[Mody, Rasesh]

> From: Ferruh Yigit [mailto:ferruh.yigit at intel.com]
> Sent: Thursday, November 02, 2017 11:10 AM
> 
> On 11/2/2017 10:34 AM, Mody, Rasesh wrote:
> >> From: Ferruh Yigit [mailto:ferruh.yigit at intel.com]
> >> Sent: Thursday, November 02, 2017 1:55 AM
> >>
> >> On 11/2/2017 1:03 AM, Mody, Rasesh wrote:
> >>>> 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?
> >>
> >> Hi Rasesh,
> >>
> >> I am not sure if there is more to do for solution for next releases,
> >> and related to your case, indeed I wasn't expecting a device reset
> >> will take more than five minutes...
> >>
> >> Would you be OK to control the reset via a compile time config
> >> option, which is enabled by default. So you will need to disable it to
> prevent the reset?
> >
> > Hi Ferruh,
> >
> > As I understand, we will have a compile time config option, enabled by
> default, to guard the pci_reset_function() in the igbuio_pci_release(). We
> will disable this config option to prevent the reset when using BNX2X.
> 
> Yep, this is the idea.
> 
> > The controlled reset should work for us.
> 
> If there is no objection, I can send a patch for this.

We are ok as we have at least some way to disable the reset, please send a patch.

Thanks!
-Rasesh