Re: [dpdk-dev] [PATCH] eal: Fixes VFIO/sysfs race condition

["Haeuptle, Michael" <michael.haeuptle@hpe.com>]

Hi Dave,

This is my first submission... how do I get the fixes reference?

Back porting it to 19.11 would be great. This issue shows up in SPDK 20.01, which uses 19.11.

-- Michael

-----Original Message-----
From: David Marchand [mailto:david.marchand@redhat.com] 
Sent: Monday, April 6, 2020 7:25 AM
To: Burakov, Anatoly <anatoly.burakov@intel.com>; Haeuptle, Michael <michael.haeuptle@hpe.com>
Cc: dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] eal: Fixes VFIO/sysfs race condition

On Thu, Apr 2, 2020 at 12:11 PM Burakov, Anatoly <anatoly.burakov@intel.com> wrote:
>
> On 31-Mar-20 5:56 PM, Michael Haeuptle wrote:
> > This fix treats a 0 return value from vfio_open_group_fd in 
> > vfio_get_group_fd as the intended error condition instead of putting 
> > an incorrect 0 file descriptor in the vfio_group table.
> >
> > Sometimes, the creation of device files in sysfs is not 
> > instantaneously causing vfio_open_groupfd to return 0.
> > This has been observed when hot removing/adding multiple NVMe 
> > devices (>=4).
> >
> > Signed-off-by: Michael Haeuptle <michael.haeuptle@hpe.com>
> > ---
> >   lib/librte_eal/linux/eal_vfio.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/librte_eal/linux/eal_vfio.c 
> > b/lib/librte_eal/linux/eal_vfio.c index 4502aefed..1979f6fdd 100644
> > --- a/lib/librte_eal/linux/eal_vfio.c
> > +++ b/lib/librte_eal/linux/eal_vfio.c
> > @@ -379,7 +379,7 @@ vfio_get_group_fd(struct vfio_config *vfio_cfg,
> >       }
> >
> >       vfio_group_fd = vfio_open_group_fd(iommu_group_num);
> > -     if (vfio_group_fd < 0) {
> > +     if (vfio_group_fd <= 0) {
> >               RTE_LOG(ERR, EAL, "Failed to open group %d\n", iommu_group_num);
> >               return -1;
> >       }
> >
>
> If it's returning an invalid value, is that a kernel bug?
>
> I mean, looks fine to me, so
>
> Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

We are missing a fixes line.
Does this deserve a backport?


--
David Marchand