Thanks for pointing it out. Fix it in v3.
BRs,
Xiao
> -----Original Message-----
> From: Bie, Tiwei
> Sent: Tuesday, December 19, 2017 5:05 PM
> To: Wang, Xiao W <xiao.w.w...@intel.com>
> Cc: Yigit, Ferruh <ferruh.yi...@intel.com>; dev@dpdk.org;
> step...@networkplumber.org
> Subject: Re: [dpdk-dev] [PATCH v2] igb_uio: allow multi-process access
>
> Hi,
>
> On Tue, Dec 19, 2017 at 07:42:20AM -0800, Xiao Wang wrote:
> > @@ -336,6 +337,10 @@ struct rte_uio_pci_dev {
> > struct pci_dev *dev = udev->pdev;
> > int err;
> >
> > + atomic_inc(&udev->refcnt);
> > + if (atomic_read(&udev->refcnt) > 1)
>
> The "inc and read" should be atomic. Otherwise below
> sequence may happen:
>
> P1: atomic_inc(&udev->refcnt);
> P2: atomic_inc(&udev->refcnt);
> P1: if (atomic_read(&udev->refcnt) > 1)
> P2: if (atomic_read(&udev->refcnt) > 1)
>
> > + return 0;
> > +
> > /* set bus master, which was cleared by the reset function */
> > pci_set_master(dev);
> >
> > @@ -354,6 +359,10 @@ struct rte_uio_pci_dev {
> > struct rte_uio_pci_dev *udev = info->priv;
> > struct pci_dev *dev = udev->pdev;
> >
> > + atomic_dec(&udev->refcnt);
> > + if (atomic_read(&udev->refcnt) > 0)
> > + return 0;
>
> Ditto.
>
> Best regards,
> Tiwei Bie
>
> > +
> > /* disable interrupts */
> > igbuio_pci_disable_interrupts(udev);
> >
> > --
> > 1.8.3.1
> >
