Re: [PATCH v2] igb_uio: issue FLR during open and release of device file

[Shijith Thotton <shijith.thotton@caviumnetworks.com>]

On Mon, Jul 10, 2017 at 03:38:34AM +0000, Tan, Jianfeng wrote:
> Hi Thotton,
> 
> > -----Original Message-----
> > From: Shijith Thotton [mailto:shijith.thotton@caviumnetworks.com]
> > Sent: Friday, July 7, 2017 7:14 PM
> > To: dev@dpdk.org
> > Cc: Yigit, Ferruh; Gregory Etelson; Thomas Monjalon; Stephen Hemminger;
> > Tan, Jianfeng; Lu, Wenzhuo
> > Subject: [PATCH v2] igb_uio: issue FLR during open and release of device file
> > 
> > Set UIO info device file operations open and release. Call pci reset
> > function inside open and release to clear device state at start and end.
> > Copied this behaviour from vfio_pci kernel module code. With this patch,
> > it is not mandatory to issue FLR by PMD's during init and close.
> 
> I'm afraid this will not work for restarted DPDK process. In current probe(), we set up the I/O mem and I/O port; and those sys files are used by EAL IGB_UIO initialization code to map I/O mem and port. After reset in release(), we will lose those sys files in next open().
> 
> Thanks,
> Jianfeng
> 
> > 
> > Bus master enable and disable are added in open and release respectively
> > to take care of device DMA.
> > 
> > Signed-off-by: Shijith Thotton <shijith.thotton@caviumnetworks.com>
> > ---
> > v2 changes:
> >  - Replaced pci_try_reset_function with pci_reset_function as it is not
> >    available in older kernel versions.
> > 
> > v1 changes:
> >  - Added pci set master inside open and clear master inside release.
> >  - Remove obvious comments.
> > 
> > RFC: http://dpdk.org/ml/archives/dev/2017-May/066917.html
> > 
> >  lib/librte_eal/linuxapp/igb_uio/igb_uio.c | 33
> > +++++++++++++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> > 
> > diff --git a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
> > b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
> > index b9d427c..07a19a3 100644
> > --- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
> > +++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
> > @@ -170,6 +170,37 @@ struct rte_uio_pci_dev {
> >  	return IRQ_HANDLED;
> >  }
> > 
> > +/**
> > + * This gets called while opening uio device file.
> > + */
> > +static int
> > +igbuio_pci_open(struct uio_info *info, struct inode *inode)
> > +{
> > +	struct rte_uio_pci_dev *udev = info->priv;
> > +	struct pci_dev *dev = udev->pdev;
> > +
> > +	pci_reset_function(dev);
> > +
> > +	/* set bus master, which was cleared by the reset function */
> > +	pci_set_master(dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static int
> > +igbuio_pci_release(struct uio_info *info, struct inode *inode)
> > +{
> > +	struct rte_uio_pci_dev *udev = info->priv;
> > +	struct pci_dev *dev = udev->pdev;
> > +
> > +	/* stop the device from further DMA */
> > +	pci_clear_master(dev);
> > +
> > +	pci_reset_function(dev);
> > +
> > +	return 0;
> > +}
> > +
> >  #ifdef CONFIG_XEN_DOM0
> >  static int
> >  igbuio_dom0_mmap_phys(struct uio_info *info, struct vm_area_struct
> > *vma)
> > @@ -372,6 +403,8 @@ struct rte_uio_pci_dev {
> >  	udev->info.version = "0.1";
> >  	udev->info.handler = igbuio_pci_irqhandler;
> >  	udev->info.irqcontrol = igbuio_pci_irqcontrol;
> > +	udev->info.open = igbuio_pci_open;
> > +	udev->info.release = igbuio_pci_release;
> >  #ifdef CONFIG_XEN_DOM0
> >  	/* check if the driver run on Xen Dom0 */
> >  	if (xen_initial_domain())
> > --
> > 1.8.3.1
>

Hi Jianfeng,

I have tested the patch with LiquidIO VFs in VM using testpmd and could not see
any issue over multiple runs.

Thanks,
Shijith