Re: [dpdk-dev] [PATCH] bus/pci: fix wrong intr_handle.type with uio_pci_generic

["Yang, Zhiyong" <zhiyong.yang@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Thursday, December 28, 2017 6:49 PM
> To: Yang, Zhiyong <zhiyong.yang@intel.com>
> Cc: dev@dpdk.org; Yigit, Ferruh <ferruh.yigit@intel.com>; stable@dpdk.org
> Subject: Re: [PATCH] bus/pci: fix wrong intr_handle.type with uio_pci_generic
> 
> 28/12/2017 10:37, Yang, Zhiyong:
> > Hi Thomas,
> >
> > > -----Original Message-----
> > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > Sent: Thursday, December 28, 2017 5:05 PM
> > > To: Yang, Zhiyong <zhiyong.yang@intel.com>
> > > Cc: dev@dpdk.org; Yigit, Ferruh <ferruh.yigit@intel.com>;
> > > stable@dpdk.org
> > > Subject: Re: [PATCH] bus/pci: fix wrong intr_handle.type with
> > > uio_pci_generic
> > >
> > > 28/12/2017 07:12, Zhiyong Yang:
> > > > In the function rte_pci_ioport_map, if uio_pci_generic is used on
> > > > X86 platform, pci_ioport_map() is invoked, the operation
> > > > ev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN; is execused
> > > > ev->directly,
> > > > it causes the wrong assignment for uio_pci_generic, the patch fixes it.
> > > [...]
> > > > --- a/drivers/bus/pci/linux/pci.c
> > > > +++ b/drivers/bus/pci/linux/pci.c
> > > > @@ -723,7 +723,9 @@ pci_ioport_map(struct rte_pci_device *dev, int
> > > > bar
> > > __rte_unused,
> > > >  	if (!found)
> > > >  		return -1;
> > > >
> > > > -	dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
> > > > +	if (dev->kdrv == RTE_KDRV_NONE)
> > > > +		dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
> > >
> > > I don't understand the logic.
> > > NONE is different of UNKNOWN.
> > >
> > > Your are talking about uio_pci_generic. In this case, it should be
> > > RTE_KDRV_UIO_GENERIC.
> >
> > If we use uio_pci_generic,  dev->intr_handle.type has already been
> > assigned to The right value RTE_INTR_HANDLE_UIO_INTX before it, but in
> > the function pci_ioport_map the wrong value is assigned to
> > dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN; Two cases both call
> pci_ioport_map  on x86 platform.
> > one is RTE_KDRV_UIO_GENERIC
> > the other is RTE_KDRV_NONE
> > if I understand right, for uio_generic, it should not be assigned to
> > RTE_INTR_HANDLE_UNKNOWN; This case has already the right value, don't
> need to assign again.
> > The original code should be considered to handle RTE_KDRV_NONE case only.
> 
> OK thanks for the explanation.
> I had overlooked your patch.
> 
> Please, could add some of this text in v2?
> I think it is good to explain that the right value is already set, and we must avoid
> overwriting the default "UNKNOWN" value.

Ok.  add the text in V2 later.

> 
> One more question, why is it needed to set the value to "UNKNOWN" in this
> function? It should already be set to this value (0) at init.

Good suggestion, we should remove it to fix issue . Any different opinion?  Everyone.

BTW,  The bug can be seen if run the following test case.

Testpmd startup fails  using uio_pci_generic running on virtio legacy device.

Thanks
Zhiyong