[dpdk-dev] [PATCH] eal: fix max number of interrupt request

[Zhang, Qi Z]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> Sent: Tuesday, February 14, 2017 5:29 AM
> To: Zhang, Qi Z <qi.z.zhang at intel.com>
> Cc: dev at dpdk.org; Wu, Jingjing <jingjing.wu at intel.com>
> Subject: Re: [PATCH] eal: fix max number of interrupt request
> 
> 2017-02-13 01:16, Zhang, Qi Z:
> > Hi Thomas:
> >
> > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> > > 2017-02-09 14:59, Qi Zhang:
> > > > The max number of interrupt request is possible be changed after
> > > > rte_intr_callback_register, so in get_max_intr, we need to check
> > > > if nessesary to update the max_intr.
> > >
> > > So you are using rte_intr_enable() to update the max_intr field in
> > > the case of VFIO_MSIX.
> > > What about MSI, INTX and UIO cases?
> >
> > My thought is, even without my fix, VFIO_MSIX is already the only case
> > that try to modify max_intr field In get_max_intr, we have:
> > 				if (!src->intr_handle.max_intr)
> >                         src->intr_handle.max_intr = 1;
> >                 else if (src->intr_handle.max_intr >
> RTE_MAX_RXTX_INTR_VEC_ID)
> >                         src->intr_handle.max_intr
> >                                 = RTE_MAX_RXTX_INTR_VEC_ID +
> 1; So my
> > patch just follow this and fix some problem.
> >
> > Another option is I can use a local variable that assigned by max_intr with
> boundary check, so get_max_intr can be totally removed and max_intr in
> intr_source will not be modified.
> >
> > To me both fix are not perfect, I think the problem is in
> rte_intr_callback_register we just save a copy of the pci_dev->intr_handle
> but not the address point, so we are missing some mechanism to sync them.
> > But since we have tight schedule on the 17.02 release and this issue does
> cause some example code can't work, so we need to a fix it first, we may
> consider improve the mechanism later.
> >
> > Thanks
> > Qi
> 
> Applied with this title: "vfio: fix maximum number of interrupt for MSI-X"
> 
> Please check how to document this behaviour and make it consistent with
> other types of interrupts.

OK, I will check.

Thanks
Qi