[dpdk-dev] [PATCH] eal: fix max number of interrupt request
Thomas Monjalon
thomas.monjalon at 6wind.com
Mon Feb 13 22:28:52 CET 2017
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.
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