Re: [PATCH v2] irqchip/gic-v3-its: Allow GIC ITS number more than MAX_NUMNODES

[Hanjun Guo]

On 2017/7/25 19:02, John Garry wrote:
> On 22/07/2017 04:54, Hanjun Guo wrote:
> > From: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> >
> > When running 4.13-rc1 on top of D05, I got the boot log:
> >
> > [    0.000000] SRAT: PXM 0 -> ITS 0 -> Node 0
> > [    0.000000] SRAT: PXM 0 -> ITS 1 -> Node 0
> > [    0.000000] SRAT: PXM 0 -> ITS 2 -> Node 0
> > [    0.000000] SRAT: PXM 1 -> ITS 3 -> Node 1
> > [    0.000000] SRAT: ITS affinity exceeding max count[4]
> >
> > This is wrong on D05 as we have 8 ITSes with 4 NUMA nodes.
> >
> > So dynamically alloc the memory needed instead of using
> > its_srat_maps[MAX_NUMNODES], which count the number of
> > ITS entry(ies) in SRAT and alloc its_srat_maps as needed,
> > then build the mapping of numa node to ITS ID. Of course,
> > its_srat_maps will be freed after ITS probing because
> > we don't need that after boot.
> >
> > After doing this, I got what I wanted:
> >
> > [    0.000000] SRAT: PXM 0 -> ITS 0 -> Node 0
> > [    0.000000] SRAT: PXM 0 -> ITS 1 -> Node 0
> > [    0.000000] SRAT: PXM 0 -> ITS 2 -> Node 0
> > [    0.000000] SRAT: PXM 1 -> ITS 3 -> Node 1
> > [    0.000000] SRAT: PXM 2 -> ITS 4 -> Node 2
> > [    0.000000] SRAT: PXM 2 -> ITS 5 -> Node 2
> > [    0.000000] SRAT: PXM 2 -> ITS 6 -> Node 2
> > [    0.000000] SRAT: PXM 3 -> ITS 7 -> Node 3
> >
> > Fixes: dbd2b8267233 ("irqchip/gic-v3-its: Add ACPI NUMA node mapping")
> > Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> > Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> > ---
> >
> > v1->v2:
> >   - Add NULL check in acpi_get_its_numa_node() for no ITS affinity case;
> >   - Free the its_srat_maps after ITS probing.
> >
> >  drivers/irqchip/irq-gic-v3-its.c | 39 
> > ++++++++++++++++++++++++++++++++-------
> >  1 file changed, 32 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c 
> > b/drivers/irqchip/irq-gic-v3-its.c
> > index 3ccdf76..1d692aa 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -1847,13 +1847,16 @@ struct its_srat_map {
> >      u32    its_id;
> >  };
> >
> > -static struct its_srat_map its_srat_maps[MAX_NUMNODES] __initdata;
> > +static struct its_srat_map *its_srat_maps __initdata;
> >  static int its_in_srat __initdata;
> >
> >  static int __init acpi_get_its_numa_node(u32 its_id)
> >  {
> >      int i;
> >
> > +    if (!its_srat_maps)
> > +        return NUMA_NO_NODE;
>
> Question: Does !its_srat_maps always imply its_in_srat == 0, so we could 
> just fall through the for loop and return NUMA_NO_NODE without this check?
>
> Or should we be safe/explicit/or falling through loops is a bad coding 
> style?

Hmm, you are right, I missed that point, its_in_srat will
always be 0 if its_srat_maps be NULL, removed the NULL
check and tested it on D03 (without ITS NUMA) and D03 boots
OK, will remove the check in the new version.

Thanks
Hanjun