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....@linaro.org>

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....@linaro.org>
Cc: Ganapatrao Kulkarni <ganapatrao.kulka...@cavium.com>
Cc: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
---

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