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The following commit has been merged into the irq/core branch of tip:

Commit-ID: fcb8af4cbcd122e33ceeadd347b8866d32035af7
Gitweb: https://git.kernel.org/tip/fcb8af4cbcd122e33ceeadd347b8866d32035af7
Author: Dawei Li <dawei.li@shingroup.cn>
AuthorDate: Tue, 16 Apr 2024 16:54:50 +08:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 24 Apr 2024 21:23:49 +02:00

irqchip/gic-v3-its: Avoid explicit cpumask allocation on stack

In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Remove cpumask var on stack and use cpumask_any_and() to address it.

Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240416085454.3547175-4-dawei.li@shingroup.cn

---
drivers/irqchip/irq-gic-v3-its.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index fca888b..20f9542 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -3826,9 +3826,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
bool force)
{
struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
- struct cpumask common, *table_mask;
+ unsigned int from, cpu = nr_cpu_ids;
+ struct cpumask *table_mask;
unsigned long flags;
- int from, cpu;

/*
* Changing affinity is mega expensive, so let's be as lazy as
@@ -3850,10 +3850,15 @@ static int its_vpe_set_affinity(struct irq_data *d,
* If we are offered another CPU in the same GICv4.1 ITS
* affinity, pick this one. Otherwise, any CPU will do.
*/
- if (table_mask && cpumask_and(&common, mask_val, table_mask))
- cpu = cpumask_test_cpu(from, &common) ? from : cpumask_first(&common);
- else
+ if (table_mask)
+ cpu = cpumask_any_and(mask_val, table_mask);
+ if (cpu < nr_cpu_ids) {
+ if (cpumask_test_cpu(from, mask_val) &&
+ cpumask_test_cpu(from, table_mask))
+ cpu = from;
+ } else {
cpu = cpumask_first(mask_val);
+ }

if (from == cpu)
goto out;