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

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index fca888b36680df813c952d8d29e1cf74cd81e167..20f954211c617eef04301a8e6d712c19f555ddcc 100644 (file)
--- 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;