From: Fushuai Wang <redacted>

When an SF is created after a CPU has been taken offline, the IRQ pool may
contain IRQs with affinity masks that include the offline CPU. Since only
online CPUs should be considered for IRQ placement, cpumask_subset() check
would fail because the iter_mask contains offline CPUs that are not present
in req_mask, causing SF creation to fail.

Use irq_get_effective_affinity_mask() instead, which returns the IRQ's
actual effective affinity that already excludes offline CPUs.

Fixes: 061f5b23588a ("net/mlx5: SF, Use all available cpu for setting cpu affinity")
Suggested-by: Shay Drory <redacted>
Signed-off-by: Fushuai Wang <redacted>
---
 drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
index 994fe83da4be..c5d784cbc8e4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c

@@ -105,9 +105,12 @@ irq_pool_find_least_loaded(struct mlx5_irq_pool *pool, const struct cpumask *req
 
 	lockdep_assert_held(&pool->lock);
 	xa_for_each_range(&pool->irqs, index, iter, start, end) {
-		struct cpumask *iter_mask = mlx5_irq_get_affinity_mask(iter);
+		const struct cpumask *iter_mask;
 		int iter_refcount = mlx5_irq_read_locked(iter);
 
+		iter_mask = irq_get_effective_affinity_mask(mlx5_irq_get_irq(iter));
+		if (!iter_mask)
+			continue;
 		if (!cpumask_subset(iter_mask, req_mask))
 			/* skip IRQs with a mask which is not subset of req_mask */
 			continue;

-- 
2.36.1