Subject: [PATCHv2 rdma-next 1/1] net/mlx5: Fix build -Wframe-larger-than warnings

From: Zhu Yanjun <[email-masked]>
Date: Fri, 11 Jul 2025 05:03:59 +0200

When building, the following warnings will appear.
"
pci_irq.c: In function ‘mlx5_ctrl_irq_request’:
pci_irq.c:494:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

pci_irq.c: In function ‘mlx5_irq_request_vector’:
pci_irq.c:561:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

eq.c: In function ‘comp_irq_request_sf’:
eq.c:897:1: warning: the frame size of 1080 bytes is larger than 1024 bytes [-Wframe-larger-than=]

irq_affinity.c: In function ‘irq_pool_request_irq’:
irq_affinity.c:74:1: warning: the frame size of 1048 bytes is larger than 1024 bytes [-Wframe-larger-than=]
"

These warnings indicate that the stack frame size exceeds 1024 bytes in
these functions.

To resolve this, instead of allocating large memory buffers on the stack,
it is better to use kvzalloc to allocate memory dynamically on the heap.
This approach reduces stack usage and eliminates these frame size warnings.

Signed-off-by: Zhu Yanjun <[email-masked]>
---
v1 -> v2: Add kvfree to error handler;

1. This commit only build tests;
2. All the changes are on configuration path, will not make difference
on the performance;
3. This commit is just to fix build warnings, not error or bug fixes. So
not Fixes tag.
---
 drivers/net/ethernet/mellanox/mlx5/core/eq.c  | 24 +++++++----
 .../mellanox/mlx5/core/irq_affinity.c         | 19 +++++++--
 .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 40 +++++++++++++------
 3 files changed, 60 insertions(+), 23 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
index dfb079e59d85..4938dd7c3a09 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
@@ -873,19 +873,29 @@ static int comp_irq_request_sf(struct mlx5_core_dev *dev, u16 vecidx)
 {
 	struct mlx5_irq_pool *pool = mlx5_irq_table_get_comp_irq_pool(dev);
 	struct mlx5_eq_table *table = dev->priv.eq_table;
-	struct irq_affinity_desc af_desc = {};
+	struct irq_affinity_desc *af_desc;
 	struct mlx5_irq *irq;
 
+	af_desc = kvzalloc(sizeof(*af_desc), GFP_KERNEL);
+	if (!af_desc)
+		return -ENOMEM;
+
 	/* In case SF irq pool does not exist, fallback to the PF irqs*/
-	if (!mlx5_irq_pool_is_sf_pool(pool))
+	if (!mlx5_irq_pool_is_sf_pool(pool)) {
+		kvfree(af_desc);
 		return comp_irq_request_pci(dev, vecidx);
+	}
 
-	af_desc.is_managed = false;
-	cpumask_copy(&af_desc.mask, cpu_online_mask);
-	cpumask_andnot(&af_desc.mask, &af_desc.mask, &table->used_cpus);
-	irq = mlx5_irq_affinity_request(dev, pool, &af_desc);
-	if (IS_ERR(irq))
+	af_desc->is_managed = false;
+	cpumask_copy(&af_desc->mask, cpu_online_mask);
+	cpumask_andnot(&af_desc->mask, &af_desc->mask, &table->used_cpus);
+	irq = mlx5_irq_affinity_request(dev, pool, af_desc);
+	if (IS_ERR(irq)) {
+		kvfree(af_desc);
 		return PTR_ERR(irq);
+	}
+
+	kvfree(af_desc);
 
 	cpumask_or(&table->used_cpus, &table->used_cpus, mlx5_irq_get_affinity_mask(irq));
 	mlx5_core_dbg(pool->dev, "IRQ %u mapped to cpu %*pbl, %u EQs on this irq\n",
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
index 2691d88cdee1..82d3c2568244 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
@@ -47,29 +47,40 @@ static int cpu_get_least_loaded(struct mlx5_irq_pool *pool,
 static struct mlx5_irq *
 irq_pool_request_irq(struct mlx5_irq_pool *pool, struct irq_affinity_desc *af_desc)
 {
-	struct irq_affinity_desc auto_desc = {};
+	struct irq_affinity_desc *auto_desc;
 	struct mlx5_irq *irq;
 	u32 irq_index;
 	int err;
 
+	auto_desc = kvzalloc(sizeof(*auto_desc), GFP_KERNEL);
+	if (!auto_desc)
+		return ERR_PTR(-ENOMEM);
+
 	err = xa_alloc(&pool->irqs, &irq_index, NULL, pool->xa_num_irqs, GFP_KERNEL);
-	if (err)
+	if (err) {
+		kvfree(auto_desc);
 		return ERR_PTR(err);
+	}
+
 	if (pool->irqs_per_cpu) {
 		if (cpumask_weight(&af_desc->mask) > 1)
 			/* if req_mask contain more then one CPU, set the least loadad CPU
 			 * of req_mask
 			 */
 			cpumask_set_cpu(cpu_get_least_loaded(pool, &af_desc->mask),
-					&auto_desc.mask);
+					&auto_desc->mask);
 		else
 			cpu_get(pool, cpumask_first(&af_desc->mask));
 	}
+
 	irq = mlx5_irq_alloc(pool, irq_index,
-			     cpumask_empty(&auto_desc.mask) ? af_desc : &auto_desc,
+			     cpumask_empty(&auto_desc->mask) ? af_desc : auto_desc,
 			     NULL);
 	if (IS_ERR(irq))
 		xa_erase(&pool->irqs, irq_index);
+
+	kvfree(auto_desc);
+
 	return irq;
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
index 40024cfa3099..48aad94b0a5d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
@@ -470,26 +470,32 @@ void mlx5_ctrl_irq_release(struct mlx5_core_dev *dev, struct mlx5_irq *ctrl_irq)
 struct mlx5_irq *mlx5_ctrl_irq_request(struct mlx5_core_dev *dev)
 {
 	struct mlx5_irq_pool *pool = ctrl_irq_pool_get(dev);
-	struct irq_affinity_desc af_desc;
+	struct irq_affinity_desc *af_desc;
 	struct mlx5_irq *irq;
 
-	cpumask_copy(&af_desc.mask, cpu_online_mask);
-	af_desc.is_managed = false;
+	af_desc = kvzalloc(sizeof(*af_desc), GFP_KERNEL);
+	if (!af_desc)
+		return ERR_PTR(-ENOMEM);
+
+	cpumask_copy(&af_desc->mask, cpu_online_mask);
+	af_desc->is_managed = false;
 	if (!mlx5_irq_pool_is_sf_pool(pool)) {
 		/* In case we are allocating a control IRQ from a pci device's pool.
 		 * This can happen also for a SF if the SFs pool is empty.
 		 */
 		if (!pool->xa_num_irqs.max) {
-			cpumask_clear(&af_desc.mask);
+			cpumask_clear(&af_desc->mask);
 			/* In case we only have a single IRQ for PF/VF */
-			cpumask_set_cpu(cpumask_first(cpu_online_mask), &af_desc.mask);
+			cpumask_set_cpu(cpumask_first(cpu_online_mask), &af_desc->mask);
 		}
 		/* Allocate the IRQ in index 0. The vector was already allocated */
-		irq = irq_pool_request_vector(pool, 0, &af_desc, NULL);
+		irq = irq_pool_request_vector(pool, 0, af_desc, NULL);
 	} else {
-		irq = mlx5_irq_affinity_request(dev, pool, &af_desc);
+		irq = mlx5_irq_affinity_request(dev, pool, af_desc);
 	}
 
+	kvfree(af_desc);
+
 	return irq;
 }
 
@@ -548,16 +554,26 @@ struct mlx5_irq *mlx5_irq_request_vector(struct mlx5_core_dev *dev, u16 cpu,
 {
 	struct mlx5_irq_table *table = mlx5_irq_table_get(dev);
 	struct mlx5_irq_pool *pool = table->pcif_pool;
-	struct irq_affinity_desc af_desc;
+	struct irq_affinity_desc *af_desc;
 	int offset = MLX5_IRQ_VEC_COMP_BASE;
+	struct mlx5_irq *irq;
+
+	af_desc = kvzalloc(sizeof(*af_desc), GFP_KERNEL);
+	if (!af_desc)
+		return ERR_PTR(-ENOMEM);
 
 	if (!pool->xa_num_irqs.max)
 		offset = 0;
 
-	af_desc.is_managed = false;
-	cpumask_clear(&af_desc.mask);
-	cpumask_set_cpu(cpu, &af_desc.mask);
-	return mlx5_irq_request(dev, vecidx + offset, &af_desc, rmap);
+	af_desc->is_managed = false;
+	cpumask_clear(&af_desc->mask);
+	cpumask_set_cpu(cpu, &af_desc->mask);
+
+	irq = mlx5_irq_request(dev, vecidx + offset, af_desc, rmap);
+
+	kvfree(af_desc);
+
+	return irq;
 }
 
 static struct mlx5_irq_pool *
-- 
2.49.0