idpf: avoid bloating &idpf_q_vector with big %NR_CPUS

With CONFIG_MAXSMP, sizeof(cpumask_t) is 1 Kb. The queue vector
structure has them embedded, which means 1 additional Kb of not
really hotpath data.
We have cpumask_var_t, which is either an embedded cpumask or a pointer
for allocating it dynamically when it's big. Use it instead of plain
cpumasks and put &idpf_q_vector on a good diet.
Also remove redundant pointer to the interrupt name from the structure.
request_irq() saves it and free_irq() returns it on deinit, so that you
can free the memory.
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/idpf/idpf_lib.c

@@ -69,7 +69,7 @@ static void idpf_deinit_vector_stack(struct idpf_adapter *adapter)
 static void idpf_mb_intr_rel_irq(struct idpf_adapter *adapter)
 {
 	clear_bit(IDPF_MB_INTR_MODE, adapter->flags);
-	free_irq(adapter->msix_entries[0].vector, adapter);
+	kfree(free_irq(adapter->msix_entries[0].vector, adapter));
 	queue_delayed_work(adapter->mbx_wq, &adapter->mbx_task, 0);
 }
 
@@ -124,15 +124,14 @@ static void idpf_mb_irq_enable(struct idpf_adapter *adapter)
  */
 static int idpf_mb_intr_req_irq(struct idpf_adapter *adapter)
 {
-	struct idpf_q_vector *mb_vector = &adapter->mb_vector;
 	int irq_num, mb_vidx = 0, err;
+	char *name;
 
 	irq_num = adapter->msix_entries[mb_vidx].vector;
-	mb_vector->name = kasprintf(GFP_KERNEL, "%s-%s-%d",
+	name = kasprintf(GFP_KERNEL, "%s-%s-%d",
 			 dev_driver_string(&adapter->pdev->dev),
 			 "Mailbox", mb_vidx);
-	err = request_irq(irq_num, adapter->irq_mb_handler, 0,
-			  mb_vector->name, adapter);
+	err = request_irq(irq_num, adapter->irq_mb_handler, 0, name, adapter);
 	if (err) {
 		dev_err(&adapter->pdev->dev,
 			"IRQ request for mailbox failed, error: %d\n", err);

drivers/net/ethernet/intel/idpf/idpf_txrx.c

@@ -3613,6 +3613,8 @@ void idpf_vport_intr_rel(struct idpf_vport *vport)
 		q_vector->tx = NULL;
 		kfree(q_vector->rx);
 		q_vector->rx = NULL;
+
+		free_cpumask_var(q_vector->affinity_mask);
 	}
 
 	/* Clean up the mapping of queues to vectors */
@@ -3661,7 +3663,7 @@ static void idpf_vport_intr_rel_irq(struct idpf_vport *vport)
 
 		/* clear the affinity_mask in the IRQ descriptor */
 		irq_set_affinity_hint(irq_num, NULL);
-		free_irq(irq_num, q_vector);
+		kfree(free_irq(irq_num, q_vector));
 	}
 }
 
@@ -3812,6 +3814,7 @@ static int idpf_vport_intr_req_irq(struct idpf_vport *vport, char *basename)
 
 	for (vector = 0; vector < vport->num_q_vectors; vector++) {
 		struct idpf_q_vector *q_vector = &vport->q_vectors[vector];
+		char *name;
 
 		vidx = vport->q_vector_idxs[vector];
 		irq_num = adapter->msix_entries[vidx].vector;
@@ -3825,18 +3828,18 @@ static int idpf_vport_intr_req_irq(struct idpf_vport *vport, char *basename)
 		else
 			continue;
 
-		q_vector->name = kasprintf(GFP_KERNEL, "%s-%s-%d",
-					   basename, vec_name, vidx);
+		name = kasprintf(GFP_KERNEL, "%s-%s-%d", basename, vec_name,
+				 vidx);
 
 		err = request_irq(irq_num, idpf_vport_intr_clean_queues, 0,
-				  q_vector->name, q_vector);
+				  name, q_vector);
 		if (err) {
 			netdev_err(vport->netdev,
 				   "Request_irq failed, error: %d\n", err);
 			goto free_q_irqs;
 		}
 		/* assign the mask for this irq */
-		irq_set_affinity_hint(irq_num, &q_vector->affinity_mask);
+		irq_set_affinity_hint(irq_num, q_vector->affinity_mask);
 	}
 
 	return 0;
@@ -3845,7 +3848,7 @@ static int idpf_vport_intr_req_irq(struct idpf_vport *vport, char *basename)
 	while (--vector >= 0) {
 		vidx = vport->q_vector_idxs[vector];
 		irq_num = adapter->msix_entries[vidx].vector;
-		free_irq(irq_num, &vport->q_vectors[vector]);
+		kfree(free_irq(irq_num, &vport->q_vectors[vector]));
 	}
 
 	return err;
@@ -4255,7 +4258,7 @@ static void idpf_vport_intr_napi_add_all(struct idpf_vport *vport)
 
 		/* only set affinity_mask if the CPU is online */
 		if (cpu_online(v_idx))
-			cpumask_set_cpu(v_idx, &q_vector->affinity_mask);
+			cpumask_set_cpu(v_idx, q_vector->affinity_mask);
 	}
 }
 
@@ -4299,6 +4302,9 @@ int idpf_vport_intr_alloc(struct idpf_vport *vport)
 		q_vector->rx_intr_mode = IDPF_ITR_DYNAMIC;
 		q_vector->rx_itr_idx = VIRTCHNL2_ITR_IDX_0;
 
+		if (!zalloc_cpumask_var(&q_vector->affinity_mask, GFP_KERNEL))
+			goto error;
+
 		q_vector->tx = kcalloc(txqs_per_vector, sizeof(*q_vector->tx),
 				       GFP_KERNEL);
 		if (!q_vector->tx)

drivers/net/ethernet/intel/idpf/idpf_txrx.h

@@ -505,7 +505,6 @@ struct idpf_intr_reg {
 /**
  * struct idpf_q_vector
  * @vport: Vport back pointer
- * @affinity_mask: CPU affinity mask
  * @napi: napi handler
  * @v_idx: Vector index
  * @intr_reg: See struct idpf_intr_reg
@@ -526,11 +525,10 @@ struct idpf_intr_reg {
  * @num_bufq: Number of buffer queues
  * @bufq: Array of buffer queues to service
  * @total_events: Number of interrupts processed
- * @name: Queue vector name
+ * @affinity_mask: CPU affinity mask
  */
 struct idpf_q_vector {
 	struct idpf_vport *vport;
-	cpumask_t affinity_mask;
 	struct napi_struct napi;
 	u16 v_idx;
 	struct idpf_intr_reg intr_reg;
@@ -556,7 +554,8 @@ struct idpf_q_vector {
 	struct idpf_buf_queue **bufq;
 
 	u16 total_events;
-	char *name;
+
+	cpumask_var_t affinity_mask;
 };
 
 struct idpf_rx_queue_stats {