net: ena: use constant value for net_device allocation

The patch changes the maximum number of RX/TX queues it advertises to
the kernel (via alloc_etherdev_mq()) from a value received from the
device to a constant value which is the minimum between 128 and the
number of CPUs in the system.

By allocating the net_device struct with a constant number of queues,
the driver is able to allocate it at a much earlier stage, before
calling any ena_com functions. This would allow to make all log prints
in ena_com to use netdev_* log functions instead or current pr_* ones.

Note:
netdev_* prints in ena_com functions that are called before
net_device registration in ena_probe() might print messages that are
a bit ugly (with strings like "(unnamed net_device) (uninitialized)").
However we decided to use netdev_* prints in these functions anyway,
for the sake of getting better messages later, when ena_com functions
are called after ena_probe() form other parts of the driver.
See discussion about this decision in [1].

[1] http://www.mail-archive.com/netdev@vger.kernel.org/msg353590.htmlSigned-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -29,6 +29,8 @@ MODULE_LICENSE("GPL");
 /* Time in jiffies before concluding the transmitter is hung. */
 #define TX_TIMEOUT  (5 * HZ)
 
+#define ENA_MAX_RINGS min_t(unsigned int, ENA_MAX_NUM_IO_QUEUES, num_possible_cpus())
+
 #define ENA_NAPI_BUDGET 64
 
 #define DEFAULT_MSG_ENABLE (NETIF_MSG_DRV | NETIF_MSG_PROBE | NETIF_MSG_IFUP | \
@@ -4176,18 +4178,34 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	ena_dev->dmadev = &pdev->dev;
 
+	netdev = alloc_etherdev_mq(sizeof(struct ena_adapter), ENA_MAX_RINGS);
+	if (!netdev) {
+		dev_err(&pdev->dev, "alloc_etherdev_mq failed\n");
+		rc = -ENOMEM;
+		goto err_free_region;
+	}
+
+	SET_NETDEV_DEV(netdev, &pdev->dev);
+	adapter = netdev_priv(netdev);
+	adapter->ena_dev = ena_dev;
+	adapter->netdev = netdev;
+	adapter->pdev = pdev;
+	adapter->msg_enable = netif_msg_init(debug, DEFAULT_MSG_ENABLE);
+
+	pci_set_drvdata(pdev, adapter);
+
 	rc = ena_device_init(ena_dev, pdev, &get_feat_ctx, &wd_state);
 	if (rc) {
 		dev_err(&pdev->dev, "ENA device init failed\n");
 		if (rc == -ETIME)
 			rc = -EPROBE_DEFER;
-		goto err_free_region;
+		goto err_netdev_destroy;
 	}
 
 	rc = ena_map_llq_mem_bar(pdev, ena_dev, bars);
 	if (rc) {
 		dev_err(&pdev->dev, "ENA llq bar mapping failed\n");
-		goto err_free_ena_dev;
+		goto err_device_destroy;
 	}
 
 	calc_queue_ctx.ena_dev = ena_dev;
@@ -4207,26 +4225,8 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto err_device_destroy;
 	}
 
-	/* dev zeroed in init_etherdev */
-	netdev = alloc_etherdev_mq(sizeof(struct ena_adapter), max_num_io_queues);
-	if (!netdev) {
-		dev_err(&pdev->dev, "alloc_etherdev_mq failed\n");
-		rc = -ENOMEM;
-		goto err_device_destroy;
-	}
-
-	SET_NETDEV_DEV(netdev, &pdev->dev);
-
-	adapter = netdev_priv(netdev);
-	pci_set_drvdata(pdev, adapter);
-
-	adapter->ena_dev = ena_dev;
-	adapter->netdev = netdev;
-	adapter->pdev = pdev;
-
 	ena_set_conf_feat_params(adapter, &get_feat_ctx);
 
-	adapter->msg_enable = netif_msg_init(debug, DEFAULT_MSG_ENABLE);
 	adapter->reset_reason = ENA_REGS_RESET_NORMAL;
 
 	adapter->requested_tx_ring_size = calc_queue_ctx.tx_queue_size;
@@ -4257,7 +4257,7 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (rc) {
 		dev_err(&pdev->dev,
 			"Failed to query interrupt moderation feature\n");
-		goto err_netdev_destroy;
+		goto err_device_destroy;
 	}
 	ena_init_io_rings(adapter,
 			  0,
@@ -4335,11 +4335,11 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	ena_disable_msix(adapter);
 err_worker_destroy:
 	del_timer(&adapter->timer_service);
-err_netdev_destroy:
-	free_netdev(netdev);
 err_device_destroy:
 	ena_com_delete_host_info(ena_dev);
 	ena_com_admin_destroy(ena_dev);
+err_netdev_destroy:
+	free_netdev(netdev);
 err_free_region:
 	ena_release_bars(ena_dev, pdev);
 err_free_ena_dev: